ABS Global, Inc. v. Cytonome/ST, LLC

1. Case Identification

• Case #: IPR2017-02162
• Patent #: 9,446,912
• Filed: October 5, 2017
• Petitioner(s): ABS GLOBAL, INC.
• Patent Owner(s): CYTONOME/ST, LLC
• Challenged Claims: 2, 15, 18, and 20-25

2. Patent Overview

• Title: Multilayer Hydrodynamic Sheath Flow Structure
• Brief Description: The ’912 patent discloses microfluidic flow structures for use in applications like flow cytometry. The technology centers on using "hydrodynamic focusing," where a central sample fluid stream containing particles is surrounded and compressed by one or more "sheath fluids" to align the particles into a single file for analysis.

3. Grounds for Unpatentability

Ground 1: Anticipation of Claims 2, 15, and 20-25 - Claims 2, 15, and 20-25 are anticipated under 35 U.S.C. §102 by Wada.

• Prior Art Relied Upon: Wada (Patent 6,506,609).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Wada, which teaches the focusing of microparticles in microfluidic systems, discloses every element of the challenged claims. Specifically, Wada’s figures (e.g., Fig. 22) show a microfluidic device with a primary flow channel for conveying a particle sample. This device includes a first pair of opposing sheath fluid channels that introduce sheath fluid from the sides to focus the sample (meeting the "first sheath fluid channel" and "symmetrical pair" limitations). Wada further describes using a second, downstream set of opposing channels for additional focusing or sorting, which Petitioner asserted meets the limitations for a "second sheath fluid channel" located "downstream" from the first.
  • Key Aspects: Petitioner contended that Wada explicitly teaches fabricating channels on a substrate and describes using inlets for introducing sample and sheath fluids, thereby meeting the structural limitations of independent claims 2 and 15 and their dependents.

Ground 2: Obviousness over Wada and Micronics 2001 - Claims 2, 15, and 20-25 are obvious over Wada in view of Micronics 2001.

• Prior Art Relied Upon: Wada (Patent 6,506,609) and Micronics 2001 (a 2001 journal article by Weigl et al. describing a commercially developed flow cytometer).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground was presented as an alternative to anticipation. Petitioner argued that to the extent Wada is found not to explicitly disclose certain practical elements—such as specific inlet structures, the concept of the sheath fluid physically "suspending" particles, or achieving three-dimensional focusing (i.e., in a "transverse" or "thickness" direction)—these features were well-known and would have been obvious to add. Wada provides the fundamental multi-channel focusing architecture. Micronics 2001, which describes a commercially marketed microfluidic device for cell analysis, explicitly teaches the use of 3D hydrodynamic focusing to create a single-file particle stream and illustrates the routine nature of designing and fabricating such devices.
  • Motivation to Combine: A person of ordinary skill in the art (POSITA) seeking to apply Wada’s focusing system to a practical flow cytometry application would combine its teachings with the established design principles shown in Micronics 2001. Micronics 2001 provided a known, successful template for achieving the precise 3D particle control needed for cell analysis, which is an explicit goal of Wada.
  • Expectation of Success: A POSITA would have a high expectation of success, as Micronics 2001 described the ability to rapidly prototype and test complex 3D microfluidic structures within 24 hours using commercially available software and standard fabrication techniques. This demonstrated that combining such features was a routine and predictable design choice.

Ground 3: Obviousness of Claim 18 over Wada and Nieuwenhuis 2002 - Claim 18 is obvious over Wada in view of Nieuwenhuis 2002.

• Prior Art Relied Upon: Wada (Patent 6,506,609) and Nieuwenhuis 2002 (a 2002 symposium paper on microfluidic systems).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground targeted the specific limitations of claim 18, which depends on claim 15. Claim 18 requires sheath fluid to be introduced (1) at a first region with a flow direction "substantially aligned" with the primary channel's axis and (2) at a second, downstream region with a flow direction "substantially perpendicular" to that axis. Petitioner asserted Wada discloses the perpendicular introduction region (e.g., the side channels in Fig. 22). However, to disclose the aligned introduction region, Petitioner cited Nieuwenhuis 2002. Figure 1 of Nieuwenhuis 2002 explicitly shows a device with an upstream sheath inlet that introduces fluid longitudinally along the primary channel, combined with downstream, perpendicular control inlets for horizontal focusing.
  • Motivation to Combine: A POSITA designing a system based on Wada would have recognized the common design features and objectives shared with Nieuwenhuis 2002, namely the hydrodynamic focusing of particles. To achieve enhanced control, particularly the "vertical control of sample flow dimensions" demonstrated in Nieuwenhuis 2002, it would have been a logical and obvious design choice to incorporate its longitudinally arranged sheath inlet into the Wada system.
  • Expectation of Success: The combination would have been expected to succeed because Nieuwenhuis 2002 demonstrated the operability and utility of this specific inlet configuration for achieving precise, multi-dimensional focusing.

4. Key Claim Construction Positions

• "Suspending" (Preamble, Claims 2, 15): Petitioner argued that "suspending a particle in a sheath fluid" should be construed broadly as "surrounding." This construction relies on the patent’s specification, which describes the sheath fluid enveloping and pinching the sample fluid. Petitioner asserted this term does not require the sheath fluid to physically contact the particles, a distinction relevant to whether prior art that shows narrow fluidic confinement without guaranteed contact meets the limitation.
• "Symmetrically introduced . . . with respect to a centerline" (Claim 21): Petitioner proposed this term be given its plain and ordinary meaning: "introduced on opposite sides of the primary flow channel with respect to a centerline." This construction supports the argument that the opposing channel pairs shown in Wada (e.g., Fig. 22) meet this limitation.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that institution would not be improper under §325(d) because the "same or substantially the same prior art or arguments" were not considered during the original prosecution of the ’912 patent. Although Wada was disclosed in an Information Disclosure Statement, it was never applied in a rejection by the Examiner, and the key prior art references of Micronics 2001 and Nieuwenhuis 2002 were not before the Examiner at all. Petitioner contended the current grounds present a new, more thorough challenge.

6. Relief Requested

• Petitioner requested the institution of an inter partes review (IPR) and the cancellation of claims 2, 15, 18, and 20-25 of the ’912 patent as unpatentable.