PTAB

IPR2018-01717

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 a continuous glucose monitor (CGM). The technology is directed to employing sensor electronics to apply voltage to an electrochemical glucose sensor, measure the signal response, and evaluate the severity of any erroneous signal to decide whether to accept or discard a glucose measurement.

3. Grounds for Unpatentability

Ground 1: Claims 14-61 are obvious over Berner

  • Prior Art Relied Upon: Berner (Patent 6,233,471).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Berner, which discloses a method for continuously measuring blood glucose using a GlucoWatch™-type biosensor, teaches all limitations of independent claim 14. Berner’s system was described as an electrochemical sensor with multiple electrodes and an enzyme-containing hydrogel film. Petitioner contended Berner's disclosure of a microprocessor with stored program sequences for controlling the device met the "sensor electronics" limitation. The claimed steps of applying a voltage (by switching/cycling), measuring a signal response, detecting an erroneous signal, determining its severity, and discarding the measurement were allegedly taught by Berner’s "data screening" process. This process involved detecting "poor or incorrect signals" (e.g., deviations from expected behavior or excessive background current), quantifying the error (e.g., a "background stability check" or "peak stability" check), and discarding measurements if a predetermined threshold (e.g., 15% difference) was exceeded. Petitioner asserted that Berner's discussion of temperature affecting the "baseline background" signal taught the association of an erroneous signal with a physical condition. The arguments for other independent claims (20, 26, 32, 38, 44, 50, 56) followed the same logic, mapping Berner’s disclosures of various error sources (e.g., electrode surface fouling, temperature changes, pressure, oxygen deficit) to the specific condition recited in each of those claims.
    • Motivation to Combine (for §103 grounds): Not applicable (single reference ground).
    • Expectation of Success (for §103 grounds): Not applicable (single reference ground).

Ground 2: Claims 62-69 are obvious over Berner in view of Schulman

  • Prior Art Relied Upon: Berner (Patent 6,233,471) and Schulman (Patent 5,497,772).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addressed claims 62-69, which added user interface limitations to the system. Petitioner argued that while Berner taught the core glucose sensing system with error detection (as detailed in Ground 1), it only generally disclosed a basic display. Schulman, which is directed to a continuous glucose monitoring system with an advanced user interface, was argued to supply the missing elements. Specifically, Schulman disclosed a monitor with multiple display modes: a "graphic display mode" showing trend graphs over user-selectable time periods (e.g., 3 to 72 hours) and a "monitor mode" showing the current glucose value as large numerals. Petitioner asserted this taught the claimed first, second, and third screens (trend graph over a first period, trend graph over a second different period, and a numerical value). Schulman's disclosure of menu buttons to switch between these modes was argued to teach the ability to "toggle" between screens. Schulman also explicitly taught generating alerts for hypoglycemic or hyperglycemic conditions. The core limitation of generating a value for display only when the error severity is below a threshold was allegedly met by Berner’s disclosure of converting a raw signal to a value only after it passed the data screening process.
    • Motivation to Combine (for §103 grounds): A person of ordinary skill in the art (POSITA) would combine Schulman's user interface teachings with Berner's sensor to improve its capabilities. Since both references address electrochemical glucose monitoring, a POSITA would have recognized the benefit of Schulman's advanced trend graphs and multi-screen display for a continuous monitoring system like Berner's. The user interface was presented as a modular component that could be readily integrated or substituted without changing the underlying sensor technology.
    • Expectation of Success (for §103 grounds): A POSITA would have a high expectation of success. The combination involved integrating known display functionalities with a known sensor type, both from the same technical field. Petitioner argued that implementing Schulman's display features would only require well-understood software modifications (reprogramming Berner's microprocessor) and presented no significant technical obstacles.

4. Key Claim Construction Positions

  • Petitioner argued for constructions based on their plain and ordinary meaning, referencing definitions agreed to or construed in a related ITC proceeding for context. Key terms included:
    • erroneous signal: Construed as a "signal that is not indicative of the glucose level." This broad construction was important for arguing that various signals described in Berner, such as uncorrected background currents or noisy signals, met the limitation.
    • switching, cycling, and pulsing a voltage: Construed as "changing a voltage, periodically repeating a voltage, and abruptly changing a voltage for a brief interval." This construction allowed Petitioner to map Berner's description of alternating polarities and switching between different electrode pairs to the claimed methods of applying voltage.
    • generate an estimated glucose concentration value when the severity...is evaluated to be under a predetermined threshold: This term was central to Ground 2. Petitioner mapped this to Berner's process of first screening data and only then converting the "good" data into a glucose value, combined with Schulman's display features.

5. Relief Requested

  • Petitioner requested the institution of an inter partes review (IPR) for claims 14-69 of the ’460 patent and the cancellation of those claims as unpatentable under 35 U.S.C. §103.