Axonics Modulation Technologies Inc v. Medtronic Inc

1. Case Identification

• Case #: IPR2019-00678
• Patent #: 7,774,069
• Filed: March 16, 2020
• Petitioner(s): Axonics Modulation Technologies, Inc.
• Patent Owner(s): Medtronic, Inc.
• Challenged Claims: 5-9

2. Patent Overview

• Title: System for Charging an Implantable Medical Device
• Brief Description: The ’069 patent relates to a system for transcutaneously charging the battery of an implanted medical device. The system uses an external charging device with a primary inductive coil and an implanted device with a secondary inductive coil and a rechargeable power source. The purported novelty is an alignment indicator that reports the quality of alignment between the coils as a function of the current generated in the internal power source to optimize the charging process.

3. Grounds for Unpatentability

Ground 1: Claims 5 and 8 are unpatentable as anticipated by Schulman.

• Prior Art Relied Upon: Schulman (Patent 3,942,535).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Schulman, issued nearly three decades before the ’069 patent's priority date, discloses every element of claims 5 and 8. Schulman teaches a rechargeable tissue stimulating system with an external power source and an implanted device containing a rechargeable battery (internal power source) and a secondary coil. Schulman's system includes a telemetry circuit that detects the magnitude of the charging current in the implant and reports it to the external charger. The external charger then provides alignment feedback via light-emitting diodes and a buzzer. Critically, Petitioner asserted that Schulman discloses automatically varying the external power output based on this feedback to maintain a predetermined maximum charging current, thus anticipating the final limitation of claim 5 and the "maximum amount of current" limitation of claim 8.
  • Key Aspects: This ground relies on the argument that Schulman’s closed-loop feedback system, which adjusts power based on telemetered charging current from the implant, meets all limitations of the independent claim, including the "automatically varies" feature.

Ground 2: Claims 5 and 8 are unpatentable as anticipated by Fischell.

• Prior Art Relied Upon: Fischell ("A Long-Lived, Reliable, Rechargeable Cardiac Pacemaker," a 1975 publication).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner contended that Fischell, a 1975 article, discloses a rechargeable cardiac pacemaker system that anticipates claims 5 and 8. The system includes an external charger and an implanted pacemaker with a "pick-up coil" (secondary coil) and a rechargeable Ni-Cd cell (internal power source). Fischell describes a telemetry system that senses the charge current in the battery and transmits a proportional signal to the external charger. The external charger provides alignment feedback to the patient (beeping sounds and lights) based on this telemetered signal. Petitioner argued Fischell explicitly teaches a "feedback control system" in the charger that "maintains the battery charge current at the proper 40 mA level," thereby automatically adjusting its power to generate a predetermined current in the implant, anticipating claim 5. This also meets the "maximum amount" limitation of claim 8.

Ground 3: Claims 6, 7, and 9 are obvious over Schulman in view of Baumann.

• Prior Art Relied Upon: Schulman (Patent 3,942,535) and Baumann (Patent 6,227,204).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner argued that Schulman provides the base system as established in Ground 1. For dependent claims 6 and 7, which require the charging current to vary as a function of the battery's voltage, Baumann was asserted to supply this teaching. Baumann discloses a two-phase charging protocol where charging current is reduced (tapered) after the cell voltage reaches a predetermined limit, teaching the claimed current-voltage relationship. For dependent claim 9, which requires the predetermined current to decline as the battery's internal impedance increases over time, Petitioner asserted Baumann explicitly teaches this. Baumann states that its system regulates charging "depending on the internal resistance of the battery" and that "Older cells with increasing internal resistance... acquire less charge."
  • Motivation to Combine: Petitioner argued a person of ordinary skill in the art (POSITA) would combine the references as they both address charging implantable medical devices. A POSITA would be motivated to incorporate Baumann’s more advanced two-phase charging protocol into Schulman’s system to improve charging speed, safety, and reliability.
  • Expectation of Success: A POSITA would have a high expectation of success as the combination involves applying well-understood battery management principles from Baumann to the analogous system in Schulman.

• Additional Grounds: Petitioner asserted an additional obviousness challenge (Ground 4) against claims 6, 7, and 9 based on Fischell in view of Baumann, relying on a similar rationale as Ground 3.

4. Key Claim Construction Positions

• "measuring said current": Petitioner argued this term is central to the invalidity analysis for all challenged claims. Based on prosecution history estoppel, Petitioner contended the term must be construed to mean "measuring the actual current through the internal power source." During prosecution, the Applicant amended the claims to overcome a rejection over the Wang ’693 patent, replacing the broader phrase "a current associated with said internal power source" with the narrower "a current through said internal power source." Petitioner argued this amendment was a clear and unmistakable disavowal of any broader scope, precluding an interpretation that would cover measuring a merely proportional or related value. This narrow construction was argued to be critical for the prior art to meet the claim limitations.

5. Arguments Regarding Discretionary Denial

• Petitioner argued against discretionary denial under §325(d). While Baumann was listed in an Information Disclosure Statement (IDS) during prosecution of the ’069 patent, Petitioner asserted it was never substantively raised, argued, or considered by the Examiner. Furthermore, the primary references of Schulman and Fischell were never before the Examiner, and therefore the combinations presented in the petition are entirely new.

6. Relief Requested

• Petitioner requests institution of an inter partes review (IPR) and cancellation of claims 5-9 of the ’069 patent as unpatentable.