The parties and the court
The case is Cytek Biosciences, Inc. v. Beckman Coulter, Inc., No. 1:26-cv-01342 (D. Del.), filed October 16, 2026. The complaint says Cytek is a Delaware corporation with its principal place of business in Fremont, California, and that it owns all right, title, and interest in the four asserted patents. It alleges, on information and belief, that Beckman Coulter is a Delaware corporation with its principal place of business in Brea, California. Subject matter jurisdiction is pleaded under 28 U.S.C. 1331 and 1338(a), and venue under 28 U.S.C. 1400(b) because Beckman Coulter is a Delaware corporation. The only defendant is Beckman Coulter, Inc. The Commission's receipt notice for the ITC complaint lists a second proposed respondent, Beckman Coulter Biotechnology (Suzhou) Co., Ltd., which is not named in Delaware.
The civil cover sheet lists Beckman Coulter, Inc. v. Cytek Biosciences, Inc., No. 1:24-cv-00945 (D. Del.), before Judge Colm F. Connolly, as a related case, and the complaint says that case is pending before the same court. The docket shows a case assignment entry and an entry for standing orders marked CFC, both on October 21, 2026. A proof of service filed October 20, 2026 says the summons and complaint were served on Beckman Coulter's registered agent that day. The complaint is signed by Morris, Nichols, Arsht & Tunnell LLP, and Cytek's Rule 7.1 statement filed the same day also lists Cooley LLP of counsel. Cytek demands a jury.
Overlap with the ITC complaint
Paragraph 3 of the complaint says Cytek "also brought suit against Beckman Coulter in the United States International Trade Commission on October 8, 2026, asserting some of the same patents at issue here (the '128 patent, the '167 patent, and the '245 patent)." That paragraph does not list the '868 patent. The Commission's receipt notice for the ITC complaint, DN 3943, published October 14, 2026 at 91 Fed. Reg. 65257, does not list patent numbers, so the overlap comes from the Delaware complaint. Beyond that paragraph, the complaint does not discuss the ITC proceeding, and it does not mention a stay or 28 U.S.C. 1659.
Section 1659(a) provides that, in a civil action involving parties that are also parties to a section 337 proceeding, the district court shall stay, at the request of a party that is also a respondent in the Commission proceeding, proceedings in the civil action with respect to any claim that involves the same issues, until the Commission's determination becomes final. The request must be made within 30 days after the party is named as a respondent in the Commission proceeding, or 30 days after the district court action is filed, whichever is later.
The four patents
U.S. Patent 10,739,245, titled Compact Multi-Color Flow Cytometer, was filed April 26, 2017 and issued August 11, 2020. U.S. Patent 11,913,868, titled Compact Detection Module for Flow Cytometers, was filed May 10, 2021 and issued February 27, 2024. U.S. Patent 12,487,167, titled Methods and Apparatus for Full Spectrum Flow Cytometer, was filed June 26, 2021 and issued December 2, 2025. U.S. Patent 12,754,128, titled Methods for Compact Multi-Color Flow Cytometers Having Compact Detection Modules, was filed July 14, 2021 and issued October 6, 2026, ten days before the complaint. The complaint says the '128 and '245 patents are in the same family and both claim priority to U.S. Provisional Application 62/327,946. Google Patents lists the '245 patent with an adjusted expiration of June 9, 2038, the '868 patent with an adjusted expiration of February 28, 2038, and the '167 patent with an anticipated expiration of June 26, 2041. The patents are Exhibits 1 to 4 to the complaint; the exhibits, including the claim charts and evidence exhibits, are not on the public docket.
The claims quoted in the complaint
Each count quotes one claim. Claim 1 of the '128 patent, as quoted, covers a flow cytometer system with a laser system having a plurality of different lasers; a flow cell assembly where fluoresced cells in a fluidics stream scatter the laser beams and emit fluorescent light; at least one optical fiber that collects the fluorescent light at a first end and directs it toward a second end; and at least one light detection module that receives the light from the fiber. The module includes a first optical array with a transparent block, a row of reflection surfaces coupled to one side of the block, and a row of optical filters coupled to the opposite side, plus a first detector chain of N detector channels in a row adjacent the array, where N is eight or more and each channel includes a focusing lens and a photodiode.
Claim 1 of the '167 patent covers a system for analyzing biological fluids. It requires a full spectrum flow cytometer with five or more lasers, each emitting a different wavelength, and four or more detector modules providing N individual photo detectors to capture a full spectrum of visible light, where N is 48 or more and each detector is a photodiode; a single labeled biological sample with over 30 different markers labeled with over 30 and fewer than N different fluorochrome-conjugated antibodies, generating over 30 and fewer than N different colors when excited by the lasers; and a computer system with a display device, a storage device, and a processor, in which the storage device stores data samples from running the sample, the processor generates full spectrum signatures of the fluorescence from the marked cells in a single run, each signature is used to determine the type and quantity of the cells in the sample, and the display device displays the signatures to a user.
Claim 3 of the '868 patent depends from claim 2, which depends from claim 1, and the complaint quotes it in independent form. It covers an apparatus with two light detection modules, each demultiplexing fluorescent light in its own range of wavelengths. Each module has a row of detectors, a transparent block adjacent to them, micro-mirrors coupled to one side of the block, and a row of filters coupled to the opposite side, each filter reflecting light to a micro-mirror and passing light of a different wavelength range toward a detector. An input channel receives a fluorescent light beam and splits it into the two wavelength ranges for the two modules.
Claim 21 of the '245 patent depends from claim 20, which depends from claim 1, and is also quoted in independent form. It covers a flow cytometry system with a laser system, a flow cell assembly, a fiber assembly that collects the fluorescent light, and a receiver assembly that includes a photodiode detector array of avalanche photodiodes with at least sixteen channels, trans-impedance amplifier circuits that convert the array's input current into an output voltage signal for each channel, and analog-to-digital converters, with each trans-impedance amplifier circuit coupled to a different converter.
Accused products and theories
The complaint accuses the mosaic 88 and mosaic 63 flow cytometry detector module systems, which it says Beckman Coulter first launched in March 2025, and related products, including the CytoFLEX S and CytoFLEX LX flow cytometry systems when combined with the mosaic modules. It alleges the mosaic products are optical detection systems connected by fiber optic connections to Beckman Coulter's conventional CytoFLEX cytometers, and that the combined systems use up to six lasers and up to 81 fluorescence detectors. Paragraph 29 says the exemplary charts cover at least claims 1, 11, 15 to 21, and 23 to 29 of the '128 patent (Exhibits 5 and 6), claims 1 to 4, 6, and 8 to 20 of the '167 patent (Exhibit 7), claim 3 of the '868 patent (Exhibit 8), and claim 21 of the '245 patent (Exhibits 9 and 10).
Each count alleges, on information and belief, infringement directly and indirectly, literally or under the doctrine of equivalents, including through use in research and development and product testing. Each count also alleges induced infringement under 35 U.S.C. 271(b) through marketing materials, data sheets, user manuals, trade shows, and sales and distribution channels. Contributory infringement is pleaded, on information and belief, on the '128, '868, and '245 patents, on the theory that the quoted claims are infringed when a mosaic product is combined with a CytoFLEX cytometer and that the mosaic products are especially made or adapted for that use. The '167 count does not plead contributory infringement.
Copying, notice, and willfulness allegations
The complaint alleges that Beckman Coulter copied Cytek's Aurora system. It alleges that Beckman Coulter held an initial meeting for an internal project called Rainbow in December 2019 to develop its own spectral flow cytometer, bought an Aurora in September 2020, and received it in October 2020, and that its internal documents from December 2020 show steps to benchmark against the Aurora and to reverse-engineer the Aurora's unmixing algorithm and detector channel bin widths. For those points it cites trial transcript excerpts and trial exhibits attached as Exhibits 38 to 41, and it reproduces annotated document excerpts. It alleges, on information and belief, that Beckman Coulter used the information gleaned from that work in developing the mosaic products.
On notice, the complaint alleges that Cytek notified Beckman Coulter of each of the four patents and its alleged infringement by letter dated October 6, 2026 (Exhibit 36), the day the '128 patent issued. It also alleges, on information and belief, that Beckman Coulter regards Cytek as a competitor and has long monitored Cytek's patent activities, and it points to specific records: Beckman Coulter's first amended complaint in the 2024 case, which it says cites the '245 patent; an expert report for Beckman Coulter in that case, which it says cited, no later than December 19, 2025, Cytek's online patent marking page listing the applications that became the '128 and '167 patents, and cited the '868 patent; a January 31, 2025 international search report on a Beckman Coulter PCT application that it says identifies the published application that became the '167 patent; and a Beckman Coulter U.S. application that it says cites the published application corresponding to the '868 patent. The complaint says Cytek has marked its full spectrum products with at least the '245 and '868 patents, through product labeling and a virtual marking page, since at least October 31, 2025. Willfulness is pleaded on all four patents, on information and belief, and the complaint says the alleged copying further shows willfulness.
Relief requested
Cytek asks for a judgment of infringement; preliminary and permanent injunctions against making, using, offering for sale, selling, or importing the accused products and any other product that infringes or induces or contributes to infringement of the asserted patents, until the last of them expires; damages under 35 U.S.C. 284, including lost profits or, at a minimum, a reasonable royalty, with pre-judgment and post-judgment interest; a finding of willfulness and enhanced damages up to three times; costs and expenses; and an exceptional-case finding and attorney fees under 35 U.S.C. 285. Each count alleges irreparable harm on the ground that the companies are direct competitors in flow cytometry. Cytek demands a jury under Federal Rule of Civil Procedure 38(b).
Two forums and a pending 2024 case
The Delaware complaint runs alongside Cytek's ITC complaint and Beckman Coulter's own patent suit against Cytek, No. 1:24-cv-00945, which the complaint says is pending before the same court. Compared with the ITC complaint as described in the receipt notice and in paragraph 3, the Delaware complaint includes the '868 patent, which paragraph 3 does not list among the patents asserted at the ITC, and names only Beckman Coulter, Inc. as a defendant. It seeks damages, including lost profits, and enhanced damages, alongside preliminary and permanent injunctions. The '128 patent issued on October 6, 2026, the same date as the notice letter, so the complaint's pre-suit knowledge allegations for that patent rest on the letter and on the alleged monitoring of its application.
What to watch next
Watch for Beckman Coulter's answer or a Rule 12 motion. Watch also for any request by Beckman Coulter under 28 U.S.C. 1659 to stay claims that involve the same issues as the Commission proceeding, for a preliminary injunction motion, for any motion to coordinate the case with No. 1:24-cv-00945, and for inter partes review petitions on the asserted patents. The case can end at any time, including by settlement or voluntary dismissal.