PTAB

IPR2020-00714

Axonics Modulation Technologies Inc v. Medtronic Inc

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Inductively Rechargeable External Energy Source, Charger, System and Method for a Transcutaneous Inductive Charger for an Implantable Medical Device
  • Brief Description: The ’324 patent discloses a system for transferring energy from an external power source to an implantable medical device (IMD). The system features an external device with a temperature sensor and a control circuit that monitors the temperature on the patient-contacting surface and regulates the energy transfer to prevent tissue overheating during recharging.

3. Grounds for Unpatentability

Ground 1: Obviousness over Torgerson and UL 544 - Claims 1, 2, 4, 9, 11-12, 14-15, 18-20 are obvious over Torgerson in view of UL 544.

  • Prior Art Relied Upon: Torgerson (WO 01/83029) and UL 544 (a 1998 industry safety standard).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Torgerson disclosed a complete transcutaneous charging system for an IMD, including a control circuit that regulates charging based on temperature. However, Torgerson’s temperature sensor was located within the IMD to measure internal temperature. UL 544 was an industry safety standard that mandated maximum temperature limits (e.g., 41°C) for any part of a medical device that contacts a patient. UL 544 further taught using a thermocouple in good thermal contact with the external surface to ensure compliance.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would have been compelled to combine these references because compliance with safety standards like UL 544 was mandatory for gaining regulatory approval (e.g., from the FDA) to market a medical device. Therefore, a POSITA would modify Torgerson’s external charger to include an external temperature sensor and control logic to ensure its patient-contacting surface did not exceed the limits prescribed by UL 544.
    • Expectation of Success: A POSITA would have a high expectation of success, as Torgerson already taught a temperature-based feedback control system. Applying this known control strategy to a different, but necessary, temperature input (from an external sensor as suggested by UL 544) was a predictable modification to ensure patient safety.

Ground 2: Obviousness over Torgerson, UL 544, and Wang - Claims 3, 6-8, 13, 16-17, and 21-24 are obvious over Torgerson in view of UL 544 further in view of Wang.

  • Prior Art Relied Upon: Torgerson (WO 01/83029), UL 544 (a 1998 industry safety standard), and Wang (Patent 5,702,431).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon the combination of Torgerson and UL 544. Petitioner asserted that the additional claims recited specific, well-known methods for controlling energy transfer to limit temperature, such as controlling the duty cycle (claim 3), limiting the time of energy transfer (claim 6), switching the energy transfer on and off (claim 7), and limiting the driving current (claim 8). Wang was cited as teaching these exact techniques for the same purpose: reducing peak temperature rise during transcutaneous charging by using a pulse width modulation (PWM) controller to adjust the duty cycle or by implementing a current-step protocol.
    • Motivation to Combine: A POSITA, having already been motivated to implement temperature control per Torgerson and UL 544, would be further motivated to incorporate the specific energy regulation techniques from Wang. Wang addressed the identical problem of mitigating temperature rise and provided established solutions. A POSITA would have recognized Wang’s methods as common and effective ways to implement the temperature control required by the primary combination.
    • Expectation of Success: The combination was a predictable implementation of known solutions (duty cycle/current control from Wang) to solve a known problem (temperature management from Torgerson/UL 544), leading to a high expectation of success.

Ground 3: Obviousness over Barreras and Taylor - Claims 1, 2, 4, 9, 11-12, 14-15, 18-20 are obvious over Barreras in view of Taylor.

  • Prior Art Relied Upon: Barreras (Patent 5,733,313) and Taylor (Patent 6,685,638).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner presented this as an alternative to the Torgerson-based grounds. Barreras was argued to teach a transcutaneous charging system that used a temperature sensor inside the IMD to regulate RF energy transfer and restrict temperature rise. However, like Torgerson, Barreras did not explicitly disclose a temperature sensor on the external housing. Taylor was argued to cure this deficiency by teaching an external transmitter with a housing that rests on the patient and explicitly incorporating a thermistor on the patient-contacting parts (feet) of that housing to ensure the temperature does not exceed safety limits.
    • Motivation to Combine: A POSITA would combine Barreras and Taylor to ensure patient safety and obtain regulatory approval. Since Barreras taught an external device worn by the patient, a POSITA would have found it obvious to incorporate the housing and external temperature sensor taught by Taylor to monitor the patient-contacting surface, a critical safety feature.
    • Expectation of Success: Combining Taylor’s external sensor with Barreras’s existing temperature-based control circuitry was a simple substitution of one temperature input for another to achieve the predictable result of a safer, compliant device.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including combinations incorporating Wang to add specific power control methods to the Barreras/Taylor system, and combinations incorporating Mann (Patent 4,082,097) to add features like user status indicators and adjustable assemblies.

4. Key Claim Construction Positions

  • "[a temperature sensor adapted to provide an output] indicative of a temperature of the side of the housing": Petitioner argued this term should be construed as "accurately measuring a temperature of the external surface portion of housing that is placed against the patient during recharging." This construction was based on the specification's emphasis that the sensor's purpose is to prevent heating patient tissue to deleterious levels, which necessitates an accurate measurement at the point of contact.
  • "Adjustable assembly adapted to adjust efficiency of energy transfer...": Petitioner proposed this term be construed as "a component of the external device that is moveable relative to another component of the external device to adjust efficiency of charging." This was based on the specification's disclosure of a moveable magnetic core used to "fine tune" the alignment between the external and internal coils.

5. Relief Requested

  • Petitioner requests the institution of an inter partes review and cancellation of claims 1-24 of the ’324 patent as unpatentable.