US 12174107

Here's a concise summary of US patent 12174107:

US Patent 12174107

• Title: Flow cytometer
• Assignee: Beckman Coulter Inc [cite: Original Assignee, Current Assignee]
• Inventor: Yong Qin Chen [cite: Inventor]
• Filing Date: September 3, 2024 [cite: Filing date]
• Issue Date: December 24, 2024 [cite: Publication date, Application granted]
• Abstract: A flow cytometer featuring a wavelength division multiplexer (WDM) that includes an extended light source forming an object. A collimating optical element captures light from this source, projecting a magnified image as a first light beam. A first focusing optical element then concentrates this first light beam to a size smaller than the original object, directing it to a first semiconductor detector. [cite: Abstract]

Plain-Language Overview of Independent Claims:

• Claim 1: This claim describes a flow cytometer system. It includes a laser diode (LD) optical system for shining light into a viewing area where sample particles flow, encased by a sheath fluid. It also has a special microscope objective to image light scattered and fluoresced by particles, a fluid system to provide a pulsation-free sheath fluid, a peristaltic pump for the sample liquid, and a wavelength division multiplexer (WDM) to separate the light emitted from the viewing zone into different colors.
• Claim 16: This claim outlines a method for creating an elliptical laser beam for a flow cytometer. The steps involve: emitting a diverging elliptical beam from an LD, collimating it so its minor axis is parallel to the particle flow, reducing the beam's size so its major axis (perpendicular to flow) is narrower than the sheath flow, and using a cylindrical lens near the viewing zone with its axis perpendicular to the flow.
• Claim 26: This claim details a method for analyzing microscopic species using a specialized microscope objective. The objective has a concave mirror and an aberration corrector plate (an aspheric lens with distinct optical powers in different zones) with the viewing zone in between. The method involves forming an optical image of the viewing zone outside this device.
• Claim 35: This claim defines a fluidic subsystem designed to deliver a liquid flow without pulsations. It includes a liquid pump drawing from a reservoir and a T-coupling. A first portion of the liquid from the pump goes through a bypass back to the reservoir, while a second portion flows through a particle filter to the flow cytometer's viewing zone.
• Claim 42: This claim describes a method for operating the pulsation-free fluidic subsystem of Claim 35. It involves pumping liquid, splitting it at a T-coupling, directing one fraction back to the reservoir via a bypass, and sending another fraction through a particle filter to the viewing zone.
• Claim 48: This claim describes a peristaltic pump designed to minimize pulsations. It includes a pump housing with a curved track, rollers on a rotor, and a compressible tube. The track has an exit section and at least one pumping section, where the tube expands at the exit and is fully compressed by rollers in the pumping sections.
• Claim 55: This claim describes a method for operating the peristaltic pump of Claim 48. It involves rotating rollers within a curved track to compress a tube, where the tube expands at an exit section and is fully compressed by rollers in pumping sections.
• Claim 62: This claim defines a wavelength division multiplexer (WDM). It includes a collimating optical element that creates a magnified image, at least one dichroic filter between the element and its image to split light into two color branches, a focusing element in one branch to focus light to a spot less than 1.0 mm, and an image relay element in the other branch to create a unit-magnification image.
• Claim 68: This claim describes a method for separating light into colored bands using the WDM of Claim 62. The method involves magnifying light to create an image, using a dichroic filter to split the light into two color branches, focusing one branch to a small spot, and relaying the image of the collimating element in the other branch with unit magnification.
• Claim 74: This claim broadly covers a flow cytometer incorporating a specific wavelength division multiplexer (WDM) system. The WDM includes an extended light source, a collimating optical element to project a magnified light beam, and a focusing element to direct this beam to a semiconductor detector at a size smaller than the original object.
• Claim 75: This claim describes a flow cytometer that has a viewing zone for illuminating particles and a composite microscope objective. The objective includes a concave mirror to gather light scattered or fluoresced by the particle and reflect it, and an aberration corrector plate to minimize optical distortions in that reflected light.
• Claim 77: This claim describes a flow cytometer with a fluidic system comprising a liquid pump and a T-coupling. The liquid from the pump is split: one fraction bypasses back to the reservoir, and the other passes through a particle filter to the fluidic system's outlet.
• Claim 78: This claim defines a flow cytometer incorporating a peristaltic pump. The pump has a housing with a curved track, rollers on a rotor, and a compressible tube. It specifically features a recess section between pumping sections where the tube is not fully closed.
• Claim 82: This claim describes a flow cytometer featuring a laser diode (LD) system. This system includes an LD emitting a diverging elliptical beam, a collimating lens to make it a collimated elliptical beam (minor axis parallel to particle flow), a beam compressing element to make the major axis narrower than the sheath flow, and a cylindrical focusing element positioned adjacent to the viewing zone with its axis perpendicular to the particle flow direction.

Litigation Information:
As of April 26, 2026, the patent family for US12174107B1 is involved in litigation. A PTAB case, PGR2025-00088, has been filed but was not instituted on procedural grounds. Additionally, a US case, 1:24-cv-00945, has been filed in the Delaware District Court. [cite: Family has litigation, First worldwide family litigation filed, PTAB case PGR2025-00088 filed (Not Instituted - Procedural), US case filed in Delaware District Court] No specific dockets related to US12174107B1 were found in CAFC 2026 searches, suggesting any appeals related to this patent have not yet reached the Federal Circuit.

As of April 26, 2026, the following litigation involving US patent 12174107 is known:

1. District Court Litigation

• Plaintiff(s): Beckman Coulter, Inc.
• Defendant(s): Cytek Biosciences, Inc.
• Jurisdiction: U.S. District Court for the District of Delaware
• Case Number: 1:24-cv-00945 (Unified Patents references "1:24-cv-00945")
• Filing Date: August 2024 (Patent Owner commenced litigation in August 2024)
• Outcome/Current Status: Active. A jury trial is scheduled for August 17, 2026. The district court has denied requests to adjourn the trial.

2. Post-Grant Review (PGR) at the PTAB

• Petitioner: Cytek Biosciences, Inc.
• Patent Owner: Beckman Coulter, Inc.
• Jurisdiction: Patent Trial and Appeal Board (PTAB) of the USPTO
• Case Number: PGR2025-00088
• Filing Date: Not explicitly stated, but the "Patent Owner's Request for Discretionary Denial" is dated September 17, 2025.
• Outcome/Current Status: Not Instituted - Procedural. The PTAB has a projected final written decision deadline of January 2027, but the district court trial is set for August 2026, leading to arguments about the duplication of proceedings.

Proceedings overview

One Post-Grant Review (PGR) proceeding has been filed against US patent 12174107. The PGR was denied institution on procedural grounds, meaning no claims were invalidated. This gives a defendant a posture where the patent has not been challenged on its merits at the PTAB, but the specific grounds raised in the petition for PGR2025-00088 cannot be raised again by the same petitioner or their privies.

PGR2025-00088 — Cytek Biosciences, Inc. v. Beckman Coulter, Inc.

• Type: Post-Grant Review
• Filed: 2025-09-23
• Status: Discretionary Denial (Institution denied on procedural grounds due to ongoing parallel district court litigation).
• Judge panel: Not publicly available in the provided information, but Jeffrey N. Fredman and John G. New are known PTAB judges with activity in PGRs around this time.
• Petition grounds: The petition challenged the validity of claims of U.S. Patent No. 12,174,107. The Patent Owner's request for discretionary denial specifically mentions that the Petitioner's arguments from this PGR were incorporated into its § 112 contentions in the district court.
• Institution decision: Denied on 2026-03-17. The PTAB denied institution based on discretionary considerations under 35 U.S.C. § 314(a), citing the advanced stage of a parallel district court litigation where a jury trial is scheduled for August 17, 2026, which is more than five months before the PTAB's projected final written decision deadline of January 2027. The district court had previously denied requests to adjourn the trial. The PTAB's decision aligns with its policy to deny institution when a parallel district court proceeding is likely to reach a final decision on patentability before the PTAB.
• Final Written Decision: Not issued, as institution was denied.
• Settlement / termination: Not applicable, as institution was denied.
• Appeal: No appeal of a Final Written Decision, as none was issued.
• Defensive value: The patent claims were not reviewed on their merits by the PTAB in this proceeding. However, Cytek Biosciences, Inc. (and its privies) are estopped from raising the same invalidity grounds (and any grounds that could have been raised) from this petition in future PTAB proceedings. For other potential defendants, the patent claims remain untested at the PTAB, but the arguments regarding the proximity of a district court trial may provide a precedent for discretionary denial if similar circumstances arise.

Strategic summary

Only one PGR, PGR2025-00088, has been filed against US patent 12174107 by Cytek Biosciences, Inc. The petition was denied institution on procedural grounds, specifically due to the ongoing parallel district court litigation with a jury trial scheduled for August 17, 2026. This means that no claims of 12174107 have been formally challenged or invalidated by the PTAB.

For a defendant currently facing assertion of this patent, the patent claims are still considered "untested" in terms of a merits-based PTAB review. The denial of institution in PGR2025-00088 was a discretionary decision based on the advanced stage of the district court case. This scenario highlights the PTAB's discretion to deny institution under certain circumstances to avoid duplicative efforts with district court litigation.

Regarding estoppel, Cytek Biosciences, Inc. (and any parties in privy with them) would be estopped under 35 U.S.C. § 315(e)(2) from re-raising any ground that was raised or reasonably could have been raised in the PGR petition in future PTAB proceedings against patent 12174107. Other potential petitioners would not be estopped by this denial from challenging the patent on different grounds or even the same grounds if they are not in privy with Cytek. The patent owner, Beckman Coulter, Inc., has successfully fended off this initial PTAB challenge, but the validity of the claims on the merits has not yet been adjudicated by the PTAB.

Recommended next steps

If you are a defendant facing assertion of US patent 12174107, be aware that while a PGR was filed, institution was denied on procedural grounds. Therefore, no claims have been invalidated. Cytek Biosciences, Inc. is estopped from re-raising the grounds presented in PGR2025-00088. Other potential petitioners are not bound by this estoppel.

The district court jury trial for the parallel litigation (1:24-cv-00945 in the U.S. District Court for the District of Delaware) is scheduled for August 17, 2026. The outcome of this trial will be highly significant. Consider monitoring this district court case closely as it may provide insights into the strength of the patent and potential invalidity arguments.

The absence of any PTAB activity where claims were addressed on their merits means that the patent's claims remain a live issue in litigation.

Inventors

• Yong Qin Chen: Employer: IRIS International, Inc. (at the time of priority date/filing of related applications).

Original assignee

The entity named on the issued patent is Beckman Coulter Inc.. Beckman Coulter Inc. is a leading global developer, manufacturer, and marketer of products that simplify, automate, and innovate complex biomedical testing. They ship a wide range of products, including flow cytometers that embody the claims of this patent. Beckman Coulter Inc. is currently operating as a subsidiary of Danaher Corporation.

Assignment timeline

• 2024-09-03 (executed) / recorded 2024-09-03 — Reel 007135/0793

  • Conveyance: Assignment
  • Assignor: CHEN, YONG QIN
  • Assignee: IRIS INTERNATIONAL, INC.
  • Correspondent: BRENT D. REYNOLDS, BECKMAN COULTER, INC., 250 S. KRAEMER BLVD., BREA, CALIFORNIA, UNITED STATES, 92821
  • Context: Inventor assigned patent rights to IRIS International, Inc.

• 2024-09-03 (executed) / recorded 2024-09-03 — Reel 007135/0793

  • Conveyance: Assignment
  • Assignor: IRIS INTERNATIONAL, INC.
  • Assignee: BECKMAN COULTER, INC.
  • Correspondent: BRENT D. REYNOLDS, BECKMAN COULTER, INC., 250 S. KRAEMER BLVD., BREA, CALIFORNIA, UNITED STATES, 92821. This correspondent recurs in this chain.
  • Context: IRIS International, Inc. assigned patent rights to Beckman Coulter, Inc.

Timeline diagram

timeline
    title Ownership of US 12174107
    2012 : Priority date
    2013 : PCT application filed
    2024 : Inventor assigned to Iris Intl
         : Iris Intl assigned to Beckman Coulter
         : Application filed by Beckman Coulter Inc
         : Patent granted

NPE / troll-pattern signals

1. Shell-entity transfer — not present. Both IRIS International, Inc. and Beckman Coulter, Inc. are operating companies.
2. Known asserter in the chain — not present. Neither IRIS International, Inc. nor Beckman Coulter, Inc. are listed on public NPE lists.
3. Repeat correspondent across the chain — present. Brent D. Reynolds of Beckman Coulter, Inc. is listed as the correspondent for both assignments recorded on 2024-09-03 (Reel 007135/0793).
4. Cascading transfers — not present. There are two assignments on the same day, but they represent a single transfer from the inventor through an acquired entity to the current operating company.
5. Pre-litigation transfer — not present. The assignments were recorded on 2024-09-03, and litigation commenced in August 2024. While close, the assignments occurred before the publication date of the granted patent and likely reflect the proper recording of ownership prior to assertion.
6. Bankruptcy fire-sale — not present. No evidence of bankruptcy proceedings for the assignors.
7. Privateering — unclear. There is no public information to suggest Beckman Coulter Inc. is using an NPE for assertion.
8. Defensive aggregator (anti-NPE) — not present. The chain ends with Beckman Coulter, Inc., an operating company.

Verdict

Operating-company assertion. The assignment records (Reel 007135/0793) show the patent was assigned from the inventor to IRIS International, Inc., and then from IRIS International, Inc. to Beckman Coulter, Inc. on the same day (2024-09-03). Beckman Coulter, Inc. is an operating company that manufactures and sells flow cytometers, and the current litigation appears to be an assertion by an operating company against a competitor.

USPTO Assignment Center search: https://assignmentcenter.uspto.gov/ (search for patent number 12174107).

US patent 12174107, titled "Flow cytometer," was filed on September 3, 2024, and published on December 24, 2024. It is currently active and is assigned to Beckman Coulter Inc. The patent claims priority from several provisional applications filed in 2012 and 2013, as well as an international PCT application filed on May 30, 2013.

The patent generally relates to improved flow cytometers and their subassemblies, including diode laser-based optical systems, composite microscope objectives, fluidic systems, pulseless peristaltic pumps, and wavelength division multiplexing (WDM) systems.

Based on available information, the following prior art has been identified as most relevant to US patent 12174107, particularly through litigation and PTAB proceedings concerning related patent families:

1. U.S. Patent No. 6,683,314 (Oostman)

• Full Citation: US 6,683,314 B1
• Publication/Filing Date: The patent itself was granted on January 27, 2004, from an application filed on April 12, 2002.
• Brief Description: This patent describes wavelength division multiplexers (WDM) used in optical communication, which are noted to be almost identical in function and architecture to those described in 12174107. Specifically, Oostman's WDM system is discussed in the context of fluorescence light detection and utilizing dichroic filters.
• Potentially Anticipated Claim(s): This reference was asserted during the prosecution of a grandparent patent to 12174107 (specifically, the '443 patent) as obvious over Oostman and Capewell. It is also asserted by Cytek Biosciences, Inc. (Petitioner) against claims of the '107 patent in PGR2025-00088. While specific claims anticipated are not definitively stated in the provided text, the reference is broadly relevant to the WDM aspects of 12174107, particularly claims concerning the design and operation of dichroic filter arrangements and separation of light into color bands, as exemplified by claims 1, 2, 5, 6, 9, 10, 16, 17, 20-22, 26, 27, 28, and 29 which describe a WDM with an array of mirrors and filters and a zig-zag optical path for detecting light, and the use of focusing lenses and APDs.

2. U.S. Patent Publication No. 2004/0165828 (Capewell)

• Full Citation: US 2004/0165828 A1
• Publication/Filing Date: Published August 26, 2004.
• Brief Description: This patent publication is from the optical communications field and was combined with Oostman by examiners during the prosecution of a grandparent to 12174107.
• Potentially Anticipated Claim(s): Similar to Oostman, Capewell is relevant to the WDM aspects of 12174107. The examiner's reliance on combining optical communications prior art with flow cytometry prior art suggests its relevance to claims related to the WDM system, particularly where the WDM is configured to receive light from an optical fiber and separate it into distinctive color bands for detection by semiconductor detectors.

3. U.S. Patent No. 6,542,306 (Goodman)

• Full Citation: US 6,542,306 B1
• Publication/Filing Date: Granted April 1, 2003, from an application filed May 11, 2000.
• Brief Description: Goodman is another reference that examiners considered during prosecution, and it is asserted by the Petitioner in the PGR against 12174107.
• Potentially Anticipated Claim(s): While the specific claims are not detailed, its mention in the context of the PGR indicates its relevance to the claims of 12174107. The broader scope of Goodman's relevance in comparison to Oostman or Capewell is not explicitly stated.

4. U.S. Patent No. 7,505,131 (Roth-131)

• Full Citation: US 7,505,131 B2
• Publication/Filing Date: Granted March 17, 2009, from an application filed December 29, 2005.
• Brief Description: This patent was also considered by the examiner during prosecution and is associated with Luminex Corporation.
• Potentially Anticipated Claim(s): The specific claims challenged are not stated in the provided text. Its consideration during prosecution suggests relevance to various aspects of flow cytometry described in 12174107.

It's important to note that the provided text often discusses prior art in the context of the related U.S. Patent No. 11,703,443 (the '443 patent), U.S. Patent No. 10,330,582 (the '582 patent), and U.S. Patent No. 12,174,106 (the '106 patent), which are part of the same family and share the same specification and priority claims as 12174107. Therefore, prior art considered against these related patents is highly relevant to 12174107. The PTAB's discretionary denial in PGR2025-00088 was procedural and did not rule on the merits of the prior art arguments.

Obviousness Analysis of US Patent 12174107 Under 35 U.S.C. § 103

This analysis addresses the obviousness of US Patent 12174107, titled "Flow Cytometer," under 35 U.S.C. § 103, considering the effective prior art date of May 30, 2012, based on the earliest priority date cited in the patent. The patent broadly claims an improved flow cytometer comprising several enhanced subassemblies: a laser diode (LD) based optical subsystem, a composite microscope objective, a pulseless fluidic subsystem, a pulseless peristaltic pump, and a wavelength division multiplexer (WDM). Each of these components is presented as addressing known problems in the field of flow cytometry.

Identified Prior Art References and Their Publication Dates

The following prior art references are cited within US12174107 or were found during the analysis, all published before May 30, 2012:

• U.S. Pat. No. 5,788,927: Published August 3, 1998. Discusses collimating and expanding a Gaussian beam for flow cytometry.
• U.S. Pat. No. 6,713,019: Published March 30, 2004. Describes an LD-based optical subsystem for flow cytometry.
• U.S. Pat. No. 7,385,682: Published June 10, 2008. Mentions aspheric lenses for LD collimation.
• U.S. Pat. No. 7,561,267: Published July 14, 2009. Mentions aspheric lenses for LD collimation.
• U.S. Pat. No. 4,727,020: Published February 23, 1988. Discloses multi-laser excitation in flow cytometers and branched WDM configurations.
• U.S. Pat. No. 6,683,314: Published January 28, 2003. Mentions a "star configuration" for WDM.
• U.S. Pat. No. 6,510,007: Published December 23, 2002. Describes a microscope objective.
• U.S. Pat. No. 7,110,192: Published November 14, 2006. Describes a microscope objective.
• WO 01/27590: Published April 19, 2001. Discloses a spherical concave mirror objective.
• U.S. Provisional Patent Application Ser. No. 61/653,245: Filed May 30, 2012, entitled "Pulseless Peristaltic Pump."
• U.S. Provisional Patent Application Ser. No. 61/653,328: Filed May 30, 2012, entitled "Composite Microscope Objective with a Dispersion Compensation Plate."
• Practical Flow Cytometry, Howard M. Shapiro, Wiley (2003) ISBN 0471411256: A foundational text on flow cytometry.

Obviousness of Individual Subsystems

A person having ordinary skill in the art (PHOSITA) in flow cytometry would possess a strong motivation to improve various aspects of flow cytometer design to enhance performance, reliability, and ease of use.

1. LD-based Optical Subsystem
US12174107 claims an LD-based optical subsystem that directs an elliptical beam with its minor axis parallel to the flow direction, using a beam-compressing element for the major axis and a cylindrical focusing element (axis perpendicular to flow) to focus the minor axis. This configuration aims to provide a Gaussian-like intensity profile along the minor axis and an optimized width along the major axis, overcoming issues like "fringes" from LDs and astigmatism in prior art.

• Prior Art: U.S. Pat. No. 6,713,019 ("the '019 patent") addresses LD beam quality by orienting the slow axis (minor axis) parallel to the flow, then diffusing the beam perpendicular to the flow with a cylindrical lens before focusing with a spherical lens. However, this leads to astigmatic and wide beams. U.S. Pat. No. 5,788,927 teaches general collimation and focusing to an elliptical Gaussian beam.
• Motivation for Combination: A PHOSITA would be keenly aware of the problems with LD beam quality, specifically the fringes along the fast axis and the astigmatism/width issues introduced by the approach of U.S. Pat. No. 6,713,019. Given the general knowledge of cylindrical lenses for anamorphic beam shaping and focusing, it would be obvious to reconfigure the optical train. The PHOSITA would be motivated to exploit the smoother profile of the LD's slow axis along the flow direction (as recognized by the '019 patent) while actively focusing this axis with a cylindrical lens positioned for precise control, and using a separate element for the major axis, to produce a tight, non-astigmatic elliptical spot. This is an application of known optical principles to overcome specific, identified deficiencies in existing LD-based flow cytometer illumination systems.

2. Composite Microscope Objective
The patent describes a composite microscope objective with a concave mirror and an aspheric aberration corrector plate, where the viewing zone is located between them. This design is intended to provide a long working distance, large numerical aperture (NA), large field of view (FOV), and minimal chromatic aberration.

• Prior Art: WO 01/27590 discloses an objective design based on a spherical concave mirror, offering large NA and good on-axis image quality but poor off-axis characteristics. U.S. Pat. Nos. 6,510,007 and 7,110,192 describe objectives using modified apochromats with gel-coupled or epoxy bonded lenses, which sacrificed image quality. Aspheric lenses are generally known for aberration correction in optical systems, as indicated by their mention in U.S. Pat. Nos. 7,385,682 and 7,561,267 for LD collimation.
• Motivation for Combination: To address the "poor off-axis characteristics" of mirror-based objectives like that in WO 01/27590, a PHOSITA would be motivated to employ known aberration correction techniques. The use of aspheric lenses for correcting various optical aberrations, including off-axis aberrations, is a well-established optical design principle. Combining the light-gathering capability of a concave mirror with an aspheric corrector plate to improve image quality, particularly off-axis performance for applications requiring a large FOV (e.g., multiple laser spots as taught by U.S. Pat. No. 4,727,020), would be an obvious design choice. Placing the viewing zone between the mirror and the corrector plate is a specific geometric arrangement that an optical designer would explore for compactness and optical performance. The details of the aspheric lens's power zones (negative outer, positive inner) represent a specific application of known aspheric design principles to achieve the desired correction.

3. Fluidic Subsystem for Pulseless Sheath Flow
US12174107 details a fluidic subsystem using a liquid pump, a T-coupling with a bypass conduit back to the reservoir (lower fluidic resistance), and a sheath route to the viewing zone that includes a particle filter. Critically, the system is designed to trap air within the particle filter inlet and in a reservoir capsule (or tubing) between the T-coupling and the filter, where this trapped air acts as a fluidic capacitor to reduce pulsations.

• Prior Art: The problem of pulsations in liquid flow within flow cytometers is well-known (implicitly addressed by the very title of U.S. Provisional Patent Application Ser. No. 61/653,245, "Pulseless Peristaltic Pump," filed on the same priority date). General fluid dynamics teaches that compressible elements, such as trapped air, can act as accumulators or dampeners to reduce pulsations. Bypass loops are standard engineering practice for flow and pressure regulation in fluid systems.
• Motivation for Combination: A PHOSITA tasked with creating a "pulsation-free" or "pulseless" liquid flow for flow cytometry (a stated goal of the '245 provisional) would immediately consider methods to dampen pulsations, especially those from common pumps like peristaltic pumps. Recognizing that air is compressible and can serve as a fluidic capacitor, it would be obvious to incorporate air chambers or deliberately design components to trap air to exploit this property. Designing a bypass loop to relieve excess pressure and further stabilize flow is a straightforward fluidic engineering solution. Combining these elements – a pump, a T-coupling, a bypass loop, and air-containing components (like a filter inlet or dedicated reservoir capsule/tubing) to act as fluidic capacitors – to achieve a stable, pulseless sheath flow would be obvious to a fluidics engineer.

4. Peristaltic Pump for Pulseless Liquid Flow
The peristaltic pump claimed in US12174107 includes rollers, a rotor, and a compressible tube against an arcuate track. The inventive feature lies in modifying the track with recesses that cause the tube to progressively decompress and then compress, maintaining a substantially invariant total fluid volume from the recess to the pump outlet. Alternatively, programmable motor speed is used to compensate for tube expansion.

• Prior Art: Peristaltic pumps are known, and their inherent pulsation is a widely recognized problem. The very existence of U.S. Provisional Patent Application Ser. No. 61/653,245, filed May 30, 2012, and titled "Pulseless Peristaltic Pump," strongly indicates that the problem of peristaltic pump pulsations and solutions for achieving pulseless flow were known and being actively developed at the priority date.
• Motivation for Combination: A PHOSITA in pump design would be motivated to address the known pulsation problem of peristaltic pumps. Modifying the geometry of the pump track to precisely control the compression and decompression of the tube and thus regulate fluid displacement is a direct application of mechanical design principles to achieve a desired flow characteristic. Similarly, using a variable-speed motor and programming its speed to counteract known pulsations or volume changes at the exit section is a standard application of control systems engineering. These solutions are predictable modifications of existing peristaltic pump designs aimed at solving a well-known problem.

5. Wavelength Division Multiplexing (WDM) System
US12174107 describes a WDM system featuring a cascaded unit-magnification image relay architecture with multiple optical elements to extend the collimated path without significant beam expansion. Dichroic filters are placed along this path, potentially in a zig-zag configuration, and are designed for consistent optical alignment via bonding to a holder with a reference surface.

• Prior Art: WDM techniques are "well-established in the optical communication industry" and were known to be "readily adapted for fluorescence light detection". U.S. Pat. No. 4,727,020 and U.S. Pat. No. 6,683,314 already disclose WDM configurations for flow cytometers (branched and star configurations, respectively). Unit-magnification image relay systems are a known optical principle for propagating beams or images over distances while maintaining beam characteristics.
• Motivation for Combination: A PHOSITA in optical design for flow cytometry would be motivated to create a WDM system that is more efficient, versatile, compact, and easily reconfigurable for separating multiple fluorescence signals. Recognizing the limitations of simply cascading dichroic filters in a non-relay system (e.g., beam expansion), it would be obvious to apply known unit-magnification image relay optics to extend the collimated path, allowing for the insertion of more filters (e.g., in a zig-zag configuration for compactness). The use of reference surfaces and templates for bonding optical filters to holders to ensure precise and repeatable alignment is a standard manufacturing and assembly practice for optical systems, aiming to improve manufacturability and serviceability.

Obviousness of the Overall Flow Cytometer System

The claims of US12174107 cover a flow cytometer that integrates these five improved subsystems. Flow cytometers are inherently complex systems that combine optical, fluidic, and detection components to analyze particles in a fluid stream.

• Motivation for Combination: A PHOSITA in the field of flow cytometry would understand that the performance of the overall system is dependent on the performance of its individual critical components. Therefore, there would be a strong and obvious motivation to integrate the best available or newly improved versions of each subsystem into a single flow cytometer to achieve a cumulative advantage in overall system performance. For instance, improved illumination from the LD optical subsystem, better light collection from the composite microscope objective, stable particle delivery from the pulseless fluidic system and peristaltic pump, and efficient signal separation from the WDM system all contribute to the well-understood goals of more accurate, reliable, and high-throughput flow cytometry. The integration of such improved components, each addressing a recognized challenge in its specific domain, into a comprehensive flow cytometer system would be a predictable result of routine engineering optimization and design choices to improve an existing technology.

In summary, while each subsystem of US12174107 presents specific engineering solutions, these solutions generally build upon known principles and address known problems in flow cytometry and related fields (optics, fluidics, pump design). The motivation to combine these individually improved components into a unified flow cytometer system would be clear to a PHOSITA seeking to enhance the performance and capabilities of such devices.