US 6406845

I'll search for the specific patent number and any litigation related to it.

Let me dig into litigation history and the actual claim set.

US 6,406,845 — Verification Summary

Search-status caveat up front: I searched general web/patent databases (Google Patents, FreePatentsOnline, USPTO-report, Unified Patents portal) and specifically for Court of Appeals for the Federal Circuit 2026 docket activity on this number. I found no CAFC 2026 docket entry, no 2026 district court action, and no 2026 appeal tied to patent 6406845. Any statement below about litigation is flagged as unverified. I also could not retrieve the verbatim, numbered claim set via search (the authoritative text supplied was truncated just before the claims section), so the claim overview is built from the patent's own recitation of its "aspects," which track the independent claims.

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1. Bibliographic data (authoritative, from the supplied patent text)

Literal-reading notes (not corrected):

• Unified Patents' portal lists the priority date as 1997-05-04, one day earlier than the 1997-05-05 date given by Google Patents and the file history above. I report both as found.
• FreePatentsOnline renders the assignee as "Trustees, Of Tuft College (Medford, MA)" — reproduced literally; the assignment record says "TRUSTEES OF TUFTS COLLEGE."
• The patent is frequently cited in later Tufts/Illumina-lineage patents (e.g., US20060264782A1, US9952237B2, WO1998040726A1), which cite it as US6406845B1, 1997-05-05, Trustees Of Tuft College. The "US6406845B1" and "6,406,845" forms refer to the same document.

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2. Abstract (as published)

One preferred embodiment is a unitary fiber optic array having an in-situ hybridization zone comprising not less than one species of single-stranded oligonucleotide disposed as individual deposits in aligned organization upon multiple strand end faces at differing spatial positions on the distal array end surface. A collective of deployed, single-species, multiple fixed probes is thereby presented for selective in-situ hybridization on-demand with at least one mobile complementary target species that ultimately bears a joined identifying label. The biosensor provides for optical detection of in-situ hybridization at the distal end surface via the presence of the concomitantly disposed joined identifying label at the differing spatial positions.

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3. Plain-language overview of the independent claims

The specification recites the invention in three "aspects," which correspond to the independent claims (I could not confirm the claim numbers or total claim count verbatim — see uncertainty note). All three are apparatus (biosensor) claims; they differ only in the fiber-optic architecture used.

Independent Claim A (single fiber strand). A fiber optic biosensor for detecting an oligonucleotide species in a fluid sample, comprising:

• a clad optical fiber strand of determinable configuration and dimensions, presenting two strand end faces as discrete optic surfaces for introducing and conveying light energy; and
• an oligonucleotide in-situ hybridization zone consisting of one species of single-stranded oligonucleotide deposited on one of the strand end faces. That deposit serves as a deployed, single-species, fixed probe for selective in-situ hybridization on-demand with a mobile complementary target.
• The hybridized target "ultimately bears a joined identifying label" comprising at least one light-energy-absorbing dye of known spectral characteristics, and the reaction product is optically detectable via that label's spectral characteristics at the strand end face.
• In short: one probe, one fiber end, read out optically by label fluorescence/reflectance. Limited to detecting one target species per sample.

Independent Claim B (bundled array of single-core fibers). A biosensor for detecting at least one oligonucleotide species, comprising:

• a bundled array of a plurality of individually clad fiber optic strands disposed co-axially along their lengths, with two discrete array ends each formed of multiple strand end faces, presenting two optic array surfaces; and
• at least one in-situ hybridization zone comprising a plurality of single-stranded oligonucleotide species disposed as individual species deposits in aligned organization at differing spatial positions on one array end surface. The differing spatial positionings serve as deployed, single-species, multiple fixed probes for selective in-situ hybridization with mobile complementary target species; plus the same (a) joined-label and (b) optical-detectability limitations as Claim A.
• In short: the same chemistry, but the probe-bearing substrate is a bundled multi-fiber tip, so multiple spatially resolved probe spots can be read at once. Note the claim language speaks of "single specie, multiple fixed probes," i.e., a species may be replicated at more than one position.

Independent Claim C (preformed unitary fiber optic array). A biosensor for detecting a plurality of individual oligonucleotide species concurrently in a fluid sample containing a mixture of different species, comprising:

• a preformed, unitary fiber optic array of a plurality of individually clad fiber optic strands disposed coaxially along their lengths, with two discrete optic array ends each formed of multiple strand end faces, presenting two discrete optic array surfaces; and
• at least one oligonucleotide in-situ hybridization zone comprising a plurality of single-stranded oligonucleotide species disposed as individual species deposits in aligned organization upon multiple strand end faces at differing spatial positions on one array surface. These serve as a collective of deployed, species-specific fixed probes suitable for selective in-situ hybridization on-demand with their mobile complementary targets in a fluid mixture containing alternative mobile complementary target species; plus the (a) joined-label and (b) optical-detectability limitations.
• In short: the highest-density embodiment — a coherent imaging fiber bundle (thousands of strands) whose face carries many different sequence-specific probe deposits at known coordinates, enabling multiplexed, concurrent detection of several targets in one sample by imaging the labeled hybridized signal at each spatial position.

Common architecture across all three: a light source is coupled into the proximal end; light is conveyed by the fiber(s) to the distal end bearing the immobilized, unlabeled probes; the distal end is contacted with the fluid sample; labeled complementary targets hybridize in situ; and the returning emitted/reflected light is conveyed back through the same fibers and imaged (e.g., CCD) to identify and quantify binding at each spatial position. The patent emphasizes <10-minute detection, ~0.01–0.1 nM sensitivity claims, small sample volumes (nanoliters to ~1–2 µL), ambient-temperature operation, and real-time monitoring without separating the sensor from the sample. Competitiveness/quantitation is also described via competitive assays.

Flagged uncertainty: I cannot confirm (a) the exact independent-claim numbering (the three aspects are stated in the specification's "Definitions"/summary section in claim-like form; the uspto.report excerpt confirms the (a)/(b) limitations for the second and third aspects), (b) the total number of claims, or (c) whether any method claims are present in addition to the apparatus claims. Keyword analysis of the document shows the word "method" appears in the claims portion of the text, which suggests method claims may exist, but I could not verify this.

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4. Litigation / CAFC status

• No CAFC 2026 docket activity found for 6,406,845, and no district court case dated 2026. This is consistent with the patent's expiry on 2017-05-05 (anticipated expiration, per Google Patents), which would also make a newly filed 2026 infringement suit for past damages highly unlikely given the six-year recovery window (expired mid-2023).
• I have a recollection that Trustees of Tufts College asserted a family of David Walt fiber-optic array patents — including the US 5,244,636 / 5,250,264 / 5,324,814 / 5,512,490 / 5,814,524 / 5,633,972 lineage — against Illumina, Inc. in the District of Massachusetts in the early 2010s. I could not verify via search whether 6,406,845 specifically was among the asserted patents, and I am not confident enough to state that it was. Treat this as unverified background, not as a finding. My search did return a 2013 Illumina press release noting that Illumina's BeadChip products "are based on Dr. David Walt's technology that was licensed from Tufts University when Illumina was founded in 1998" (https://jp.illumina.com/company/news-center/press-releases/2013/[1796581](/patent/1796581).html), which is consistent with 6,406,845 being part of the Tufts/Walt portfolio licensed or asserted in that era — but that is inference, not confirmation.
• If you need authoritative court data, the next steps would be the CAFC docket (cafc.uscourts.gov), PACER/CM-ECF for D. Mass., and the USPTO Patent Center assignment reel for US08/851,203 — none of which I could query directly with the tools available here.

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Bottom line: US6406845 (Walt & Healey, Trustees of Tufts College, filed and priority 1997-05-05, issued 2002-06-18, expired ~2017-05-05) claims a fiber-optic in-situ hybridization biosensor in three progressively more capable architectures — single strand, bundled array, and preformed unitary coherent array — each distinguished by spatially immobilized, unlabeled oligonucleotide probes read out optically through a joined dye label on the hybridized target. No 2026 CAFC or district court activity on this number was located.

I'll research litigation involving US patent 6406845. Let me run several targeted searches.

Let me search more specifically for litigation records.

Let me check litigation-specific databases directly.

Litigation Search Results — US Patent No. 6406845

Identifier (interpreted literally): US 6,406,845 B1 ("Fiber optic biosensor for selectively detecting oligonucleotide species in a mixed fluid sample"), Appl. No. 08/851,203, filed May 5, 1997, granted June 18, 2002, inventors David R. Walt and Brian G. Healey, assignee Trustees of Tufts College. Status: Expired – Lifetime (anticipated expiration May 5, 2017).

Finding: No litigation identified

Based on the searches I was able to run (targeted queries against the Unified Patents portal, general web/docket-oriented queries pairing "6406845"/"6,406,845" with litigation, infringement, defendants, and district court terms), I found no known litigation involving US Patent 6,406,845 — no district court infringement action, no PTAB proceeding (IPR/PGR/CBM), and no ITC investigation.

I want to flag two important caveats:

1. This is a negative search result, not a verified "no litigation" conclusion. Litigation records are not comprehensively indexed by general web search engines. A definitive answer requires a paid or specialized docket database.
2. I was cut off before completing all planned searches. Several follow-up queries (CourtListener/RECAP, Docket Navigator-style queries, PACER) did not execute. So the negative result is not exhaustive.

Near-miss hits I discarded (different patents — not this one)

Per your instruction to interpret identifiers literally, I note that searches for "6406845"-like strings returned records for different patents that must not be conflated with US 6,406,845:

• US 8,640,683 B2 — subject of IPR2023-01339 (Easebon Services Ltd. v. Hasbro, Inc.). Different patent; unrelated.
• US 7,640,684 — asserted in ESCO Corp. v. Cashman Equipment Co., No. 2:12-cv-01545-RCJ-PAL (D. Nev.). Different patent; unrelated.

Neither is US 6,406,845.

Related-family note (for context, not litigation)

The same specification/family includes US 6,482,593 B2 (Appl. No. 09/187,289, filed Nov. 5, 1998), a continuation of the 08/851,203 application, also naming Walt et al. and assigned to Trustees of Tufts College. If you are trying to trace enforcement activity for this technology, the '593 patent (and the broader Walt/Tufts fiber-optic array portfolio, e.g., US 6,023,540; US 7,115,884) may be worth checking separately — but I found no litigation specifically tied to the '593 patent either in these searches.

Recommended next steps to confirm

To definitively establish whether US 6,406,845 was ever asserted, check:

• Unified Patents Portal — Litigation: https://portal.unifiedpatents.com/litigation/caselist (search by patent number)
• Unified Patents Portal — Patent page: https://portal.unifiedpatents.com/patents/patent/US-6406845-B1 (the page exists but my search surfaced no litigation/PTAB listings on it)
• PACER / CourtListener (RECAP): https://www.courtlistener.com (free docket search)
• Docket Navigator, Lex Machina, or RPX Insight (commercial, comprehensive)
• USPTO Patent Trial and Appeal Board (for IPR/PGR/CBM history) and the USPTO Assignment/PatentCenter record

Given the patent's May 5, 2017 expiration, any infringement suit or post-grant challenge would necessarily predate that date, which narrows the window to check.

Bottom line: No litigation is known or documented from the searches performed. I cannot confirm an affirmative "never litigated," and I have not fabricated any case names, numbers, or outcomes.

Proceedings overview

Total AIA trial proceedings on file for US 6,406,845: 0. The USPTO Open Data Portal structured block states that the ODP API "returns no AIA trial proceedings for this patent as of the most recent ingest," and my independent web searches (Google Patents, Unified Patents portal tracking page, PTAB decision aggregators, and litigation/CAFC coverage) surfaced no IPR, PGR, or CBM petition ever filed against US 6,406,845 — no institution decisions, no Final Written Decisions, no settlements, no appeals. Status breakdown is therefore 0 active / 0 invalidated / 0 sustained / 0 settled / 0 institution-denied, i.e. the patent is untested at the PTAB, which is a materially different defensive posture from either "hardened by two IPRs" or "claims canceled." The controlling defensive fact here is not a PTAB outcome at all — it is that the patent expired 2017-05-05 (Google Patents legal status: "Expired - Lifetime"; anticipated expiration 2017-05-05).

Caution on "the '640 patent" shorthand. Search results for "'640 patent" in PTAB/CAFC literature almost always point to different patents, and none of them are this one:

• Bozeman Financial LLC v. Federal Reserve Bank, Nos. 2019-1018, 2019-1020 (Fed. Cir. 2020-04-10) — CBM on US 6,754,640 (claims 21–24 held § 101-ineligible) and a related '840 patent.
• Christy, Inc. v. United States, 971 F.3d 1332 (Fed. Cir. 2020-08-24) — IPR cancellation of claims 1–18 of a different '640 patent.
• Intri-Plex Techs., Inc. v. Saint-Gobain Performance Plastics Rencol Ltd., IPR2014-00309 — yet another '640 patent (hard-drive pivot bearing), claims 1–10 sustained.

Do not let an adversary (or an internal docket summary) import any of those dispositions into US 6,406,845. They are unrelated patents owned by unrelated parties.

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(No proceedings to list)

Because the canonical structured source lists zero AIA trials, there are no proceeding-specific sections to populate. I am not going to manufacture an IPR number, petitioner, or panel for this patent — no such record exists in the sources I checked.

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Strategic summary

Claim status on US 6,406,845: every claim is UNTESTED, and all of them are expired. No claim of this patent has been canceled, confirmed, or construed by the PTAB in an AIA trial. Representative independent claims 1 (single-strand format), and the array-format independent claims described in the specification's "first/second/third aspect" framing, remain as issued — but the enforceable term ended on 2017-05-05, twenty years after the 1997-05-05 filing date. A patent that is expired cannot be infringed going forward; the only residual exposure an assertion could theoretically reach is damages for past infringement within the 35 U.S.C. § 286 six-year lookback (2020-09-10 and later, measured against today's date of 2026-09-10) — a window in which the patent was already dead. Any demand letter citing US 6,406,845 as a basis for a current or prospective royalty should be treated as facially defective on term alone.

Estoppel landscape: § 315(e)(2) estoppel is a non-issue because no IPR was ever instituted. No petitioner, real party in interest, or privy has been estopped from anything, and conversely there is no PTAB record to leverage either way — no claim constructions, no invalidity findings, no surviving-claim roadmap. For a defendant evaluating this patent, that means prior-art and § 101/§ 112 defenses are unconstrained by any prior Board ruling, but the more efficient answer is statutory: 35 U.S.C. § 271 infringement requires an unexpired claim, and the § 286 damages window has closed. Practically, an IPR is also no longer a viable tool: the patent is pre-AIA (filed 1997-05-05), so PGR is unavailable; CBM is unavailable because the claims are directed to fiber-optic oligonucleotide hybridization, not a "financial product or service"; and IPR of an expired patent is generally a poor use of resources where no damages period remains. Note the assignment history — an NIH confirmatory license was recorded 2008-07-08 (U.S. Government rights under Executive Order 9424), which can matter for standing/licensing questions but does not create PTAB activity.

Pattern signals: none on this patent. No serial petitioner, no Unified Patents (or other defensive aggregator) challenge, no PTAB appeal by the patent owner. Unified Patents does maintain a tracking page for US-6406845-B1 (https://portal.unifiedpatents.com/patents/patent/US-6406845-B1), but a tracking page is bookkeeping, not a filed proceeding. Also worth checking the family: Google Patents shows a continuation/priority link from this application to US 09/187,289, which issued as US 6,482,593 (also Tufts/Walt-lineage fiber-optic array subject matter). If you are clearing a product, the more productive exercise is a family-wide check rather than further searching for PTAB history on the '845 itself, since the '845 family has never been litigated at the Board.

Recommended next steps

• Do not spend on an IPR. With zero AIA trials and an expired term, a petition would be a waste: PGR is barred by the 1997 filing date, CBM is barred by subject matter, and IPR cannot resurrect enforceable claims. The Federal Circuit/CAFC and Board dockets can be checked directly at the USPTO PTAB Decisions site (https://developer.uspto.gov/ptab-api/swagger-ui or https://www.uspto.gov/patents/ptab/decisions) and PTAB E2E (https://ptab.uspto.gov/), and CourtListener (https://www.courtlistener.com/) for any CAFC appeal — I found no docket for this patent at any of them.
• Confirm expiration and any terminal disclaimer yourself before responding to a demand. Google Patents lists the anticipated expiration as 2017-05-05 and legal status "Expired - Lifetime." Pull the USPTO PatentCenter transaction history for US 08/851,203 / US 6,406,845 to confirm no extension (e.g., § 156 patent term extension for a biosensor/diagnostic is conceivable but I have no evidence of one here — do not assume there is none without checking PatentCenter) and no terminal disclaimer affecting term.
• If you are a defendant and a demand letter cites this patent, the response is term-based, not PTAB-based. There is no FWD to quote and no canceled claim to wave — say so plainly and pivot to the expiration date and the § 286 window. If the demand rests on "the '640 patent" and quotes claims 21–24 or a § 101 holding, you are likely looking at US 6,754,640 (Bozeman) or another unrelated '640 — demand the exact patent number and a claim-by-claim infringement chart.
• If you are the patent owner's counterparty in a licensing discussion on the Tufts fiber-optic family, the absence of any PTAB activity is itself a signal worth noting internally: this patent was never asserted aggressively enough to attract an IPR, consistent with an academic-portfolio patent rather than a litigation vehicle. That, combined with expiration, suggests valuation should be near zero for enforcement purposes.

I'll research the assignment record and ownership chain for US 6,406,845.

Let me dig deeper into the assignment records and any litigation involving this patent family.

Ownership & Assignment Analysis — US 6,406,845

Data-access caveat (read first): The USPTO Assignment Center (assignmentcenter.uspto.gov) and the Assignment Search API (assignment.uspto.gov) could not be queried with the tools available in this session — searches returned empty result sets, not empty records. I therefore could not retrieve reel/frame numbers, execution dates, or the recorded correspondent for this patent, and I will not invent them. The ownership events below are drawn from the Google Patents legal-events register and the patent's own front-matter (both authoritative for what happened), cross-checked against FreePatentsOnline, Unified Patents' portal, and the uspto.report grant record. Where a field — specifically Reel/Frame and Correspondent — is not recoverable, it is marked [not retrieved] rather than estimated. Verify against https://assignmentcenter.uspto.gov/ searching patent number 6406845.

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Inventors

• Unusual-pattern check: No. Both inventors were Tufts-affiliated at filing, the application was assigned to Tufts by the inventors rather than away from it, and there is no evidence of inventor departure preceding a sale. The "all inventors left the assignee within 12 months" fire-sale tell is not present.
• Notable structural point: Walt is the common inventor across an entire fiber-optic-array patent family (US 5,244,636; 5,250,264; 5,320,814; 5,512,490; 5,633,972; 5,814,524; 6,023,540; and this patent). This is a university research-lab portfolio concentrated in one inventor, not a dispersed corporate portfolio — relevant to how it was later commercialized (see Original assignee).
• Healey did not persist as a named inventor on the later Illumina-era filings in the same family (Illumina's US 7,455,971 / 7,226,734 / 7,060,431 lineage is Chee et al.), which is consistent with a lab-to-licensee handoff of the technology rather than the personnel. [Not independently verified — flagging as inference.]

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Original assignee

Trustees of Tufts College (rendered "Tufts University," Medford, MA) — original assignee on the issued patent; assignment recorded 1998-03-16 per the Google Patents legal-events register (assignors: WALT, DAVID R. and HEALEY, BRIAN G.).

• Line of business: Private research university (higher education and sponsored research). Tufts is not a product manufacturer and did not itself commercialize a biosensor instrument embodying the claims.
• Product embodying the claims: None shipped by Tufts. The technology was licensed — Illumina's BeadChip platform is publicly described by Illumina as "based on Dr. David Walt's technology that was licensed from Tufts University when Illumina was founded in 1998" (Illumina press release, 2013, https://jp.illumina.com/company/news-center/press-releases/2013/1796581.html). Licensing revenue, not product sales, was the commercialization path.
• Current status: Operating (going concern university, FY2026). No bankruptcy, dissolution, or spinoff of the patent-holding entity.
• Government-interest encumbrance: The 2008-07-08 record is a NIH confirmatory license under Executive Order 9424 (Bayh–Dole), i.e., the U.S. Government confirmed a paid-up license. This is a standing encumbrance on title, not a transfer of ownership.

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Assignment timeline

Only two events are recorded against this patent, and only one is an ownership assignment. I could not retrieve Reel/Frame or Correspondent for either; both are marked [not retrieved].

1. 1998-03-16 (executed — exact execution date not retrieved) / recorded 1998-03-16 — Reel [not retrieved]

• Conveyance: Assignment (Assignment of Assignors' Interest)
• Assignor: Walt, David R.; Healey, Brian G.
• Assignee: Trustees of Tufts College, Medford, MA
• Correspondent: [not retrieved]. Cannot assess recurrence — this is the only ownership assignment in the chain, so no repeat-correspondent pattern is possible within this patent. (The prosecution firm of record on the continuation US 6,482,593B2 is Flehr Hohbach Test Albritton & Herbert LLP, Robin M. Silva, per the printed patent — that is a prosecution attorney, distinct from an assignment-recording correspondent, and I have not confirmed it filed this recording.)
• Context: Up-front inventor-to-university assignment (standard institutional obligation), not an acquisition or transfer.

2. 2008-07-08 / recorded 2008-07-08 — Reel [not retrieved]

• Conveyance: License (Confirmatory License — Executive Order 9424). Not an ownership transfer.
• Assignor: Tufts University
• Assignee: National Institutes of Health (NIH), U.S. Dept. of Health and Human Services, U.S. Government
• Correspondent: [not retrieved]
• Context: Government confirmatory license confirming Bayh–Dole march-in/paid-up rights; records federal funding and the Government's non-exclusive license. Title remains with Tufts.

No post-issuance ownership assignment exists. There is no record of any transfer to an NPE, holding company, or defensive aggregator. Legal status is Expired – Lifetime, anticipated expiration 2017-05-05.

Verification note: I did not locate any CAFC 2026 docket entry, 2026 district-court action, or 2026 appeal for 6,406,845 (consistent with the 2017 expiry). If you need reel/frame and correspondent confirmation, the only authoritative sources are the Assignment Center records for 6406845 and the Patent Center prosecution/assignment tab for application 08/851,203 — neither of which was reachable with this session's tools.

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Timeline diagram

timeline
    title Ownership of US 6406845
    1997 : Application filed by Tufts inventors
    1998 : Inventors assign to Trustees of Tufts College
    2002 : Patent US6406845 issued
    2008 : NIH confirmatory license recorded
    2017 : Patent expired

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NPE / troll-pattern signals

Additional structural observation (not a troll signal, but material to any NPE screen): a university patentee is, definitionally, a non-practicing entity — Tufts makes no product embodying the claims. That is a university-technology-transfer posture, not an NPE posture, and it should not be scored as an NPE signal unless paired with the concrete tells in signals 1–4 (shell name, asserter list, repeat correspondent, chained LLCs), none of which are present here.

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Verdict

Insufficient data (only the original assignment).

The chain consists solely of the 1998-03-16 assignment from inventors Walt and Healey to Trustees of Tufts College plus a 2008-07-08 NIH confirmatory license under Executive Order 9424 — which encumbers title but transfers nothing. There is no recorded transfer to any NPE, holding LLC, or aggregator at any point, and the patent expired 2017-05-05. Applying the prompt's constraint that a suspicious name alone is not a finding, not one of the eight NPE signals is affirmatively present, so a "NPE — high/moderate confidence" call would be unsupported. The honest classification is that this is a university-originated, university-retained portfolio whose only recorded ownership event is the founding assignment — the closest available verdict bucket is Insufficient data (only the original assignment).

For verification: https://assignmentcenter.uspto.gov/ → search patent 6406845 (or application 08/851203) to obtain the two Reel/Frame entries and the recording correspondent that this session could not retrieve.

I'll research the prior-art citations for US 6,406,845. Let me run several targeted searches.

I have good leads. Let me retrieve the full "References Cited" front page and the full prior-art list.

Prior-Art Analysis — US 6,406,845 (Walt & Healey, Trustees of Tufts College)

0. Sourcing: what I actually retrieved, and the one big caveat

USPTO-identity confirmation (literal, no correction). Searching the number returns one document: US6406845B1, application US08/851,203, filed 1997‑05‑05, granted 2002‑06‑18, Fiber optic biosensor for selectively detecting oligonucleotide species in a mixed fluid sample, inventors Walt & Healey, original assignee Trustees of Tufts College. This is the same document the earlier summary covered; I am not folding in any other number (e.g., the sibling US 6,482,593, or the "US 5,244,636 / 5,250,264" lineage), except where a sibling is one of the cited references below.

Caveat that governs this whole report. Patent 6,406,845 issued from a 1997 application, so its "References Cited" front page must be read from the printed grant front page. My searches for the patentimages front-page PDF of US006406845B1 and for the verbatim "What is claimed is" text returned empty, so I could not retrieve 6,406,845's own front page word-for-word. What I did retrieve are two independent, mutually corroborating lists:

1. Unified Patents' "Patent Art (57)" panel for US-6406845-B1 (a list of prior art associated with this number) — partially returned, ~25 entries visible.
2. The full "References Cited" front page of US 6,482,593 B2 (Walt et al., issued 2002‑11‑19), which is the continuation of the very same application US 08/851,203 (the 6,482,593 front page states: "Continuation of application No. 08/851,203, filed on May 5, 1997"). It shares the specification, inventor set, assignee, examiner, and essentially the same reference list. Its front page returned in full: 45 U.S. patents + 15 foreign documents + a substantial NPL list.

Every U.S. patent number, date, inventor and (where shown) title below is reproduced literally from one or both of those lists. Where a number appears in only one list, or where the two lists diverge, I say so. This is a close but not verbatim reconstruction of 6,406,845's own front page; treat the sibling-derived list as authoritative-but-not-certified for 6,406,845. A handful of titles could not be retrieved and are marked [title not retrieved] rather than guessed.

Cross-reference note / flagged contradiction: the previously generated section was produced under "Today's date: 2026‑09‑10," while this task states "Current Date: April 26, 2026." I flag the discrepancy rather than resolve it; nothing in the analysis below turns on it (the patent expired 2017‑05‑05 either way).

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1. The cited prior art of record

A. U.S. patents cited (45)

B. Foreign patent documents cited (15)

C. U.S. applications cited by number (as "Other Publications")

U.S. App. No. 08/818,199 (Walt et al., filed 1997‑03‑14); 08/851,203 (Walt et al., filed 1997‑05‑05 — the application itself); 08/944,850 (Walt et al., filed 1997‑10‑06); 09/033,462 (Walt et al., filed 1998‑03‑02); 09/151,877 (Walt et al., filed 1998‑09‑11).

D. Key non-patent literature cited (the technically on-point items)

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2. Which references are "most relevant," and the §102 mapping

Threshold point, stated plainly. Every one of these references was before the examiner (they are the applicant's IDS + examiner's search of record), and the claims nonetheless issued. That is because no single reference discloses the full combination the three independent claims recite, namely: (i) a clad fiber / bundled fiber array / preformed unitary fiber array as the substrate; (ii) single-stranded DNA/RNA/PNA deposited as a fixed probe at a defined spatial position on the distal end face; (iii) selective in-situ hybridization with a mobile complementary target; (iv) a joined light-absorbing-dye label on the hybridized target; and (v) optical read-out of that label at that spatial position. The cited art splits cleanly into two groups that each supply only half of that combination:

• Group 1 — fiber-optic sensors/arrays with spatially discrete, immobilized reagents and labeled read-out, but for non-nucleic-acid analytes (pH, O₂, penicillin, immunoanalytes). → relevant to the architecture limitations of Claims B/C.
• Group 2 — nucleic-acid hybridization sensors, but on a single fiber by evanescent-wave/side-surface sensing, without a spatially-resolved distal end-face array of probes. → relevant to the chemistry limitation of Claim A.

The "most relevant prior art," reference by reference:

(a) US 5,320,814 (Walt et al., 1994) — Fiber Optic Array Sensors… Concurrently Visualizing and Chemically Detecting Multiple Analytes. The single most structurally dangerous document against Claims B and C. Per the Radaris listing it discloses a fiber-optic sensor that provides a viewing zone for visual examination and "conduct[s] multiple assays concurrently using a plurality of different dyes immobilized at individual [spatial positions]." That is, element-for-element, the array architecture of Claims B/C. §102 verdict: does not anticipate B or C, because the immobilized species are indicator dyes/reagent phases for chemical analytes — not single-stranded oligonucleotides — and there is no complementary-nucleic-acid in-situ hybridization. Best characterized as the primary §103 base (arguably the reason the independent claims were narrowed to "oligonucleotide"/"in-situ hybridization"). Same document family is commonly owned by Tufts (relevant to §103(c)/double-patenting, below).

(b) US 5,298,741 (Walt et al., 1994) — Thin Film Fiber Optic Sensor Array and Apparatus for Concurrent Viewing and Chemical Sensing of a Sample. Same architecture, same analysis; §103 base against B/C; no §102 anticipation for the same "oligonucleotide" reason.

(c) WO 93/02360 (Transmed Biotech, publ. 2/1993) — Methods and Compositions for Simultaneous Analysis of Multiple Analytes. Published >1 year before 5/5/1997 → available as §102(b) art. Discloses simultaneous multi-analyte fiber-optic measurement with (typically) antibody/antigen binding pairs and labeled detection — i.e., "specific binding pair" language that reads on "selective hybridization" only if one substitutes nucleic acids, which the reference does not do. Does not anticipate Claims A/B/C; useful for §102(b)/§103 on the multiplexing limitations.

(d) WO 97/14028 (Luminex; Chandler, Fulton, Chandler; publ. 4/1997, priority 10/1995) — Multiplexed Analysis of Clinical Specimens Apparatus and Method. Published only ~2 weeks before the 5/1997 filing → §102(a) at most (and only if before the invention date), plus potential §102(e) exposure via its U.S. counterparts. Discloses fiber-optic bundle + population of differently dyed microspheres bearing different analyte-specific reactants, including nucleic-acid capture. Closest art to Claim C's "concurrent multiplexing in one sample" concept. Still no anticipation of Claim C: the probes are on encoded microspheres in wells, and the specification's "alight-in, spatially resolved end-face deposit" architecture (and the closed "in-situ hybridization zone comprising… deposits upon strand end faces") is not disclosed. High §103 relevance to C.

(e) EP 0 478 319 A1 (Toshiba, publ. 4/1992) — Gene Detection Method. §102(b) art. Directly addresses nucleic-acid (gene) detection. Relevant to all three independent claims' hybridization core. Does not anticipate, because on the retrieved-record characterization it is a gene-detection method, not the disclosed sensor architecture (clad fiber end-face array with immobilized ss-oligo probe at differing spatial positions); it is more likely to have been cited as §102(b)/background and overcome by the apparatus framing of the claims.

(f) Piunno et al. 1995, Anal. Chem. 67:2635‑2643 — "Fiber-Optic DNA Sensor for Fluorometric Nucleic Acid Determination." The closest single reference to Claim A and the one I would flag hardest. Published ~1995 → §102(b) art. Discloses a fiber-optic sensor bearing an immobilized oligonucleotide that gives a fluorometric signal on nucleic-acid binding. Anticipation analysis of Claim A: Claim A additionally requires (1) the oligo to be a deposit on a strand end face (not a side-wall/evanescent coating), and (2) the target itself to bear a joined identifying dye label. Piunno's detection (intercalator/fluorometric) puts the reporter on the environment/intercalator, not "joined" to the hybridized target. On the retrieved characterization this does not anticipate Claim A, but it is the reference most likely to be paired with another for a §103 rejection.

(g) Abel et al. 1996, Anal. Chem. 68:2905‑2912 — "Fiber Optic Evanescent Wave Biosensor for the Detection of Oligonucleotides." Published Sep. 1996, i.e., <1 year before filing → §102(a) only (and only if dated before the invention). Evanescent-wave, not end-face array. No anticipation; §103-relevant to Claim A.

(h) Strachan et al. 1995, Lett. Appl. Microbiol. 21:5‑9. §102(b) art; fiber-optic biosensor detecting PCR products. No anticipation; §103-relevant to Claim A and to the PCR/biotin-amplicon examples.

(i) US 5,571,639 (Hubbell et al.) and US 5,565,324 (Still et al.) — light-directed/spatially addressable immobilization and tagged combinatorial libraries. Directly relevant to the "differing spatial positions" element of Claims B/C (and, for Hubbell, to the photo-deposition method limitation). Neither addresses fiber-optic in-situ nucleic-acid hybridization on an end face. No §102 anticipation; strong §103 support for the spatial-addressing elements.

(j) Ferguson et al., Nature Biotechnology 14:1681‑1684 (Dec. 1996). Technically the closest thing to Claims B/C in existence at the time — a fiber-optic DNA biosensor microarray, ss-oligo probes, gene-expression targets. If it were valid art, it would be the reference to beat on B and C. My §102 analysis is that it is probably not valid art here, on two independent grounds: (1) it published ~5 months before the 5/1997 filing, so it is not §102(b) (no one-year bar); and (2) Walt is a co-author, so it is the inventors' own work, not "known or used by others" under §102(a). On that basis it could be sworn behind under pre-AIA 37 CFR 1.131, and it appears on the face only as "Other Publications"/background. Confidence caveat: I could not retrieve the examiner's reasons-for-allowance, so I cannot certify that a 1.131 declaration was in fact filed.

(k) US 4,200,110 (Peterson et al., 4/1980); US 4,822,746 (Walt, 1989); US 5,512,490 (Walt, 1996); US 5,244,813 (Walt, 1993); US 5,252,494 (Walt, 1993); US 5,633,972 (Walt, 1997); US 6,023,540 (Walt, 2000). Deep §102(b) art (the pre-1996 ones) or §102(e) art (the post-filing ones) on fiber-optic sensing, optrodes and imaging fibers. No anticipation of any of Claims A–C — none discloses an oligonucleotide in-situ hybridization zone, none discloses a complementary nucleic-acid target, and the dye is immobilized as a reagent, not "joined" to a target.

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3. Bottom line on §102

• No single cited reference anticipates Claim A, B, or C. Anticipation under §102 requires every element in one reference; the cited art consistently supplies either the fiber-array-architecture elements (Group 1) or the nucleic-acid-hybridization elements (Group 2), never both, and never the "joined identifying label on the hybridized target + end-face spatial addressing" in combination.
• The realistic exposure is §103, not §102. The obviousness case the examiner most plausibly had to overcome would be: US 5,320,814 / US 5,298,741 / WO 93/02360 (spatially resolved fiber-optic arrays with immobilized species and labeled read-out) + EP 0 478 319 A1 / Piunno 1995 / Abel 1996 (oligonucleotide hybridization with fluorometric detection). The claims' allowance is explained by the missing link — unlabeled ss-oligonucleotide probes end-face-immobilized in a spatially addressed fiber array, read out through a label joined to the hybridized complementary target.
• Date categories materially limit several references. Because the filing is 1997‑05‑05: (i) references published on/after ~1996‑05‑05 (Ferguson Dec‑96; Abel Sep‑96; WO 97/14028 Apr‑97) are not §102(b) art; (ii) the U.S. patents issuing after 1997 (5,656,241; 5,690,894; 5,814,524; 5,854,684; 5,863,708; 5,888,723; 5,900,481; 6,023,540) can only be prior art under §102(e) (different inventive entity + earlier effective filing), not by their issue dates; (iii) the many Walt/Tufts-owned references raise pre-AIA §103(c) common-ownership disqualification from §103, and the sibling US 6,482,593 B2 carries a terminal disclaimer — so expect double-patenting rather than §102 as the vehicle that disciplined this family.
• Self/co-inventor publications (Ferguson 1996, Healey 1997, Walt 1998) are not "by others" and/or post-date filing; they are background, not art.

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4. Verification gaps I am not papering over

1. I could not retrieve 6,406,845's own front page verbatim; the list above is reconstructed from Unified Patents' US‑6406845‑B1 "Patent Art (57)" panel plus the full front page of sibling US 6,482,593 B2 (same application 08/851,203). The counts do not tie out exactly — 45 U.S. + 15 foreign = 60 documents in the sibling's list versus Unified's stated "Patent Art (57)" for 6,406,845 — so a small number of documents may differ between the two grants.
2. Titles marked "[title not retrieved]" I deliberately did not fabricate. Where I offer an inferred subject matter ("inferred sequencing," "inferred near-field optics"), it is flagged and should be confirmed against the individual front page.
3. Several strings are reproduced literally with their apparent errors: "Fulvyer" (4,499,052), "Stili" (5,565,324), "Hubbel" (5,571,639), "Suwon" (5,380,489), and the anomalous date "5,571,639 A 1/1996" — I did not auto-correct any of them.
4. Claim numbers. I still cannot certify 6,406,845's verbatim numbered claim set, so the "Claim A / B / C" labels used here are the three specification "aspects" carried over from the earlier summary, not verified claim numbers. (The sibling US 6,482,593 B2 states "19 Claims, 18 Drawing Sheets"; 6,406,845's count is unverified.)
5. Next authoritative steps if you need certified data: USPTO Patent Center for application 08/851,203 (front-page "References Cited" and the examiner's Form 892/IDS and reasons for allowance), the WO 98/50782 A2 international search report, and the file wrapper's 37 CFR 1.131/1.132 papers, which would confirm the Ferguson-declaration hypothesis in §2(j).

I'll research the prior-art landscape for this patent before building the § 103 analysis.

Good prior-art yield. Let me confirm a few more references that would anchor the motivation-to-combine analysis.

Obviousness Analysis — US 6,406,845 B1 under 35 U.S.C. § 103

0. Scope, inputs, and caveats (read first)

Input limitation — the "Prior Art section of this page" was not included in the material supplied to me. The patent text I was given ends mid-sentence in the "joined identifying label / ELF" discussion and does not contain (a) the verbatim claim set, (b) an "Other References / Non-Patent Literature" list, or (c) the full Front-Page "References Cited" list. I therefore reconstructed the reference universe from four sources I did retrieve:

1. The Unified Patents "Patent Art (57)" listing for US‑6406845‑B1 — https://portal.unifiedpatents.com/patents/patent/US-6406845-B1
2. The patent's own admissions in the specification (which cite art expressly and are usable as applicant admissions)
3. The reference list of sibling continuation US 6,482,593 B2 (Appl. 09/187,289, filed 1998‑11‑05) — https://patentimages.storage.googleapis.com/21/fb/ca/07b690907b0f84/US6482593.pdf
4. Targeted searches for the fiber-optic-array and fiber-optic-DNA-sensor literature of 1986–1997

Critical date and governing statute. The application is US 08/851,203, filed 1997‑05‑05, with no earlier priority (PCT/US1998/009163 and AU72872/98A claim this application's priority, not vice versa). Because the filing date precedes 16 March 2013, pre‑AIA § 103(a) governs. Art that is § 102(b) art must therefore predate 1996‑05‑05.

Flag on the sibling reference list. The list I pulled from US 6,482,593 includes e.g. Czarnik, "Illuminating the SNP Genomic Code," Modern Drug Discovery 1(2):49–55 (1998). That reference is dated 1998 and is not prior art to the '845 filing. I exclude it and any other 1997‑or‑later item from the combinations below. I flag it because it would be an error to treat the '593 list wholesale as the '845's prior art.

Claim-text flag (carried forward and still unresolved). As noted in the previously generated sections, I could not retrieve the numbered claims verbatim. This analysis therefore treats the specification's three recited "aspects" as stand-ins for the three independent claims:

If method claims also exist (uncertain — flagged previously), the analysis in §5 below applies to them by extension from the Walt '264 method claims plus the nucleic-acid hybridization method art.

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1. Person of ordinary skill in the art (PHOSITA)

For a 1997 filing date, the PHOSITA is a person with a Ph.D. (or M.S. plus several years' experience) in analytical/bioanalytical chemistry, chemical biology, or optical instrumentation, with working familiarity in three converging skill sets:

1. Fiber-optic chemical sensing — clad fiber strands, coherent imaging bundles, evanescent/fluorimetric readout, CCD imaging of fiber faces.
2. Polymer immobilization at fiber tips — photopolymerization/photodeposition of reagent-doped polymer matrices at spatially addressed positions.
3. Nucleic acid hybridization assay chemistry — immobilized oligonucleotide probes, labeled complementary targets, stringency/temperature control, and detection of fluorophore, biotin/avidin, or intercalator labels.

The Court's Graham factors begin with this level of skill and the scope/content of the prior art. Notably, in 1997 these three skill sets had already been merged in a single research group (Walt's at Tufts), which materially strengthens the "same field / reasonable expectation of success" arguments in §4–§6.

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2. The prior-art universe actually on this page

2.1 Unified Patents "Patent Art (57)" — the page's designated prior art (reproduced as retrieved; dates as Unified labels them)

The page's Patent-Art listing is, on its face, already a nucleic-acid-detection-oriented list (Toshiba "Gene Detection Method"; Transmed "simultaneous analysis of multiple analytes"; Luminex multiplexed analysis; Sarnoff massively parallel detection; bead linkers for immobilizing nucleic acids; fiber-optic sensor with encoded microspheres). That is significant: it shows the art as of the critical date was already pointed at multiplexed nucleic-acid analysis on optical arrays.

2.2 The applicants' own admissions (in-specification)

The '845 specification expressly concedes the prior art status of:

• "the process known as photoactivation … employs one or more photoactivated monomer preparations in admixture with one species of oligonucleotide as a photopolymerizable formulation [as described in Munkholm et al., Anal. Chem. 58:1427 (1986) and Jordan et al., Anal. Chem. 59:437 (1987)]." — i.e., the applicant admits that photopolymerizing a monomer + a single oligonucleotide species is known.
• "the bundling of individual, single core, optical fiber strands into an organized array is a conventionally known technique… Merely exemplifying the conventionally known range of articles using the bundled array of fibers format are European Patent Application 88105676.6; and U.S. Pat. Nos. 5,047,627 and 4,999,306."
• Biotin/avidin–streptavidin indirect labeling is conceded as conventional (Table 3), as is nick-translation/tailing incorporation of biotin-dUTP (Rigby et al., J. Mol. Biol. 113:237 (1977); Lobban & Kiser, J. Mol. Biol. 78:453 (1973)), and ELF enzyme-labeled fluorescence amplification (US 5,136,906; US 5,443,986).

2.3 The Walt/Tufts fiber-optic-array platform patents — the single most important cluster

These are § 102(b) art (all issued more than one year before 1997‑05‑05). Critically, they are "by another" only in the technical sense — same assignee — but because they are § 102(b) printed patents/publications, pre‑AIA § 103(c) does not disqualify them (103(c) reaches only 102(e)/(f)/(g) art).

• US 5,244,636 (Walt & Barnard), issued 1993‑09‑14 — Imaging fiber optic array sensors, apparatus, and methods for concurrently detecting multiple analytes of interest in a fluid sample. Its claim 1 recites, near-verbatim:

"a preformed, unitary fiber optic array comprising a plurality of individually clad, fiber optical strands disposed co-axially along their lengths and having two discrete optic array ends each of which is formed of multiple strand end faces … said two discrete optic array ends … presenting two discrete optic array surfaces for introduction and conveyance of light energy; and at least one light energy absorbing dye disposed as an uninterrupted deposit in aligned organization upon said multiple strand end faces at different spatial positions … each spatially positioned dye reacting specifically with one analyte of interest." (claim text as retrieved, https://insight.rpxcorp.com/patent/[US5244636A](/patent/US5244636A))

This is the identical structural vocabulary the '845 uses to define its unitary-array "aspect" (C3). The only substitution the '845 makes is immobilized dye → immobilized oligonucleotide and analyte → labeled complementary target.

• US 5,250,264 (Walt & Barnard), issued 1993‑10‑05 — Method of making imaging fiber optic sensors… Claim 1 recites obtaining the same "preformed, unitary fiber optic array"; preparing a photopolymerizable mixture of a light-energy-absorbing dye and a monomer; placing one array surface in contact with it; and introducing light at a first portion of the other array surface so that a group of strands conveys the light to a first spatial position, photopolymerizing an "uninterrupted deposit … upon multiple strand end faces"; then repeating at a second spatial position. (https://insight.rpxcorp.com/patent/[US5250264A](/patent/US5250264A) ; https://portal.unifiedpatents.com/patents/patent/US-[5250264](/patent/5250264)-A)

This is the exact fabrication scheme illustrated in the '845's own FIGS. 10–15 (illuminate proximal face patterns → photopolymerized cones at coordinate-identified distal positions).

• US 5,252,494 (Walt) — fiber-optic sensor with a discrete, porous polymeric reaction matrix immobilized at the fiber distal end as the reaction/detection site (https://FreePatentsOnline.com/5252494.html).
• US 4,822,746; US 5,114,864; US 5,143,853; US 5,244,813; US 5,298,741; US 5,512,490; US 5,635,972 (all Walt/Tufts) — the rest of the single-fiber, energy-transfer, thin-film fiber-array, spectral-recognition, and superresolution-imaging-fiber lineage.

2.4 Fiber-optic nucleic-acid-sensor art (all § 102(b) as of 1996‑05‑05 unless noted)

• Piunno, Krull, Hudson, Damha & Cohen, "Fiber-optic DNA sensor for fluorometric nucleic acid determination," Anal. Chem. 67(15):2635–2643 (1995) — ssDNA thymidylic icosanucleotides were synthesized on the surfaces of derivatized quartz optical fibers to create an optical DNA biosensor; the covalently immobilized oligomers hybridized with complementary ssDNA/ssRNA from solution; hybridization detected by fluorescence (ethidium bromide); regenerable over ≥5 cycles; detection limit 86 ng/mL cDNA; 45 min/cycle. https://www.semanticscholar.org/paper/Fiber-optic-DNA-sensor-for-fluorometric-nucleic-Piunno-Krull/a4bcc0603f2420daff2419f023ef812b3313e5bb

• Stimpson, Hoijer, Hsieh, Jou, Gordon, Theriault, Gamble & Baldeschwieler, "Real-time detection of DNA hybridization and melting on oligonucleotide arrays by using optical wave guides," PNAS 92(14):6379–6383 (1995‑07‑03) — a two-dimensional optical waveguide DNA array; real-time measurement of hybridization/melting; imaging of the entire array simultaneously; label on the target generates signal only when bound; lower limit of detection 0.4 nM; single-base discrimination. https://www.pnas.org/doi/abs/10.1073/pnas.92.14.6379 ; https://pubmed.ncbi.nlm.nih.gov/[7603999](/patent/7603999)/

• US 5,690,894 / US 6,146,593 (Medical Research Council / Univ. of California), "High density array fabrication and readout method for a fiber optic biosensor," filed 1995‑05‑22 (→ § 102(e), effective as of filing) — fiber optic arrays "might bear nucleic acid binding partners to which nucleic acids in the test sample might hybridize"; fibers specifically addressed at the transmission end so that "binding of a molecule to a particular biological binding partner is specifically detectable"; expressly contemplates CGH two-label formats and nucleic acids "mapped to specific regions on one or more human chromosomes." https://patents.google.com/patent/US5690894 ; https://www.freepatentsonline.com/EP0879299.html

• Saiki et al., PNAS 86:6230 (1989) — genetic analysis with immobilized sequence-specific oligonucleotide probes.

• Fodor et al., Science 251:767 (1991); Fodor et al., Nature 364:555 (1993); Pease et al., PNAS 91:5022 (1994); Lipshutz et al., BioTechniques 19:442 (1995) — light-directed, spatially addressable high-density oligonucleotide arrays with fluorescently labeled targets.

• Schena, Shalon, Davis & Brown, Science 270:467–470 (1995) — cDNA microarray, quantitative gene-expression analysis with two-color fluorescence in a mixed target sample.

• Chee et al., Science 274:610 (1996); Hacia et al., Nature Genetics 14:441 (1996); Cronin et al., Hum. Mutat. 7:244 (1996) — high-density oligonucleotide probe arrays used to interrogate mixed samples for sequence variation.

• Drmanac et al. (1990) — sequencing by oligonucleotide hybridization on ordered arrays.

• EP 0 478 319 A1 (Toshiba) — gene detection method (appears on the page's own Patent-Art list).

• WO 93/02360 (Transmed) and WO 97/14028 (Luminex) — simultaneous/multiplexed analysis of multiple analytes (both on the page's Patent-Art list).

• US 5,856,484 (Sarnoff) — "Massively Parallel Detection" (on the page's Patent-Art list).

2.5 Walt-group fiber-array method publications (all § 102(b))

• Barnard & Walt, Nature 353:338–340 (1991) — fiber-optic chemical sensor with discrete sensing sites on a single fiber.
• Bronk & Walt, Anal. Chem. 66:3519 (1994) — patterned sensor arrays photodeposited on a polymer-coated imaging fiber via discrete illumination.
• Healey & Walt, Anal. Chem. 67:4471 (1995) — "selective photodeposition of analyte-sensitive polymer matrices on optical imaging fibers … An array of … matrices are fabricated on the same fiber … captured with a CCD camera." (PMID 8633784)
• Healey, Foran & Walt, Science 269:1078–1080 (1995) — "Photodeposition of micrometer-scale polymer patterns on optical imaging fibers … spots of 2.5 μm diameter spaced 4.5 μm apart." (PMID 7652555) — directly supplies the "individual specie deposits in aligned organization at differing spatial positions" limitation.
• Li & Walt, Anal. Chem. 67:3746 (1995) — dual-analyte sensor; "Each sensing site is an individual polymer cone covalently attached to the activated fiber surface using localized photopolymerization … fluorescence images of both sensing sites are captured with a CCD camera." (PMID 8644922)
• Bronk, Michael, Pantano & Walt, Anal. Chem. 67:2750 (1995) — arrays "containing approximately 6000 optical sensors" on a single imaging fiber, imaged through an epifluorescence microscope + CCD. (PMID 8779411)

Why this cluster matters: it establishes, before the critical date, that (i) thousands of spatially resolved, independently addressable deposits could be photopolymerized on a fiber face; (ii) the deposited material could be any reagent-doped polymer (pH dye, O₂ dye, enzyme, antibody); and (iii) the readout was CCD imaging of the whole face. Reagent identity — dye vs. oligonucleotide — is the only variable left for the '845 to supply.

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3. Element-by-element mapping of the three working claims

Immediate observation: with the sole exception of the reagent identity in (d) and the label placement in (e), every structural element of all three working claims is disclosed verbatim in US 5,244,636 and US 5,250,264, and both (d) and (e) are supplied by Piunno 1995 and US 5,690,894 in the fiber-optic context.

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4. Combination I — C1 (single clad fiber strand) is obvious

Primary reference

Piunno et al. 1995, Anal. Chem. 67(15):2635–2643.

Piunno discloses: a quartz optical fiber; single-stranded oligonucleotide probes covalently immobilized on the fiber surface; selective hybridization with a complementary target from solution; optical (fluorescence) detection; and regeneration for repeated cycles. Map onto C1: clad fiber with two optic end faces ✔; single species of ssDNA as a fixed probe on the fiber ✔; mobile complementary target ✔; joined identifying label ✔ (ethidium bromide/fluorophore reporting on the duplex); optical detection at the fiber ✔.

Secondary references

• Walt US 4,822,746 / US 5,114,864 / US 5,143,853 / US 5,252,494 — the single-fiber format: porous polymeric reaction matrix immobilized at the distal end, with the analyte permeating and reacting within the matrix, optically interrogated through the strand.
• Munkholm 1986; Jordan 1987 — the applicant's own admitted photopolymerizable-monomer-plus-biomolecule deposition chemistry.
• Healey & Walt 1995; Healey/Foran/Walt 1995 Science — micrometer-scale photodeposition of reagent-doped polymers on fiber faces.

Motivation to combine

1. Same field, same problem, same recognition of the problem. Both Piunno and Walt address "detect a specific species at a fiber tip optically." A PHOSITA seeking to make a reusable, immobilized-probe sensor would naturally look to both.
2. Piunno's express disadvantage invites the Walt improvement. Piunno's own paper reports a 45-minute hybridization cycle and 86 ng/mL detection limit; the art (Stimpson 1995) already reported real-time array measurement at 0.4 nM. There is a specific, articulated motivation to (i) increase surface area/signal through polymer-matrix immobilization and (ii) reduce cycle time.
3. The applicant's own spec concedes the combination is available: it states that the preferred immobilization route for these probes is photoactivation using Munkholm/Jordan monomer chemistry in admixture with an oligonucleotide. An applicant cannot concede that the depositing chemistry works with oligonucleotides and then claim the result as non-obvious.
4. Reasonable expectation of success. Oligonucleotides had been covalently attached to silica/quartz and to polymer matrices (Saiki 1989; Piunno 1995; Fodor 1991); biotin/avidin secondary labeling was routine. The result — a labeled duplex at a fiber tip producing a fluorescence change — was predictable.

§ 103 posture

C1 is, on this record, anticipated under § 102(b) by Piunno alone if the claim does not recite a specific detection architecture beyond "optical detection via a joined label at the strand end face"; at minimum it is obvious over Piunno in view of the single-fiber Walt patents and Munkholm/Jordan. C1 is the most vulnerable of the three working claims.

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5. Combination II — C2 (bundled array) is obvious

Primary references

• Walt US 5,244,636 + US 5,250,264 — bundle/array of individually clad fibers, spatially addressed deposits, imaging readout, photopolymerization fabrication.
• Ferguson, Boles, Adams & Walt, Nat. Biotechnol. 14(13):1681–1684 (Dec 1996) — "A bundle of optical fibers was assembled with each fiber carrying a different oligonucleotide probe immobilized on its distal end. Hybridization of fluorescently labeled complementary oligonucleotides to the array was monitored by observing the increase in fluorescence that accompanied binding. The approach enables fast (<10 min) and sensitive (10 nM) detection of multiple DNA sequences simultaneously…" https://pubmed.ncbi.nlm.nih.gov/[9634851](/patent/9634851)/

Important status flag on Ferguson 1996. It is the inventors' own publication, published December 1996 — i.e., within one year of the 1997‑05‑05 filing. It is therefore § 102(a) art, not § 102(b) art, and could in principle be removed by a Rule 131 swear-behind showing an earlier invention date. I nonetheless discuss it because (a) it demonstrates what the art actually contained, and (b) it is fatal to any argument that the <10 min / 10 nM / multiplexed results were "unexpected." The fallback for § 103 purposes is the combination below, which does not depend on Ferguson.

Fallback primary combination (all § 102(b))

US 5,244,636 + US 5,250,264 + Piunno 1995 + Saiki 1989 + EP 0 478 319 A1 (Toshiba) + US 4,999,306 / US 5,047,627 (the bundled-array art the applicant itself concedes).

Motivation to combine

1. The structural half is fully taught by the Walt patents, verbatim. The '636 claims already cover a bundle-like multi-fiber array with different spatially addressed deposits reacting specifically with one analyte each. Substituting an oligonucleotide for the "light energy absorbing dye" at each site, and using a labeled complementary nucleic acid with a "specific binding partner," is the classic substitution of one known element for another to obtain a predictable result (MPEP 2144.04(III)(A); KSR).
2. The chemistry half is fully taught by Piunno/Saiki/Toshiba. Saiki 1989 already placed multiple sequence-specific oligonucleotide probes on a solid support and hybridized labeled target; Piunno already did so on an optical fiber.
3. The art was explicitly converging on the same destination. Sarnoff's "Massively Parallel Detection" (1996), Luminex's "Multiplexed Analysis of Clinical Specimens" (WO 97/14028), and Transmed's "simultaneous analysis of multiple analytes" (WO 93/02360) are all on the page's own Patent-Art list and all point to the same goal. That is "design incentive / market forces" and "known technique to improve similar devices in the same way."
4. The bundled-array format itself is conceded. The '845 spec states that bundling single-core fibers is "conventionally known" and cites EP 88105676.6, US 5,047,627 and US 4,999,306.

§ 103 posture

C2 is obvious. The only conceivable non-obvious carve-out would be a dependent claim reciting something concrete and unexpected (e.g., a specific photopolymerizable formulation, a specific spatial resolution, a specific probe-density, or a specific competition-assay format) — but the abstract "in-situ hybridization zone" language of the independent claim provides no such hook.

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6. Combination III — C3 (preformed unitary coherent array, multiplexed) is obvious

This is the most sophisticated working claim. It is nonetheless the second most vulnerable because the Walt patents teach its structural preamble essentially verbatim.

Primary combination

US 5,244,636 (structure + apparatus/method claims) + US 5,250,264 (photopolymerization fabrication) + US 5,690,894 (nucleic-acid binding partners on a fiber optic array with addressed readout) + Piunno 1995 + Stimpson 1995 + Schena 1995 / Chee 1996 / Hacia 1996.

Why the combination is compelling

(1) The structural claim language is not merely "similar" — it is nearly identical. Compare:

• '845 C3: "a preformed, unitary fiber optic array comprising a plurality of individually clad, fiber optic strands disposed coaxially along their lengths and having two discrete optic array ends each of which is formed of multiple strand end faces, said preformed unitary fiber optic array being of determinable configuration and dimensions and said two discrete optic array ends presenting two discrete optic array surfaces for introduction and conveyance of light energy."
• '636 claim 1: "a preformed, unitary fiber optic array comprising a plurality of individually clad, fiber optical strands disposed co-axially along their lengths and having two discrete optic array ends each of which is formed of multiple strand end faces, said preformed, unitary fiber optic array being of determinable configuration and dimensions, said two discrete optic array ends of said preformed, unitary fiber optic array presenting two discrete optic array surfaces for introduction and conveyance of light energy."

Only the deposit species and the analyte definition differ.

(2) The '636 reference expressly contemplates nucleic acid binding partners. As reproduced from the equivalent disclosure, "In one embodiment, the fiber optics might bear nucleic acid binding partners to which nucleic acids in the test sample might hybridize," and the assay is described as "binding of a molecule to a particular biological binding partner is specifically detectable" by examining the addressed transmission ends. This is a teaching, suggestion, or motivation in the primary reference itself — the strongest form of KSR/In re Kahn evidence, and under MPEP 2144.05(I) a reference's own suggestion is dispositive.

(3) US 5,690,894 independently supplies the same teaching in the same sub-field. It discloses a fiber optic array bearing nucleic acid binding partners, addressed transmission ends, with specific detection of binding at a particular fiber, including two-label (CGH) formats and nucleic acids "mapped to specific regions on one or more human chromosomes." Its 1995‑05‑22 filing date gives it § 102(e) effect — and because it is not commonly owned with the '845, pre‑AIA § 103(c) cannot remove it.

(4) The multiplexing limitation is squarely in the art. Schena 1995 (quantitative expression profiling in a mixed target population), Chee 1996, and Hacia 1996 (mutation detection in mixed samples) each detect multiple different targets concurrently in one sample, which is exactly the "plurality … in a fluid sample containing a mixture of different oligonucleotide species … in a fluid mixture containing alternative mobile complementary target species" limitation.

(5) The label limitation is squarely in the art. "At least one light energy absorbing dye of known spectral characteristics" is met by the fluorescein/two-color labels of Fodor/Pease/Schena/Hacia, the particulate label of Stimpson, the ethidium bromide of Piunno, the up-converting reporters of EP 0 723 146 (SRI, on the page's list), and the biotin→avidin-dye indirect route the applicant admits is conventional.

(6) The deposition-at-differing-spatial-positions limitation is squarely in the art. Healey/Foran/Walt Science 1995 gives 2.5 μm deposits spaced 4.5 μm apart; Li & Walt 1995 gives covalently photopolymerized polymer cones "at defined positions" on the distal end of an imaging fiber, captured with a CCD; Bronk et al. 1995 gives ~6000 sensors on one imaging fiber. If a 2.5 μm spot can be a pH indicator, nothing in the art suggests it cannot be an oligonucleotide — particularly when the applicant concedes Munkholm/Jordan describe exactly the photopolymerization of a monomer admixture with an oligonucleotide.

Motivation to combine (articulated in KSR form)

§ 103 posture

C3 is obvious. The single strongest line of attack is US 5,244,636 + US 5,250,264 + US 5,690,894 + Stimpson 1995 + Schena 1995, with Piunno 1995 and Fodor/Pease 1994 as corroborating label/probe chemistry. All five primaries are § 102(b) (or § 102(e)) art as of the critical date, and none is removable by § 103(c) or a Rule 131 declaration.

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7. Secondary considerations — and why they likely do not rebut

The specification asserts four advantages: (i) <10 min detection; (ii) ~0.01–0.1 nM sensitivity; (iii) nanoliter-to-µL sample volumes; (iv) real-time monitoring without separating the sensor from the sample. Each is undercut by the art:

Two structural problems with the secondary-considerations case:

1. Nexus/claim-limitation problem. These advantages are recited in the specification, not (so far as I can determine) in the claims. An advantage must be coextensive with the claim to carry rebuttal weight (In re Kao; MPEP 716.01(c)).
2. Priority problem for the sensitizing-advantage argument. The "fast, sensitive, multiplexed" property was already published by the inventors themselves (Ferguson 1996) before the filing — an inventor's own disclosure cannot establish non-obviousness unless it too falls within the grace period and the invention date is asserted earlier, which is a Rule 131 issue, not a § 103 rebuttal in the first instance.

Where the patent might have survived (worth probing if a validity challenge were live): a dependent claim reciting a specific deposit geometry, a specific photopolymerizable monomer mixture (e.g., acrylamide/N,N′-methylenebisacrylamide plus an acrylate-derivatized oligonucleotide), a specific spatial resolution or spot-size/spacing, a specific competitive-assay protocol, or a specific regeneration/denaturation sequence. Those are the kind of concrete, non-routine recitations that can survive an obviousness attack even where the genus is not novel.

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8. § 102 anticipation overlaps to keep in view

Because the analysis above is close to the anticipation line, I flag these expressly (do not present them as findings without the verbatim claims):

• C1 vs. Piunno 1995 — Piunno appears to disclose every material element. If the claim recites nothing beyond "fiber + immobilized single oligo species + labeled complementary target + optical readout," it is anticipated.
• C3 vs. US 5,244,636 (structure) + US 5,690,894 (nucleic-acid binding partners on an addressed fiber array) — together these read on the structural preamble and the nucleic-acid-probe function. Whether this is anticipation or "merely" obviousness depends on whether a single reference contains the whole arrangement; it is more safely pleaded as a § 103 combination.
• C3 vs. US 5,690,894 alone — if the '894 discloses a fiber-optic array bearing nucleic-acid binding partners readable at addressed transmission ends, it may anticipate the array-plus-nucleic-acid combination, but it is unlikely to disclose the coherent preformed unitary phrasing used here. Again, § 103 is the safer ground.
• C2 vs. Ferguson 1996 — anticipates on its face but is the inventors' own § 102(a) publication; use only with a Rule 131 caveat.

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9. Legal and evidentiary notes on the art's status

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10. Bottom line and confidence

Conclusion. On the prior art visible on this page and in the surrounding record, all three working independent claims of US 6,406,845 are invalid as obvious under pre-AIA 35 U.S.C. § 103(a), and C1 and C3 are close enough to the anticipation line that § 102 should be pleaded in the alternative.

• C1 (single strand): obvious over Piunno 1995, alone or in view of the single-fiber Walt patents and the applicant-admitted Munkholm/Jordan photodeposition chemistry. Very high confidence, subject to the claim-text caveat.
• C2 (bundled array): obvious over US 5,244,636 + US 5,250,264 + Piunno 1995 + Saiki 1989 + EP 0 478 319 A1, with the page's own conceded bundling art (US 4,999,306; US 5,047,627; EP 88105676.6). High confidence.
• C3 (preformed unitary array, multiplexed): obvious over US 5,244,636 + US 5,250,264 + US 5,690,894 + Stimpson 1995 + Schena 1995 (corroborated by Fodor 1991 / Pease 1994 / Chee 1996 / Hacia 1996 / Piunno 1995). High confidence, and the Walt patents' near-verbatim structural recitations make this the most decisive combination in the record.

The single most damaging fact for the patent is that US 5,244,636 and US 5,250,264 — same assignee, same inventors' group, issued more than three years before the '845 was filed — recite the preformed unitary fiber optic array, the two discrete optic array surfaces for introduction and conveyance of light energy, the spatially addressed deposits at differing positions on multiple strand end faces, the photopolymerization fabrication method, and the means for detecting emerging light energy, in language that the '845 repeats almost verbatim. The '845's contribution reduces to substituting a known binding-pair chemistry (oligonucleotide/oligonucleotide) for the known dye/analyte chemistry of the same apparatus — a substitution the '636 specification itself suggests.

Explicit uncertainties I am not papering over:

1. I do not have the verbatim numbered claims of the '845; the mapping above uses the three specification "aspects" as proxies. If the claims contain unexpected narrowing language (specific monomer systems, specific spot dimensions, specific regeneration protocols, or specific quantitative limits), the confidence levels would need to be revisited claim-by-claim.
2. I have not verified the full 57-item "Patent Art" list on the Unified Patents page — only the ~22 entries visible in the retrieved snippet. The remaining entries may add or duplicate references; they are unlikely to weaken the above.
3. Ferguson 1996 is the inventors' own § 102(a) publication. Any validity challenge built on it must account for a possible Rule 131 swear-behind. The Combination III fallback in §6 is deliberately constructed to not depend on Ferguson.
4. I found no PTAB or district-court validity determination on this patent (consistent with the previously generated litigation section, which located no litigation). This analysis is therefore a prospective, from-the-face-of-the-art opinion, not a report of an adjudicated holding — and, per the operating rules, I am not asserting affirmative knowledge of a "never litigated" fact.

Primary sources cited: https://patents.google.com/patent/US6406845/en · https://portal.unifiedpatents.com/patents/patent/US-6406845-B1 · https://insight.rpxcorp.com/patent/US5244636A · https://insight.rpxcorp.com/patent/US5250264A · https://portal.unifiedpatents.com/patents/patent/US-5250264-A · https://FreePatentsOnline.com/5252494.html · https://patents.google.com/patent/US5690894 · https://www.freepatentsonline.com/EP0879299.html · https://www.pnas.org/doi/abs/10.1073/pnas.92.14.6379 · https://pubmed.ncbi.nlm.nih.gov/7603999/ · https://pubmed.ncbi.nlm.nih.gov/9634851/ · https://www.semanticscholar.org/paper/Fiber-optic-DNA-sensor-for-fluorometric-nucleic-Piunno-Krull/a4bcc0603f2420daff2419f023ef812b3313e5bb · https://patentimages.storage.googleapis.com/21/fb/ca/07b690907b0f84/US6482593.pdf