3B Medical Mfg LLC v. Rhythm Healthcare LLC

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: 3B Medical Manufacturing, LLC (Florida)
  • Defendant: Rhythm Healthcare, LLC (Delaware)
  • Plaintiff’s Counsel: Hahn Loeser & Parks LLP; Carlson, Gaskey & Olds, P.C.
• Case Identification: 8:25-cv-02989, M.D. Fla., 10/31/2025
• Venue Allegations: Plaintiff alleges venue is proper because Defendant has a principal place of business in the district and has committed acts giving rise to the claims within the district, including marketing and sales.
• Core Dispute: Plaintiff alleges that Defendant’s portable oxygen concentrators and associated components infringe a patent related to removable adsorbent cartridges used for gas separation.
• Technical Context: The technology concerns portable medical devices that concentrate oxygen from ambient air for patients requiring supplemental oxygen therapy, a market focused on improving patient mobility and quality of life.
• Key Procedural History: Plaintiff 3B Manufacturing asserts it is the exclusive licensee of the patent-in-suit, originally assigned to VBox, Inc., with the right to enforce it against infringers. The complaint also references pre-suit correspondence sent to the Defendant, which forms the basis for allegations of actual notice and willful infringement.

Case Timeline

Date	Event
2005-02-09	’005 Patent Priority Date
2009-10-20	’005 Patent Issue Date
2018-03-16	Plaintiff becomes exclusive licensee of the ’005 Patent
2025-06-25	Plaintiff sends correspondence to Defendant alleging infringement
2025-10-31	Complaint Filing Date

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 7,604,005 - Adsorbent Cartridge for Oxygen Concentrator

• Patent Identification: U.S. Patent No. 7,604,005, Adsorbent Cartridge for Oxygen Concentrator, issued October 20, 2009 (’005 Patent).

The Invention Explained

• Problem Addressed: The patent's background section describes the drawbacks of existing supplemental oxygen systems, such as high-pressure cylinders that have a short duration and require frequent refilling, and liquid oxygen systems that are bulky and suffer from wasteful evaporation. These limitations detract from the ambulatory usefulness required for patients to live normal lives (’005 Patent, col. 2:7-54).
• The Patented Solution: The invention is a removable gas separation cartridge for a wearable oxygen concentrator. This cartridge contains adsorbent material designed to separate oxygen from ambient air using a vacuum swing adsorption (VSA) process, which operates at pressures below one atmosphere (’005 Patent, col. 3:6-12). As depicted in the patent’s figures, the system is designed as a series of connected modules worn by the user, with the adsorbent cartridge being an easily replaceable component (’005 Patent, Fig. 7).
• Technical Importance: This approach aimed to create a personal oxygen system that is small, lightweight, quiet, and does not require refilling from external sources, thereby improving patient mobility and discretion (’005 Patent, col. 2:66-col. 3:4).

Key Claims at a Glance

• The complaint asserts independent claim 10 (’005 Patent, col. 27:4-18; Compl. ¶26).
• The essential elements of claim 10 are:
  • A removable cartridge for a portable oxygen concentrator
  • an outer casing;
  • a plurality of gas separation columns within the outer casing, each gas separation column containing an adsorbent material that preferentially adsorbs nitrogen, a first end, and a second end;
  • a plurality of inlet ports in the outer casing, each inlet port connect[ed] to the first end of one of the columns; and
  • a plurality of outlet ports in the outer casing, each outlet port connected to the second end of one of the columns.
• The complaint does not explicitly reserve the right to assert dependent claims.

III. The Accused Instrumentality

Product Identification

• The accused instrumentalities are Rhythm Healthcare's P2 Portable Oxygen Concentrator and the corresponding "Sieve Beds" used with the concentrator (Compl. ¶12).

Functionality and Market Context

• The complaint alleges that the accused products are portable oxygen concentrators that perform gas separation (Compl. ¶12). The complaint includes a photograph of the P2 Portable Oxygen Concentrator, showing a compact, portable medical device (Compl. p. 4, Exhibit 1). A separate photograph depicts the accused Sieve Bed, a self-contained component with multiple connection ports visible at one end, which is alleged to be the infringing removable cartridge (Compl. p. 4, Exhibit 2).
• The complaint alleges Defendant is in the business of manufacturing and selling these devices, positioning them in the same market for portable oxygen therapy addressed by the patent-in-suit (Compl. ¶12).

IV. Analysis of Infringement Allegations

The complaint references a claim chart in Exhibit 4 purporting to show infringement of claim 10; however, this exhibit was not attached to the publicly filed complaint. The narrative allegations assert that the accused P2 Portable Oxygen Concentrator and/or the P2 Portable Oxygen Concentrator Sieve Beds meet all limitations of at least claim 10 of the ’005 Patent (Compl. ¶¶27, 37). The visual evidence provided in the complaint shows the accused Sieve Bed as a self-contained unit, which Plaintiff will likely argue functions as the claimed "removable cartridge" (Compl. p. 4, Exhibit 2).

• Identified Points of Contention:
  • Scope Questions: The dispute may center on whether the accused "Sieve Bed" falls within the scope of a "removable cartridge" as that term is used in the patent. The construction of this term, including its structural and functional characteristics as described in the specification, could be a key issue.
  • Technical Questions: A central evidentiary question will be whether the accused Sieve Bed contains the internal structure required by claim 10, specifically "a plurality of gas separation columns" where each column is connected between a distinct inlet port and a distinct outlet port. The complaint does not provide direct evidence of the internal configuration of the accused product.

V. Key Claim Terms for Construction

• The Term: "removable cartridge"

• Context and Importance: This term appears in the preamble of claim 10 and defines the overall accused instrumentality. The infringement case depends on demonstrating that the accused Sieve Bed is a "removable cartridge." Practitioners may focus on this term because its scope will determine whether the claim reads on the accused product's architecture.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: The specification describes the invention as including a "removable gas separation cartridge" and depicts it as a user-replaceable module (e.g., cartridge 206) that plugs into the main device (’005 Patent, Abstract; Fig. 7). This could support an interpretation covering any self-contained, user-replaceable component that performs the claimed gas separation function.
  • Evidence for a Narrower Interpretation: The detailed description and figures show specific embodiments of the cartridge with particular structural features and connections (’005 Patent, Fig. 15-16). This may support a narrower construction limited to cartridges with structures corresponding to those specific disclosed embodiments.

• The Term: "a plurality of gas separation columns within the outer casing"

• Context and Importance: This limitation defines the necessary internal structure of the cartridge. Infringement cannot be determined without confirming that the accused Sieve Bed contains multiple, distinct columns. This term is critical because the complaint lacks evidence on the product's internal design.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: The patent claims "a plurality" (meaning two or more) without specifying an exact number or configuration, which could support reading the claim on any design with multiple distinct gas pathways through the adsorbent material (’005 Patent, col. 27:8-9).
  • Evidence for a Narrower Interpretation: The preferred embodiment consistently describes and depicts a three-column arrangement (’005 Patent, Abstract; col. 6:65-67; Fig. 15). This could be used to argue that the term implies a structure similar to the three-column design that is central to the patent's description of operation.

VI. Other Allegations

• Indirect Infringement: The complaint alleges induced infringement under 35 U.S.C. § 271(b). It asserts that Defendant provides instructions and marketing materials that lead its customers to assemble and use the P2 Portable Oxygen Concentrator and Sieve Beds in a manner that directly infringes claim 10 (Compl. ¶¶37, 39). The allegation of knowledge is based on a notice letter sent on June 25, 2025 (Compl. ¶42).
• Willful Infringement: The complaint alleges willful and deliberate infringement. This allegation is based primarily on Defendant's alleged continued infringement after receiving actual notice of the ’005 Patent and the alleged infringement via the June 25, 2025 correspondence (Compl. ¶¶28, 32-33). It further alleges, upon information and belief, that Defendant would have been aware of the patent even prior to this date due to general knowledge of the industry (Compl. ¶29).

VII. Analyst’s Conclusion: Key Questions for the Case

• A central issue will be one of evidentiary proof: What is the actual internal architecture of the accused "Sieve Bed"? The case will depend on discovery revealing whether the product contains a "plurality of gas separation columns" connected to the external ports in the manner required by Claim 10.
• The case will also likely involve a dispute over definitional scope: Can the term "removable cartridge," as defined by the intrinsic evidence of the ’005 Patent, be construed to cover the accused "Sieve Bed" product, or does the accused product’s design present a legally significant structural or functional difference?