PTAB

IPR2018-01718

AgaMatrix, Inc. v. Dexcom, Inc.

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1. Case Identification

2. Patent Overview

  • Title: Systems and Methods For Replacing Signal Artifacts In A Glucose Sensor Data Stream
  • Brief Description: The ’460 patent discloses systems and methods for processing data from an electrochemical glucose sensor, such as a continuous glucose monitor (CGM). The technology is directed to applying varied voltages to the sensor, measuring the resulting signal response, and evaluating the severity of any erroneous signals to decide whether to accept or discard a glucose measurement.

3. Grounds for Unpatentability

Ground 1: Claims 14-18, 20-24, 26-30, 32-36, 38-42, and 50-54 are obvious over White in view of Beaty.

  • Prior Art Relied Upon: White (Patent 5,243,516) and Beaty (WO 99/32881).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that White teaches the core components of the claimed glucose sensor system, including a test cell with electrodes and an enzyme-containing film for amperometrically measuring glucose in a biological fluid. White’s system detects errors by applying a measurement potential and determining if the resulting current deviates from a predetermined Cottrell current relationship by comparing ratios of successive current measurements to pre-stored constants. Petitioner asserted Beaty improves upon sensors like White’s by teaching the use of AC impedance measurements to detect and correct for specific error sources, such as temperature, hematocrit, and inadequate sample volume. Petitioner contended that Beaty’s application of AC signals at different frequencies (e.g., 1300Hz for sample volume, 2-10KHz for temperature) constitutes the claimed "switching, cycling, and pulsing a voltage." The combination allegedly discloses all elements of independent claim 14: the sensor system (White), applying varied voltages (White/Beaty), measuring the signal response (White/Beaty), detecting an erroneous signal (White/Beaty), associating the error with specific conditions (e.g., available electrode surface area from White; temperature and biochemical species from Beaty), determining the signal’s severity, and discarding the measurement if it falls outside a predetermined threshold.
    • Motivation to Combine: A POSITA would combine the references because Beaty expressly identifies biosensors of the type described in the White patent as devices whose measurement accuracy can be improved by Beaty’s techniques. Beaty provides an explicit motivation to apply its error-correction methods to White’s foundational sensor design.
    • Expectation of Success: Petitioner contended a POSITA would have a high expectation of success. The combination involves applying a known error-correction technique (Beaty) to a known device (White), which would predictably result in a more robust sensor. The required modifications would involve adding standard circuitry and software, not altering the fundamental electrochemical cell, making the integration straightforward.

Ground 2: Claims 62-66 and 68 are obvious over White and Beaty in view of Schulman.

  • Prior Art Relied Upon: White (Patent 5,243,516), Beaty (WO 99/32881), and Schulman (Patent 5,497,772).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground builds on the White and Beaty combination to address the user interface limitations added in independent claims 62, 63-66, and 68. Petitioner argued that Schulman teaches all the recited user interface features necessary to render these claims obvious. Specifically, Schulman discloses a glucose monitor that displays current glucose concentration, trend graphs, and numerical values. Petitioner asserted Schulman's "graphic display mode" with user-selectable time intervals (e.g., 3 hours vs. 72 hours) and its "monitor mode" showing large numerals correspond to the claimed first, second, and third screens. Schulman further teaches that a user can toggle between these modes via menu buttons. Finally, Schulman explicitly discloses generating an alarm signal if glucose levels fall outside of preset high or low limits, meeting the claimed alert function.
    • Motivation to Combine: A POSITA would be motivated to incorporate Schulman’s advanced display and alarm functions into the improved sensor of White and Beaty to enhance its usability and provide more comprehensive data visualization. Petitioner argued that because the user interface is a modular component, integrating Schulman's features into the White/Beaty system would be an obvious way to improve the overall device.
    • Expectation of Success: Success would be highly expected because implementing Schulman’s display functions would require only well-understood software and display unit modifications. These changes are substantially independent of the underlying sensor hardware and error detection logic from White and Beaty, posing no significant technical hurdles.

4. Key Claim Construction Positions

  • The petition referenced constructions from a related ITC proceeding, arguing they represent the broadest reasonable interpretation.
  • "switching, cycling, and pulsing a voltage": The proposed construction was "changing a voltage, periodically repeating a voltage, and abruptly changing a voltage for a brief interval." Petitioner argued this construction is broad enough to encompass both White’s method of switching between DC potentials for sample detection and measurement, and Beaty’s application of AC signals at different frequencies for error analysis.
  • "erroneous signal": The proposed construction was a "signal that is not indicative of the glucose level." This construction is fundamental to the Petitioner’s invalidity arguments, which are entirely based on prior art methods for identifying and handling signals that are unreliable due to various interferences.

5. Arguments Regarding Discretionary Denial

  • The petition argued that its invalidity grounds were not substantially considered during the original prosecution.
  • Petitioner noted that although Schulman was cited in an Information Disclosure Statement (IDS), it was part of a list of over 1,200 references submitted without analysis or explanation, suggesting the Examiner did not meaningfully review it.
  • Petitioner further asserted that the other primary reference, Beaty, was not before the Patent Office at all and was never considered by the Examiner.

6. Relief Requested

  • Petitioner requested the institution of an inter partes review (IPR) and the cancellation of claims 14-18, 20-24, 26-30, 32-36, 38-42, 50-54, 62-66, and 68 of Patent 9,750,460 as unpatentable under 35 U.S.C. §103.