Fitbit Inc v. Valencell Inc

1. Case Identification

• Case #: IPR2017-01556
• Patent #: 8,923,941
• Filed: June 9, 2017
• Petitioner(s): Fitbit, Inc.
• Patent Owner(s): Valencell, Inc.
• Challenged Claims: 14-21

2. Patent Overview

• Title: Wearable Physiological Monitoring Device
• Brief Description: The ’941 patent discloses a wearable monitoring device, such as an earbud or headset, that uses photoplethysmography (PPG) to measure physiological information. The device integrates a PPG sensor and a motion sensor into a chipset to detect biometric data and process signals to reduce motion artifacts.

3. Grounds for Unpatentability

Ground 1: Obviousness over Wrist-Worn References - Claims 14, 15, and 21 are obvious over Kosuda in view of Maekawa.

• Prior Art Relied Upon: Kosuda (Application # 2004/0186387) and Maekawa (Japanese Application Publication No. 2005-270544).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Kosuda, a wrist-worn pulse measurement device, disclosed every element of independent claim 14 except for a “non-air light transmissive material” between the PPG sensor and its window. Kosuda taught a wearable device with a housing, a chipset containing a PPG sensor, a motion sensor (accelerometer), and a signal processor configured to use the motion sensor data to reduce motion artifacts in the PPG signal. Petitioner asserted that Kosuda’s transparent glass cover qualified as the claimed “window.”
  • Motivation to Combine: Petitioner contended that PPG sensors were well known to be susceptible to light noise (e.g., surface light that does not penetrate tissue) which degrades the signal-to-noise ratio. Maekawa taught a solution to this exact problem in a similar wrist-worn device by placing a non-air light transmissive material (a bundle of optical fibers) between the sensor and the window to block surface light. A POSITA would combine Maekawa’s technique with Kosuda’s device to achieve the predictable result of improved signal quality.
  • Expectation of Success: A POSITA would have a high expectation of success, as the combination involved applying a known technique from a similar device (Maekawa) to solve a known problem (light noise) in Kosuda’s device.

Ground 2: Obviousness over Ear-Worn References - Claims 14-19 and 21 are obvious over Aceti in view of Fricke.

• Prior Art Relied Upon: Aceti (Application # 2005/0059870) and Fricke (Application # 2009/0105556).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner argued that Aceti, an ear-worn animal monitoring device, disclosed a wearable device with a housing, PPG sensor, motion sensor, a window (optically transparent elastomer), and a non-air light transmissive material (fiber optic cables) as required by claim 14. However, Aceti did not explicitly disclose that its processor was configured to reduce motion artifacts. Fricke, another ear-worn physiological monitor, explicitly taught configuring a signal processor to use data from an accelerometer to remove motion artifacts from a PPG signal, thereby improving accuracy.
  • Motivation to Combine: Motion artifacts were a well-known problem in wearable PPG sensors, and noise cancellation techniques were commonly used to address them. Petitioner argued a POSITA would have been motivated to incorporate Fricke’s established motion artifact reduction processing into Aceti’s device. This modification would improve the accuracy of Aceti’s device, a predictable and desirable outcome. The combination was particularly strong as both Aceti and Fricke relate to ear-worn PPG sensors.
  • Expectation of Success: A POSITA would have reasonably expected success in implementing Fricke’s signal processing in Aceti’s hardware, as it amounted to the application of a known software solution to a known hardware problem in the same technical field.

• Additional Grounds: Petitioner asserted additional obviousness challenges. One ground argued that claims 18-20 were obvious over Kosuda and Maekawa in view of Han (a 2007 IEEE article), which taught specific signal processing techniques like band-pass filtering and adaptive filtering to remove footstep-related motion artifacts. Another ground argued that claim 20 was obvious over Aceti and Fricke in view of Comtois (a 2007 IEEE article), which taught using adaptive noise cancellation to specifically remove jogging-related motion artifacts from PPG signals.

4. Key Claim Construction Positions

• "housing": Petitioner proposed construing "housing" as "one or more parts that covers, encloses, supports, or protects; casing." This construction supports finding a housing in prior art devices composed of multiple pieces, such as a main body and a conductor portion.
• "chipset": Petitioner proposed construing "chipset" as "a collection of one or more chips or integrated circuits." This construction was used to argue that even if sensors and processors were discrete ICs on a main board, they collectively formed the claimed chipset, which was an obvious implementation choice for miniaturization.
• "window": Petitioner proposed construing "window" as "an aperture or opening; the framework enclosing such an opening or aperture; a transmissive pane within such an opening or aperture." This broad construction allowed Petitioner to identify a "window" in prior art that used transparent glass, elastomers, or other light-transmissive materials.
• "headset": Petitioner argued for a broad construction of "headset" as "any type of device or earpiece that may be attached to or near the ear of a user," which covered the ear-worn devices in Aceti and Fricke.

5. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claims 14-21 of the ’941 patent as unpatentable under 35 U.S.C. §103.