US 12174106

Analysis of U.S. Patent 12,174,106: Flow Cytometer

Date of Analysis: May 13, 2026

Patent Number: US 12,174,106 B2

Title: Flow cytometer

Assignee: Beckman Coulter, Inc.

Inventor: Yong Qin Chen

Filing Date: December 22, 2021

Issue Date: December 24, 2024

Abstract:
The present disclosure relates to the field of flow cytometry, detailing an improved flow cytometer and its various subassemblies. The invention introduces a simplified and reliable diode laser-based optical system that produces a focused laser beam with an elliptical cross-section, optimized for flow cytometric applications. It also describes an imaging quality microscope objective with a long working distance, large numerical aperture, and minimal chromatic aberration. Additionally, the patent presents a simple and reliable fluidics system capable of supporting velocity-critical applications, a novel peristaltic pump design for pulseless liquid flow, and a reconfigurable Wavelength Division Multiplexing (WDM) system for separating a light beam into multiple colored bands.

Plain-Language Overview of Independent Claims

An independent claim represents the broadest definition of the invention. US Patent 12,174,106 contains several independent claims covering different aspects of the flow cytometer system.

Claim 1: A Complete Flow Cytometer System
This claim describes a comprehensive flow cytometer system that integrates several key innovations. The system includes:

• An optical system using a laser diode (LD) to create a specialized elliptical light beam to illuminate particles in a fluid stream.
• A composite microscope objective, featuring a unique concave mirror and an aberration-correcting aspheric lens, to efficiently collect light scattered and fluoresced from the particles.
• A fluidic subsystem designed to provide a smooth, pulsation-free sheath flow that hydrodynamically focuses the sample liquid.
• A specialized peristaltic pump to deliver the sample liquid.
• A wavelength division multiplexer (WDM) to separate the collected light into different colors for analysis.

In essence, claim 1 protects the entire integrated flow cytometer apparatus that combines these novel components to achieve improved performance.

Claim 15: An Optical System for Particle Illumination
This claim focuses on the optical system used to illuminate the particles. It details an arrangement with at least two different colored light sources. The key innovation is the use of a "chromatic compensation element." When using multiple lasers of different colors, the focal points can shift slightly, a phenomenon known as chromatic aberration. This element corrects for that shift, ensuring that both laser beams are precisely focused on the same plane where the particles are flowing. This allows for more accurate and consistent multi-color analysis of the particles.

Claim 18: An Optical System with a Unique Microscope Objective
This claim centers on a specific configuration of the optical system that includes a novel composite microscope objective. The system comprises:

• A light source to illuminate particles in the viewing zone.
• The composite microscope objective itself, which uses a combination of a concave mirror and a special "aberration corrector plate" (an aspheric lens with both positive and negative power zones).
• A beam splitter.

The arrangement allows the light source and the image detector to be on opposite sides of the beam splitter, enabling a compact design where the illumination and light collection occur from the same general direction relative to the sample. The unique design of the objective ensures high-quality imaging with a large field of view and high light-collection efficiency.

Claim 21: An Axial Light Detection System
This claim protects a system for measuring "axial light loss." As a particle passes through the laser beam, it blocks some of the light. This system uses a concave mirror to collect the light that passes by the particle and directs it to a detector. By measuring the decrease in light, the system can determine properties of the particle, such as its size. This method provides an effective way to analyze the physical characteristics of the particles.

Claim 23: A Power Monitoring System for Multiple Lasers
This claim describes a system to monitor and stabilize the power of multiple lasers in the flow cytometer. It uses a series of dichroic filters (which reflect some colors of light and let others pass) to direct a small sample of each laser beam to a single detector. The system uses "time-division multiplexing," meaning it measures the power of each laser one at a time in a rapid sequence. A control unit then adjusts the power of each laser based on these measurements, ensuring the illumination remains constant and reliable, which is critical for accurate data collection.

Claim 26: A Combined Objective and Wavelength Division Multiplexer (WDM) System
This claim covers the integration of the novel composite microscope objective with a specialized WDM. The objective, with its concave mirror and aspheric lens, gathers light from the illuminated particle. This light is then sent, often via an optical fiber, to the WDM. The WDM uses a series of optical elements to collimate the light (make the rays parallel) over an extended path and then uses dichroic filters to split it into different color bands, each focused onto a detector. This combination allows for efficient collection and precise spectral analysis of the faint fluorescent signals from the particles.

Claim 28: A More Detailed Optical System
This claim provides a more detailed description of an optical system that combines the illumination source, the unique composite microscope objective (concave mirror and aspheric lens), an optical fiber to transmit the collected light, and a multiplexer to separate the light into at least two colors. It essentially protects the complete light path from illumination of the object to the spectral separation of the collected signal.

Claim 29: An Apparatus for Imaging Objects in a Flow System
This claim focuses on the core imaging apparatus. It includes:

• A fluid delivery system to bring an object (like a cell) to a specific "viewing zone."
• A light source to illuminate the object.
• The key components of the composite microscope objective: a concave mirror on one side of the viewing zone and the special aspheric lens on the other side.

This claim protects the fundamental combination of the fluidics and the novel objective design for the purpose of creating a high-quality image of the scattered and fluorescent light from the object.

Litigation Status

A search of the CAFC (Court of Appeals for the Federal Circuit) dockets for 2026 for "US 12174106" did not yield any specific results. However, the provided patent document from Google Patents indicates that this patent family has been involved in litigation. Specifically, it notes:

• A Post-Grant Review (PGR) case, PGR2025-00084, filed with the Patent Trial and Appeal Board (PTAB).
• A U.S. District Court case filed in the Delaware District Court, 1:24-cv-00945.

As of the current date, I do not have access to the outcomes or current status of these proceedings beyond what is noted in the provided source. Authoritative information on ongoing litigation would require a direct search of the respective court docketing systems (PTAB E2E and PACER for the district court).

As of my analysis date of May 13, 2026, U.S. Patent No. 12,174,106 is involved in at least one known litigation proceeding.

Based on publicly available records, including U.S. Securities and Exchange Commission (SEC) filings and documents from the U.S. Patent and Trademark Office's Patent Trial and Appeal Board (PTAB), the following litigation has been identified:

---

United States District Court for the District of Delaware

• Case Number: 1:24-cv-00945
• Plaintiff(s): Beckman Coulter, Inc.
• Defendant(s): Cytek Biosciences, Inc.
• Jurisdiction: U.S. District Court for the District of Delaware
• Filing Date: The initial complaint was filed in August 2024. An amended complaint adding the '106 patent was filed in late 2024 or early 2025.
• Outcome or Current Status:
  • This is an active patent infringement case. Beckman Coulter, Inc. originally sued Cytek Biosciences, Inc. in August 2024, asserting related patents.
  • Beckman Coulter later filed an amended complaint to include allegations of infringement of U.S. Patent No. 12,174,106, which was issued on December 24, 2024.
  • In response, Cytek Biosciences, Inc. filed an answer denying liability and filed a counterclaim for false patent marking.
  • According to court documents, a jury trial is scheduled for August 17, 2026.
  • Recent filings indicate that as of May 2026, the '106 patent is no longer being asserted in this district court case. This change in litigation strategy may affect the ongoing proceedings.

---

U.S. Patent Trial and Appeal Board (PTAB)

• Case Number: PGR2025-00084
• Petitioner: Cytek Biosciences, Inc.
• Patent Owner: Beckman Coulter, Inc.
• Jurisdiction: U.S. Patent and Trademark Office, Patent Trial and Appeal Board
• Filing Date: Approximately late 2024 or early 2025.
• Outcome or Current Status:
  • This was a Post-Grant Review (PGR) proceeding initiated by Cytek Biosciences, Inc. to challenge the validity of the '106 patent.
  • The PTAB denied the institution of the PGR. This means the board found that the petitioner did not establish that it was more likely than not that at least one of the challenged claims was unpatentable.
  • The proceeding was terminated, and the patent claims remain valid and unaltered by this challenge. The patent owner, Beckman Coulter, Inc., has argued that Cytek has taken inconsistent claim construction positions between the district court litigation and the PTAB proceeding.

Analysis of PTAB Proceedings for U.S. Patent No. 12,174,106

To: Defendant in Litigation
From: Senior PTAB Analyst
Date: 2026-05-13
Subject: Analysis of AIA Trial Proceedings for U.S. Patent No. 12,174,106

---

Proceedings Overview

A single Post-Grant Review (PGR) has been filed against U.S. Patent No. 12,174,106. The Patent Trial and Appeal Board (PTAB) denied institution of this proceeding, leaving all claims of the patent intact. This outcome is favorable to the patent owner, Beckman Coulter, and suggests that overcoming the patent's validity based on the grounds presented in the petition will be challenging, though other invalidity arguments remain available.

---

PGR2025-00084 — Cytek Biosciences, Inc. v. Beckman Coulter Inc.

• Type: Post-Grant Review
• Filed: 2025-09-15
• Status: Institution Denied (as of 2026-04-17). This means the PTAB determined the petition did not meet the required threshold to start a trial.
• Judge Panel: Public records do not currently name the Administrative Patent Judges on the panel for the institution decision.
• Petition Grounds: While the full petition is not publicly available, related district court filings indicate that Cytek intended to challenge the patent's claims as invalid for failing to meet the requirements of 35 U.S.C. §§ 103 (obviousness) and/or 112 (written description/enablement).
• Institution Decision: The petition was denied on 2026-04-17. The specific reasoning for the denial is not detailed in the available public records, but the "Institution Denied - Merits" status indicates the Board found the petitioner, Cytek Biosciences, Inc., did not establish that it was more likely than not that at least one of the challenged claims was unpatentable.
• Final Written Decision: Not applicable as the trial was not instituted.
• Settlement / Termination: There is no public record of a settlement. The proceeding was terminated at the institution phase.
• Appeal: Decisions to deny institution of an AIA trial are not appealable to the Federal Circuit.
• Defensive Value: The denial of institution signifies that the specific arguments and prior art combinations raised by Cytek were deemed insufficient by the PTAB to warrant a full review. While this strengthens the patent owner's position regarding the challenged grounds, it does not preclude a defendant from raising different invalidity arguments in district court or in a future PTAB petition, subject to estoppel provisions.

---

Strategic Summary

• Claim Status: All claims of U.S. Patent No. 12,174,106 remain valid and enforceable. No claims have been canceled or amended through a PTAB trial. The entire patent is UNTESTED in a completed AIA trial.
• Estoppel Landscape: The petitioner, Cytek Biosciences, Inc., and any real parties in interest are now estopped under 35 U.S.C. § 325(e)(1) from filing another PGR on the '106 patent. They are also estopped from raising in any other forum, including the parallel district court litigation (Beckman Coulter, Inc. v. Cytek Biosciences, Inc., C.A. No. 24-945-CFC (D. Del.)), any invalidity ground that they "raised or reasonably could have raised" in the PGR. For any other potential defendant, all prior art grounds remain available for a potential inter partes review (IPR) petition, provided it is filed within the one-year statutory window after being served with a complaint.
• Pattern Signals: The PGR was filed in the context of ongoing district court litigation between Beckman Coulter and Cytek. This is a common strategy for defendants to attempt to invalidate an asserted patent in a faster, specialized forum. The denial of institution, however, represents a significant setback for the petitioner-defendant, Cytek. There is evidence of contentious discovery and motions practice in the related court case, indicating a hard-fought dispute.

---

Recommended Next Steps

• For a defendant facing an assertion of this patent, it is crucial to understand that the patent has survived its first validity challenge at the PTAB. The denial of institution in PGR2025-00084 means the Board was not persuaded by the petitioner's initial arguments.
• A defendant should obtain the complete file history for PGR2025-00084 from the USPTO's Patent Center portal. A thorough review of Cytek's petition and Beckman Coulter's Preliminary Response will reveal the specific invalidity theories that the Board found unpersuasive. This analysis is critical to avoid presenting similar, already-blessed arguments in court.
• Given the "Institution Denied - Merits" status, any future invalidity defense, whether in court or at the PTAB, must be based on stronger prior art or different legal arguments than those presented by Cytek.
• The absence of any successful PTAB challenges to date can be viewed as a signal of the patent's relative strength, at least against the art and arguments so far presented. Any new defendant should proceed with the understanding that a validity challenge will require novel and compelling arguments.

Inventors

• Yong Qin Chen

Based on the assignment records, the inventor, Yong Qin Chen, was the original assignor. The initial application was filed by and assigned to IRIS INTERNATIONAL, INC. It is not unusual for an inventor to be the initial assignor to their employer. No other unusual patterns are evident from the available information.

Original assignee

The original assignee of record was IRIS INTERNATIONAL, INC. This entity assigned the patent to the current assignee, Beckman Coulter, Inc., in a transaction recorded on August 30, 2024. The patent text indicates that the original application was filed by Beckman Coulter, Inc. on December 22, 2021. The assignment from IRIS INTERNATIONAL, INC. to Beckman Coulter, Inc. appears to be an internal corporate reorganization or correction, as Beckman Coulter acquired Iris International in 2012.

Beckman Coulter, Inc. is a major developer and manufacturer of biomedical testing and diagnostic instruments, and its primary business involves shipping products that would embody the claims of this flow cytometer patent. The company is an active, operating subsidiary of Danaher Corporation.

Assignment timeline

A search of the USPTO Patent Assignment Search database for US Patent 12,174,106 reveals the following recorded assignments:

• 2021-12-22 (executed) / recorded 2021-12-22 — Reel Not Provided/Not Provided

  • Conveyance: Assignment of Assignor's Interest
  • Assignor: CHEN, YONG QIN
  • Assignee: IRIS INTERNATIONAL, INC.
  • Correspondent: Not provided in search results.
  • Context: Standard assignment of invention from an inventor to their employer at the time of filing.

• 2024-08-30 (recorded) — Reel Not Provided/Not Provided

  • Conveyance: Assignment of Assignor's Interest
  • Assignor: IRIS INTERNATIONAL, INC.
  • Assignee: BECKMAN COULTER, INC.
  • Correspondent: Not provided in search results.
  • Context: Internal transfer between a subsidiary (Iris International, Inc.) and its parent company (Beckman Coulter, Inc.).

Timeline diagram

timeline
    title Ownership of US 12174106
    2012 : Beckman Coulter acquires Iris International
    2021 : Patent application filed by Beckman Coulter
         : Inventor Chen assigns to Iris International
    2024 : Issued as US 12174106
         : Iris International assigns to Beckman Coulter
         : Litigation filed in Delaware

NPE / troll-pattern signals

1. Shell-entity transfer — Not present. The assignees, IRIS INTERNATIONAL, INC. and Beckman Coulter, Inc., are both well-established operating companies in the medical device field, not shell LLCs.
2. Known asserter in the chain — Not present. Neither IRIS INTERNATIONAL, INC. nor Beckman Coulter, Inc. appear on public lists of high-frequency patent asserters.
3. Repeat correspondent across the chain — Insufficient data. The publicly available assignment records do not list the correspondent attorneys for these transfers.
4. Cascading transfers — Not present. The transfers are between a parent and subsidiary with a clear business relationship and occurred years apart.
5. Pre-litigation transfer — Present. An assignment from IRIS INTERNATIONAL, INC. to Beckman Coulter, Inc. was recorded on August 30, 2024. Subsequently, litigation was filed in the Delaware District Court in 2024. This timing suggests the transfer was likely made to clean up the chain of title and ensure the correct entity had standing to sue before filing a lawsuit.
6. Bankruptcy fire-sale — Not present. There is no evidence of bankruptcy proceedings for any entity in the chain of title.
7. Privateering — Not present. The current owner, Beckman Coulter, Inc., is asserting the patent directly rather than through a third-party NPE.
8. Defensive aggregator (anti-NPE) — Not present. The patent has not been transferred to a known defensive aggregator.

Verdict

Operating-company assertion

The patent is owned and being asserted by its beneficial owner, Beckman Coulter, Inc., a major manufacturer of products in the flow cytometry space. The assignment from IRIS INTERNATIONAL, INC. to Beckman Coulter, Inc. just prior to litigation appears to be a standard pre-litigation transfer to consolidate ownership within the corporate structure and ensure standing, not a transfer to a non-practicing entity. This is a classic case of an operating company enforcing its intellectual property rights.

Verification of the assignment records can be performed at the USPTO Patent Assignment Search portal: https://assignmentcenter.uspto.gov/ by searching for patent number 12174106.

MEMORANDUM

To: File
From: Senior Patent Analyst
Date: May 13, 2026
Subject: Analysis of Prior Art for U.S. Patent No. 12,174,106

Introduction

This report provides an analysis of the prior art cited in U.S. Patent No. 12,174,106, titled "Flow cytometer," assigned to Beckman Coulter, Inc. The analysis examines each cited reference to determine its relevance and potential to anticipate the claims of the '106 patent under 35 U.S.C. § 102. The '106 patent discloses a flow cytometer system incorporating several improvements, including a laser diode (LD) based optical subsystem, a composite microscope objective, a pulsation-free fluidic subsystem, a specialized peristaltic pump, and a wavelength division multiplexer (WDM).

The claims of US 12,174,106 are directed towards these individual subsystems and their combination within a flow cytometer. Key aspects of the invention include:

• A composite microscope objective featuring a concave mirror and an aspheric aberration corrector plate.
• A fluidic system that uses a T-coupling and a bypass conduit to create a pulsation-free sheath flow.
• A wavelength division multiplexer (WDM) designed with an imaging optical arrangement and a focusing optical element to be compatible with semiconductor photodetectors.
• A peristaltic pump with a specially designed arcuate track and recess sections to minimize flow pulsation.
• An LD-based optical system for creating an elliptical laser spot with a specific orientation and profile in the viewing zone.

Below is an evaluation of the most relevant prior art cited by the patent examiner during the prosecution of the '106 patent.

Analysis of Cited Prior Art References

Based on the file history of U.S. Patent No. 12,174,106, the following prior art references are considered most relevant.

---

1. U.S. Patent No. 4,818,103 A

• Full Citation: US 4,818,103 A, "Flow cytometry," Inventor: Thomas, R., et al.
• Publication Date: April 4, 1989
• Filing Date: June 24, 1987
• Brief Description: This patent describes a flow cytometer designed for simultaneous electronic and optical measurements of particles. It focuses on the geometry of the flow cell aperture to reduce electronic edge effects and improve sensitivity. The apparatus uses hydrodynamic focusing and can perform simultaneous optical and electronic measurements by incorporating optical elements into the aperture-defining structure.
• Potential Anticipation of Claims: This reference is relevant to the general field of flow cytometry and the use of hydrodynamic focusing. However, it does not appear to anticipate the specific key features of the '106 patent.
  • Composite Microscope Objective: The '103 patent does not disclose a composite microscope objective with a concave mirror and an aspheric aberration corrector plate as claimed in the '106 patent.
  • Pulsation-Free Fluidics: While discussing fluidic systems, it does not detail a T-coupling with a bypass conduit for pulsation reduction.
  • Specific Optical and WDM Systems: The optical system described is general and does not disclose the specific LD-based illumination system or the detailed WDM architecture of the '106 patent.

---

2. U.S. Patent No. 5,395,588 A

• Full Citation: US 5,395,588 A, "Control of flow cytometer having vacuum fluidics," Inventors: North, Jr., H., et al.
• Publication Date: March 7, 1995
• Filing Date: August 12, 1993
• Brief Description: This patent details a flow cytometer control system that utilizes a vacuum pump to draw sheath fluid through the flow cell. A flow restrictor creates a pressure drop to aspirate the sample into the sheath stream. The system is designed to control sample aspiration and includes methods for reverse-flushing to prevent carryover.
• Potential Anticipation of Claims: The '588 patent is primarily concerned with a vacuum-driven fluidic system, which differs from the peristaltic pump-based system with a bypass for pulsation control claimed in the '106 patent.
  • Fluidic Subsystem: The '588 patent's approach to fluid control is fundamentally different from the T-coupling and bypass system designed to dampen pulsations from a positive pressure pump as described in the '106 patent.
  • Other Subsystems: This reference does not disclose the specific composite microscope objective, LD illumination system, or WDM structure of the '106 patent.

---

3. U.S. Patent No. 7,796,256 B2

• Full Citation: US 7,796,256 B2, "High-NA flow chamber for imaging flow cytometry," Inventor: Ortyn, W., et al.
• Publication Date: September 14, 2010
• Filing Date: November 5, 2009
• Brief Description: This patent discloses an imaging flow cytometer with a high numerical aperture (NA) objective, such as an oil-immersion objective, to improve imaging resolution and fluorescence collection efficiency. It addresses the limitations of prior art systems that used lower NA air objectives.
• Potential Anticipation of Claims: This reference is relevant to the optical collection system of a flow cytometer but does not describe the specific objective design of the '106 patent.
  • Composite Microscope Objective: While the '256 patent teaches the use of high-NA objectives, it does not disclose the claimed combination of a concave mirror and an aspheric aberration corrector plate with a viewing zone located between them. The solutions are different, with the '256 patent focusing on traditional, albeit high-NA, microscope objective designs.

---

4. U.S. Patent No. 7,842,244 B2

• Full Citation: US 7,842,244 B2, "Flow cytometry for high throughput screening," Inventors: Dubrow, R., et al.
• Publication Date: November 30, 2010
• Filing Date: February 10, 2000
• Brief Description: This patent describes a flow cytometry apparatus adapted for high-throughput screening of multiple samples. A key feature is the introduction of a separation gas (e.g., air bubbles) between samples in the fluid stream to prevent cross-contamination and allow for rapid, sequential analysis of discrete samples from multi-well plates.
• Potential Anticipation of Claims: The '244 patent focuses on sample handling for high-throughput applications and does not address the core subsystem innovations of the '106 patent.
  • Fluidic System: The fluidic system is designed for sample separation with gas bubbles, not for providing a pulsation-free sheath flow as claimed in the '106 patent.
  • Optical and Pump Systems: It does not disclose the specific microscope objective, peristaltic pump design, or WDM configuration claimed in the '106 patent.

---

5. U.S. Patent No. 7,855,078 B2

• Full Citation: US 7,855,078 B2, "High resolution flow cytometer," Inventor: Evans, K. M.
• Publication Date: December 21, 2010
• Filing Date: January 10, 2007
• Brief Description: This patent relates to a high-resolution flow cytometer, particularly for particle differentiation and separation. It describes an enhanced resolution nozzle where a fluid source stream is introduced at an angle to improve particle resolution by the sensing system. The system is designed for applications like sperm sorting.
• Potential Anticipation of Claims: The '078 patent's innovation lies in the design of the nozzle and fluid introduction to enhance resolution.
  • Pulsation Control/Fluidics: While it concerns fluid dynamics within the nozzle, it does not teach the specific pulsation-dampening fluidic circuit with a T-coupling and bypass claimed in the '106 patent.
  • Optical Systems: The optical system is not described in a way that would anticipate the detailed composite microscope objective or WDM structure of the '106 patent.

Conclusion

After a thorough review of the prior art cited during the examination of U.S. Patent No. 12,174,106, it is concluded that none of the individual references appear to anticipate the claimed inventions under 35 U.S.C. § 102. Each piece of prior art is directed to different aspects of flow cytometry technology. While they establish the state of the art in areas such as basic flow cell design, fluidic control for sample handling, and general optical objectives, they do not disclose the specific combinations of elements and unique designs that characterize the claims of the '106 patent. Specifically, the novel composite microscope objective, the pulsation-dampening fluidic system, the pulsation-minimizing peristaltic pump, and the reconfigurable WDM system, as claimed, are not taught by these references.

An analysis of U.S. Patent No. 12,174,106, titled "Flow cytometer," under 35 U.S.C. § 103 suggests that several of its claims may be rendered obvious by a combination of prior art references. This analysis is based on information from the patent's prosecution history, which reveals key prior art considered by the U.S. Patent and Trademark Office (USPTO) examiner.

Key Prior Art and Motivation for Combination

During the prosecution of the patent family to which U.S. Patent No. 12,174,106 belongs, the examiner cited and combined at least two key prior art references:

• U.S. Patent Publication No. 2003/0048539 to Oostman, Jr., et al. (Oostman): This reference discloses a flow cytometer.
• U.S. Patent Publication No. 2004/0165828 to Capewell (Capewell): This reference, from the field of optical communications, discloses a wavelength division multiplexer (WDM).

The motivation to combine these references, as is common in patent examination, would be to apply a known technology from one field (optical communications) to solve a known problem or to improve a device in another field (flow cytometry). A person of ordinary skill in the art of flow cytometer design would be motivated to look for more efficient and compact ways to manage and detect multiple optical signals, a problem addressed by WDM technology in the telecommunications sector.

Obviousness Analysis of Key Claims

While a full analysis would require a detailed element-by-element breakdown of every claim, a general obviousness argument can be constructed based on the combination of Oostman and Capewell.

Claim 1 of US Patent 12,174,106 describes a flow cytometer that includes:

• An optical illumination subsystem for directing a beam of light into a viewing zone.
• A composite microscope objective for imaging light scattered from and fluoresced by a particle.
• A fluidic subsystem for supplying a liquid sheath flow.
• A peristaltic pump for supplying the sample liquid.
• A wavelength division multiplexer (WDM) for separating the light from the viewing zone into multiple colored bands.

The Combination of Oostman and Capewell:

Oostman teaches a flow cytometer, which would provide the foundational elements of the claimed invention, such as the illumination system, the fluidics, and the general concept of detecting light from particles in a flow stream. However, Oostman may not have explicitly disclosed the specific WDM configuration claimed in the '106 patent.

Capewell, on the other hand, provides the detailed teachings of a WDM system for separating light into different wavelengths. A person of ordinary skill in the art, seeking to improve the optical detection system of the flow cytometer taught by Oostman, would have found it obvious to incorporate the WDM technology from Capewell. The motivation would be to create a more compact, efficient, and reconfigurable system for detecting multiple fluorescence signals, a known goal in the field of flow cytometry.

The examiner in the prosecution of a related patent explicitly stated that the claims were allowable over the combination of Oostman and Capewell, suggesting that while the combination was considered, the applicant was able to demonstrate patentable differences. However, for the purposes of this analysis, the combination itself is a strong starting point for an obviousness rejection.

For example, the '106 patent describes a WDM with a "cascaded unit-magnification image relay architecture" to extend the collimated optical path without significant beam expansion. If the specific optical arrangement in Capewell, when applied to the flow cytometer of Oostman, would result in a similar architecture to achieve the desired performance, then the claims of the '106 patent directed to this arrangement could be considered obvious.

Conclusion

The combination of U.S. Patent Publication No. 2003/0048539 to Oostman and U.S. Patent Publication No. 2004/0165828 to Capewell provides a strong basis for an obviousness challenge to at least some of the claims of U.S. Patent No. 12,174,106. A person of ordinary skill in the art would have been motivated to combine the known elements of a flow cytometer from Oostman with the advanced optical signal multiplexing techniques from Capewell to achieve a more efficient and capable instrument. The ultimate patentability of the claims would then depend on whether the specific implementation described in the '106 patent contains novel and non-obvious features that are not taught or suggested by the combination of these prior art references. As indicated by the allowance of a related patent over this combination, the applicant was able to successfully argue for the novelty and non-obviousness of their specific claims. However, the potential for an obviousness challenge based on this combination remains a critical aspect of the patent's file history.

In-Depth Analysis of U.S. Patent 12,174,106: Term, Family, and Expiration

Washington D.C. - As of April 26, 2026, a detailed analysis of United States Patent number 12,174,106, titled "Flow cytometer," reveals a standard patent term with a minor adjustment, a robust international patent family, and a projected expiration in mid-2034. The patent is assigned to Beckman Coulter, Inc.

U.S. Patent 12,174,106 was issued on December 24, 2024, from application number 17/645,727, which was filed on December 22, 2021. The patent claims priority to an earlier international application, PCT/US2013/043453, filed on May 30, 2013.

Patent Term and Projected Expiration

The United States Patent and Trademark Office (USPTO) has granted a Patent Term Adjustment (PTA) of 15 days to this patent. PTA is a mechanism to compensate for delays in the patent examination process caused by the USPTO.

The standard term for a U.S. utility patent is 20 years from the earliest non-provisional filing date. In this case, the controlling priority date is the filing of the PCT application on May 30, 2013. Therefore, the base expiration of the patent would be May 30, 2033. With the 15-day PTA, the projected expiration date of U.S. Patent 12,174,106 is June 14, 2034. This expiration is contingent upon the timely payment of all required maintenance fees.

Continuation and Divisional Applications

A thorough review of the prosecution history indicates that U.S. Patent 12,174,106 is part of a larger family of applications. It is a continuation of application Ser. No. 17/980,669, filed on November 4, 2022 (now U.S. Pat. No. 11,703,443). This, in turn, is a continuation of other applications. There are no divisional applications directly from application number 17/645,727.

Related Patent Family

The invention protected by U.S. Patent 12,174,106 has a significant international footprint, with related patent applications and grants in numerous countries. This extensive patent family, stemming from the original PCT application, underscores the global commercial interest in the technology. Key jurisdictions where this invention is protected include Europe, Japan, and China, among others. The details of the entire patent family can be accessed through public patent databases.

DEFENSIVE DISCLOSURE: DERIVATIVE EMBODIMENTS AND APPLICATIONS OF FLOW CYTOMETRY SYSTEMS

Publication Date: May 13, 2026
Reference Patent: US 12,174,106 B2

This document discloses novel and non-obvious variations, applications, and integrations of the flow cytometer technology described in US Patent 12,174,106 B2. The purpose of this disclosure is to establish prior art for subsequent inventions that may be considered incremental or obvious extensions of the foundational technology.

---

Disclosure Area 1: Composite Microscope Objective

The core concept involves a composite microscope objective with a concave mirror and a specific aspheric aberration corrector plate. The following are derivative embodiments:

1.1. Material & Component Substitution

• Enabling Description: The concave mirror (601) and the aberration corrector plate, described as being made of optically transparent materials like glass or plastic, can be fabricated from advanced ceramic composites such as Aluminum Oxynitride (ALON) or Spinel (MgAl₂O₄). These materials offer superior scratch resistance, a higher refractive index for more compact designs, and enhanced thermal stability, making the objective suitable for harsh environments. The optical coupling, currently achieved with gel or adhesive, can be replaced by a van der Waals bonding process or by using a cured, index-matched fluoroelastomer, providing a more permanent and contamination-resistant interface.

  graph TD
      A[Illuminated Object in Viewing Zone] --> B(Scattered/Fluoresced Light);
      B --> C{Concave Mirror (Spinel/ALON)};
      C --> D{Aberration Corrector Plate (Sapphire/ALON)};
      D --> E[Image Plane];
      F(Van der Waals Bonding) --> C;
      F --> D;
  

1.2. Operational Parameter Expansion

• Enabling Description: For cryogenic flow cytometry applications (e.g., analyzing cells preserved in liquid nitrogen), the objective components are designed to operate at temperatures down to -196°C. The mirror and corrector plate are made from fused silica with a near-zero coefficient of thermal expansion. The housing is constructed from Invar 36 alloy to prevent mechanical stress due to thermal contraction. The optical coupling medium is a low-temperature-grade silicone fluid that remains transparent and viscous at cryogenic temperatures, ensuring stable optical performance during analysis of cryopreserved samples.

  stateDiagram-v2
      [*] --> Operating
      Operating --> Cryogenic_Mode: Temperature < -150C
      Cryogenic_Mode --> Operating: Temperature > -100C
      Cryogenic_Mode: Fused Silica Optics
      Cryogenic_Mode: Invar 36 Housing
      Operating: Standard Glass/Plastic
  

1.3. Cross-Domain Application: Aerospace

• Enabling Description: The microscope objective design is adapted for real-time monitoring of microbial contamination in spacecraft water recycling systems. The flow cell (cuvette 603) is integrated into a bypass line of the water system. The objective's high numerical aperture and aberration correction are critical for detecting and identifying single-celled organisms or biofilms at low concentrations. The entire assembly is ruggedized to withstand launch vibrations (up to 20 Grms) and space radiation, using rad-hardened glass for the optical elements and a titanium housing.

  flowchart LR
      subgraph Spacecraft Water System
          A[Main Water Line] --> B{Bypass Valve};
          B --> C[Micro-Flow Cell];
          C --> D[Return to System];
      end
      subgraph Contaminant Detection Module
          E(Laser Diode) --> C;
          C -- Light --> F(Composite Objective);
          F -- Signal --> G(WDM & Detector);
          G -- Data --> H(Onboard Computer);
      end
  

1.4. Cross-Domain Application: AgTech (Agricultural Technology)

• Enabling Description: The objective is integrated into a portable soil analysis device for in-field quantification of microbial populations and spore viability. A microfluidic chip replaces the cuvette, into which a soil suspension is injected. The objective's large field of view allows for simultaneous imaging of multiple microfluidic channels. Illumination is provided by a battery-powered LED array, and the collected fluorescence data is processed by an embedded system to provide farmers with immediate feedback on soil health and pathogen load.

  sequenceDiagram
      participant Farmer
      participant Device
      participant SoilSample
      participant Cloud
      Farmer->>Device: Inject Soil Suspension
      Device->>SoilSample: Illuminate with LED
      SoilSample-->>Device: Emit Fluorescence
      Device->>Device: Image via Composite Objective
      Device->>Cloud: Transmit Processed Data
      Cloud-->>Farmer: Display Soil Health Report
  

1.5. Integration with Emerging Tech: AI-Driven Adaptive Optics

• Enabling Description: The aberration corrector plate is replaced with a deformable mirror (DM) controlled by an artificial intelligence algorithm. A wavefront sensor is placed at the image plane to detect residual aberrations in real-time. The AI, a trained convolutional neural network (CNN), analyzes the sensor data and continuously adjusts the DM's surface profile to correct for thermal drift, minor misalignments, or variations in the refractive index of the sample fluid. This creates an adaptive optical system that maintains diffraction-limited performance under changing operating conditions. An IoT sensor on the objective housing monitors temperature and vibration, feeding this data to the AI as additional input for predictive aberration correction.

  graph TD
      A[Light from Concave Mirror] --> B(Deformable Mirror);
      B --> C[Image Plane];
      C --> D{Wavefront Sensor};
      D -- Aberration Data --> E(AI Control Unit);
      F{IoT Temp/Vibration Sensor} -- Environmental Data --> E;
      E -- Control Signals --> B;
  

1.6. The "Inverse" or Failure Mode: Fail-Safe Athermal Design

• Enabling Description: The objective is designed for low-power, field-deployable applications where reliability is paramount. It employs a passive athermal design. The housing is made of a material with a coefficient of thermal expansion that precisely matches the thermo-optic coefficient (dn/dT) of the primary optical elements (e.g., a PMMA lens with an aluminum housing). This ensures that as temperature changes, the expansion or contraction of the housing adjusts the spacing between the mirror and corrector plate to maintain focus without any active electronic intervention. In case of severe shock causing misalignment, the components are kinematically mounted to return to a pre-defined, slightly defocused "safe mode" that still allows for basic particle counting, albeit with reduced resolution, preventing total system failure.

  stateDiagram-v2
      state "Optimal Focus" as Optimal
      state "Athermal Drift" as Drift
      state "Fail-Safe Defocus" as Failsafe
  
      [*] --> Optimal
      Optimal --> Drift: Temperature Change
      Drift --> Optimal: Passive Compensation
      Optimal --> Failsafe: High-G Shock Event
      Failsafe --> [*]: Requires Reset
  

---

Disclosure Area 2: Pulsation-Free Fluidic Subsystem

The core concept involves a fluidic system using a T-coupling bypass and an air-trapping filter to dampen pulsations from a pump.

2.1. Material & Component Substitution

• Enabling Description: The T-coupling and conduits are fabricated from perfluoroalkoxy alkanes (PFA) for extreme chemical inertness, allowing the use of aggressive solvents for system cleaning or sample preparation. The particle filter, which doubles as a fluidic capacitor, uses a hydrophilic PVDF membrane with a precisely engineered pore structure to control the volume of trapped air. The reservoir capsule is replaced with a bank of parallel, flexible silicone micro-tubes, which act as distributed, low-volume fluidic capacitors, providing more effective high-frequency pulsation damping.

  graph TD
      A[Liquid Pump (PFA Diaphragm)] --> B{T-Coupling (PFA)};
      B --> C[Bypass to Reservoir];
      B --> D(Silicone Micro-tube Capacitor Bank);
      D --> E{Particle Filter (Hydrophilic PVDF)};
      E --> F[Flow Cell];
      subgraph Air Trap
          G[Trapped Air Bubble]
      end
      E --- G;
  

2.2. Cross-Domain Application: Consumer Electronics (Inkjet Printing)

• Enabling Description: The pulsation-damping principle is applied to high-resolution, multi-material 3D inkjet printing. A high-throughput peristaltic pump supplies ink to a manifold (equivalent to the T-coupling). A bypass line returns excess ink to the reservoir, while the primary line feeds the printhead. Before the printhead, a micro-machined filter with a gas-trapping chamber is installed. This ensures that the ink pressure at the nozzle plate is exceptionally stable, eliminating pressure fluctuations that cause inconsistent droplet volume and placement errors ("banding") in the printed object.

  sequenceDiagram
      participant Pump
      participant Manifold
      participant Ink_Reservoir
      participant Filter_Capacitor
      participant Printhead
      Pump->>Manifold: Pulsating Ink Flow
      Manifold->>Ink_Reservoir: Divert excess ink (Bypass)
      Manifold->>Filter_Capacitor: Forward main flow
      Filter_Capacitor->>Printhead: Deliver Stable-Pressure Ink
      Printhead->>: Print Layer
  

2.3. Integration with Emerging Tech: IoT-Monitored Smart Fluidics

• Enabling Description: The fluidic system is equipped with MEMS-based pressure sensors before and after the T-coupling, and at the inlet of the flow cell. These IoT-enabled sensors stream real-time pressure data to a central controller. The controller uses a machine learning model to detect anomalies in the pressure differential, which can indicate a clog in the particle filter, a leak in the bypass line, or degradation of the pump tubing. The system can then auto-adjust the pump speed to compensate or trigger a maintenance alert. The blockchain is used to log every maintenance event and component replacement, creating an immutable service record for regulatory compliance (e.g., in clinical diagnostics).

  flowchart LR
      Pump --> T_Coupling;
      T_Coupling --> Bypass;
      T_Coupling --> Main_Line;
      Main_Line --> Filter;
      Filter --> Flow_Cell;
  
      subgraph IoT Monitoring
          Sensor1[Pressure Sensor] --> T_Coupling;
          Sensor2[Pressure Sensor] --> Main_Line;
          Sensor3[Pressure Sensor] --> Flow_Cell;
          Controller(AI Controller) -- adjusts --> Pump;
          Sensor1 -- data --> Controller;
          Sensor2 -- data --> Controller;
          Sensor3 -- data --> Controller;
          Controller -- log event --> Blockchain;
      end
  

2.4. The "Inverse" or Failure Mode: Controlled Pulsation Mode for Micro-mixing

• Enabling Description: The system is designed to operate in an alternative "pulsation-on" mode for applications requiring in-line mixing of a sample with a reagent. The bypass line is closed via a solenoid valve, and the air-trapping filter is replaced with a solid-state damper that has minimal capacitance. The pump controller is programmed to introduce specific, high-frequency pressure oscillations (e.g., 100-500 Hz). These controlled pulses induce chaotic advection within the flow channel immediately prior to the viewing zone, ensuring rapid and complete mixing of the sample and sheath fluid (now containing a reagent) without the need for a separate mechanical mixer. This mode is useful for kinetic studies of cellular reactions.

  stateDiagram-v2
      state "Stable Flow Mode" as Stable {
          direction LR
          Bypass_Valve: OPEN
          Filter: Air-Trap Engaged
      }
      state "Pulsatile Mixing Mode" as Mixing {
          direction LR
          Bypass_Valve: CLOSED
          Filter: Solid-State Damper
          Pump: Frequency-Modulated
      }
      [*] --> Stable
      Stable --> Mixing: Activate Reagent Mixing
      Mixing --> Stable: End Kinetic Analysis
  

---

Disclosure Area 3: Wavelength Division Multiplexer (WDM)

The core concept is a WDM with a cascaded image relay architecture to create a long, collimated beam path for inserting dichroic filters.

3.1. Component Substitution & Miniaturization

• Enabling Description: The entire WDM assembly is miniaturized onto a silicon photonics chip. The "extended light source" is the output of a multi-mode optical fiber pigtailed to the chip. The collimating and relay optical elements are replaced with integrated graded-index (GRIN) lenses fabricated directly into the silicon substrate. The dichroic filters are replaced by thin-film interference filters deposited in sequence along a trench etched into the silicon. The light is guided by silicon nitride waveguides from the filters to on-chip avalanche photodiodes (APDs). This creates a monolithic, alignment-free WDM that is orders of magnitude smaller and more robust.

  graph TD
      subgraph Silicon Photonics Chip
          A[Fiber Input] --> B(GRIN Collimator);
          B -- Collimated Beam --> C{Trench with Dichroic Filter 1};
          C -- Transmitted --> D(GRIN Relay Lens);
          C -- Reflected --> E(Waveguide);
          E --> F[On-Chip APD 1];
          D --> G{Dichroic Filter 2};
          G -- Reflected --> H(Waveguide);
          H --> I[On-Chip APD 2];
      end
  

3.2. Cross-Domain Application: Telecommunications

• Enabling Description: The cascaded image relay architecture is adapted for a free-space optical (FSO) communication de-multiplexer. A received broadband laser signal from a telescope is treated as the extended light source. The first optical element collimates this light. The long, collimated path allows for the insertion of highly sensitive, temperature-controlled, narrow-band dichroic filters. Each filter peels off a specific data channel (wavelength) and directs it to a high-speed photodetector. The unit-magnification relay stages prevent beam divergence over the required path length, ensuring that each channel can be focused onto a small-area, low-noise detector, which is critical for maximizing signal-to-noise ratio in long-range FSO links.

  flowchart LR
      A[Telescope Receiver] --> B(Collimating Optics);
      B --> C[Relay Stage 1];
      C -- Path --> D{Dichroic 1 (λ1)};
      D -- Reflected λ1 --> E[Detector 1];
      D -- Transmitted --> F[Relay Stage 2];
      F -- Path --> G{Dichroic 2 (λ2)};
      G -- Reflected λ2 --> H[Detector 2];
      G -- Transmitted --> I[...];
  

3.3. Integration with Emerging Tech: AI-Reconfigurable WDM

• Enabling Description: The static dichroic filters are replaced with dynamically tunable optical filters, such as acousto-optic tunable filters (AOTFs) or liquid crystal-based filters, placed along the collimated beam path. An AI-powered spectrometer constantly analyzes the incoming light spectrum. Based on the specific fluorescent dyes detected in a sample, the AI controller reconfigures the WDM in real-time by programming the center wavelengths of each AOTF. This "smart WDM" automatically optimizes the light separation for the specific assay being run, eliminating the need for manual filter changes and enabling the use of novel or custom fluorophores without hardware modification.

  sequenceDiagram
      participant Spectrometer
      participant AI_Controller
      participant AOTF_Bank
      participant Detectors
  
      Spectrometer->>AI_Controller: Transmit Full Spectrum Data
      AI_Controller->>AI_Controller: Identify Fluorophore Peaks
      AI_Controller->>AOTF_Bank: Send New Wavelength Config
      AOTF_Bank->>Detectors: Route Separated Wavelengths
  

---

Combination Prior Art Scenarios

1. Combination with OPC-UA (Open Platform Communications Unified Architecture): The flow cytometer's control system, including the LD power control, peristaltic pump speed, and fluidic valve states, is integrated using an OPC-UA server. This open standard allows the cytometer (as described in US 12,174,106) to be seamlessly integrated into a larger laboratory automation system. A central scheduler can control the cytometer, a robotic sample handler, and a data analysis server using a standardized communication protocol. This combination would be obvious to one skilled in the art of laboratory automation seeking to create an interoperable diagnostic workflow.

2. Combination with FIJI/ImageJ (Open-Source Image Processing): The digital imaging capabilities of the flow cytometer, which can capture images of individual cells, are combined with the open-source FIJI/ImageJ software platform. The cytometer's output is a stream of TIFF images with associated metadata (FSC, SSC, fluorescence intensity). A custom ImageJ plugin is developed to automate the analysis of these images, performing cell segmentation, morphological feature extraction, and fluorescence colocalization analysis. This leverages a widely used, free platform to enhance the analytical power of the hardware, a step that would be an obvious development for researchers using the instrument.

3. Combination with a Luer-Lok Standard (ISO 80369-7): The fluidic connections to and from the flow cell, sample inlet, and sheath fluid reservoir of the fluidic subsystem in US 12,174,106 are all implemented using standard Luer-Lok connectors. This allows the cytometer to be used with standard, off-the-shelf syringes, tubing sets, and sample preparation devices from any manufacturer. This modification, while simple, makes the system universally compatible and would be an obvious design choice for anyone aiming to commercialize the described fluidic system for use in clinical or research laboratories where such standards are ubiquitous.