PTAB

PGR2025-00084

Cytek Biosciences Inc v. Beckman Coulter Inc

Key Events

Petition

petition

Title: Flow Cytometer
Brief Description: The ’106 patent discloses a flow cytometer that uses a wavelength division multiplexer (WDM) to analyze fluorescent light from particles. The WDM employs a collimating optical element and a zig-zag arrangement of mirrors and dichroic filters to separate the light into distinct color bands for detection by semiconductor detectors.

Prior Art Relied Upon: Chandler (Patent 6,139,800) and Goodman (Patent 6,542,306).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner asserted that Chandler taught an improved flow cytometer that uses filtering, amplification, and digital conversion (FADC) units to demultiplex and detect fluorescent light. Goodman taught a compact, efficient WDM for the analogous field of optical communications, which uses a zig-zag optical path between a row of mirrors and a row of dichroic filters within a solid optical block. The proposed combination replaced Chandler’s suboptimal branched FADC units with Goodman’s more modular and efficient WDM design.
- Motivation to Combine: A POSITA would combine the references to achieve Chandler’s stated goals of a “small and inexpensive” flow cytometer. Petitioner argued that Chandler’s FADC unit footprint was a known problem, and a POSITA would have looked to analogous arts, such as the optical communications industry where Goodman’s compact WDM was a known solution, to miniaturize the system.
- Expectation of Success: Petitioner contended a POSITA would have had a high expectation of success because Goodman’s WDM was designed for easy incorporation into other optical systems. Furthermore, the ’106 patent specification itself acknowledged that WDM techniques from the optical communication industry are “readily adapted for fluorescence light detection” in flow cytometry.

Prior Art Relied Upon: Oostman (Patent 6,683,314), Goodman (Patent 6,542,306), and Frazier (Patent 8,284,402).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued that Oostman taught a flow cytometer using detector array clusters for color separation. The combination substituted Oostman's less-integrated detector arrangement with Goodman's compact, optical-block WDM. Frazier was then incorporated for its teaching of using specific semiconductor detectors, namely avalanche photodiodes (APDs), in a zig-zag WDM configuration similar to Goodman's.
- Motivation to Combine: A POSITA would combine Oostman and Goodman to solve the shared problem of developing a compact, cost-effective WDM, replacing Oostman’s design with Goodman’s more efficient optical block. A POSITA would have further incorporated Frazier’s teachings to use APDs, which were known to be smaller, more sensitive, and highly desirable alternatives to traditional photomultiplier tubes (PMTs), thus further improving the combined system’s footprint and performance.
- Expectation of Success: Success was predictable, as the references all concerned modular optical systems. The benefits of APDs in flow cytometers were well-known, and technical hurdles to their implementation had long been overcome, making their integration into the Oostman-Goodman system a routine design choice.

Prior Art Relied Upon: Not applicable (based on intrinsic evidence).
Core Argument for this Ground:
- Lack of Written Description for "curved mirror": Petitioner argued that all independent claims reciting a "curved mirror" lack written description support in the patent's priority documents. The earlier specifications only disclosed a "concave mirror," which is a specific subset of "curved mirror." Petitioner asserted that the broader term, which would include functionally distinct convex mirrors, was not described, and thus the inventor did not possess the full scope of the claimed invention at the time of the earlier filings. This alleged defect in the priority claim is also the basis for the petition's eligibility for Post-Grant Review (PGR).
- Lack of Enablement for "semiconductor detector": Petitioner contended the claims were not enabled across their full scope because the specification identified "carbon nanotube detectors" as a type of "semiconductor detector." However, Petitioner argued that as of the patent's effective filing date, carbon nanotube detectors were neither commercially available nor described in the patent in sufficient detail to allow a POSITA to make and use one without undue experimentation.

"collecting optical element" / "collimating optical element": Petitioner noted these terms are subject to means-plus-function interpretation. For the purposes of the petition, Petitioner adopted the Patent Owner's proposed constructions from related litigation to demonstrate that the claims are unpatentable even under the Patent Owner's own interpretations.
"curved mirror": Petitioner argued this term is broader than "concave mirror" and that the specification's sole disclosure of a concave mirror cannot provide written description support for the broader genus of all curved mirrors (including convex).

Petitioner requested institution of a Post-Grant Review and cancellation of claims 1, 2, 10, 11, 13, 14, and 17 of the '106 patent as unpatentable.