PTAB

IPR2016-01679

Dexcom Inc v. AgaMatrix Inc

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Key Events
Petition

1. Case Identification

2. Patent Overview

  • Title: Compound Material Analyte Sensor
  • Brief Description: The ’202 patent is directed to a method of measuring the concentration of an analyte, such as glucose, within an animal body. The method uses an implantable sensor constructed with a structurally flexible core covered by a layer of electrochemically active metal.

3. Grounds for Unpatentability

Ground 1: Obviousness over Wilson and Rosenblatt - Claims 1-3, 5, 6, and 9-11 are obvious over Wilson in view of Rosenblatt.

  • Prior Art Relied Upon: Wilson (a 1992 publication on implantable glucose sensors) and Rosenblatt (Patent 2,719,797).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Wilson disclosed all steps of the claimed method using an implantable, flexible, needle-shaped glucose sensor made from a platinum-iridium wire. However, Wilson’s sensor did not have a plated composite structure. Rosenblatt was cited for its teaching of coating a less expensive, inert metal core, such as tantalum, with a layer of platinum for use in electrochemical applications. Petitioner asserted that substituting Rosenblatt’s cost-effective platinum-coated tantalum electrode for Wilson's solid platinum-iridium wire would result in the sensor structure used in the claimed method—namely, a structurally flexible core (tantalum) covered by an electrochemically active metal layer (platinum).
    • Motivation to Combine: The primary motivation asserted was economic. Wilson's sensor used expensive platinum-iridium wire. Rosenblatt explicitly taught replacing expensive solid platinum electrodes with a cheaper platinum-coated tantalum core to achieve the same desirable electrochemical properties while reducing cost. Petitioner contended a person of ordinary skill in the art (POSITA) would be motivated to apply this well-known cost-saving technique to the sensor in Wilson, as both references relate to the analogous art of electrochemical electrodes.
    • Expectation of Success: Petitioner argued a POSITA would have a high expectation of success because the combination involved the simple substitution of one known electrode material for another to achieve the predictable benefits of lower cost without sacrificing performance.

Ground 2: Anticipation by Hagiwara - Claims 1-3, 6, 8, and 10-11 are anticipated by Hagiwara.

  • Prior Art Relied Upon: Hagiwara (Japanese Application Publication No. S57-110236).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner contended Hagiwara disclosed every element of the challenged claims. Hagiwara described a flexible polarography sensor for insertion into blood vessels to measure analytes, including glucose. Crucially, Hagiwara explicitly taught that while solid precious metal wires could be used for the electrode, a known alternative was to use a "base metal wire" with "precious metals vapor deposited or plated on the front ends thereof." Petitioner argued this directly disclosed the key sensor structure: a structurally flexible core (the base metal wire) and a surrounding layer of electrochemically active metal (the plating). Hagiwara further disclosed the method steps of inserting the sensor into a body and measuring electrical current to determine analyte concentration, thereby anticipating the claims.

Ground 3: Anticipation by Gross - Claims 1-3, 6, 10, and 11 are anticipated by Gross.

  • Prior Art Relied Upon: Gross (Patent 6,275,717).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted Gross disclosed a method and device for in vivo glucose measurement that anticipated the claims. Specifically, Figure 14 of Gross showed an alternative sensor construction comprising a stainless steel needle shaft (the core) on which a coating of platinum black is provided (the electrochemically active layer). The petition argued that this structure, used for measuring glucose concentration via current, meets all limitations of claim 1. The central technical argument was that the small-diameter (300 micron) stainless steel core disclosed in Gross is "structurally flexible" within the meaning of the ’202 patent.
  • Additional Grounds: Petitioner asserted that claim 5 is obvious over Hagiwara in view of Rosenblatt, arguing a POSITA would be motivated to use Rosenblatt’s platinum-coated tantalum core in Hagiwara’s flexible sensor for the same cost-saving reasons articulated in Ground 1.

4. Key Claim Construction Positions

  • "structurally flexible": Petitioner proposed this term be construed to mean "capable of being bent or flexed." This construction was argued to be consistent with the specification, which identifies tantalum and nitinol as examples of flexible materials. This interpretation was critical to Petitioner's arguments that the tantalum core of Rosenblatt and, more pointedly, the stainless steel core of Gross met this claim limitation.

5. Key Technical Contentions (Beyond Claim Construction)

  • Flexibility of Stainless Steel: A central technical contention, particularly for the Gross anticipation ground, was that a thin stainless steel wire (e.g., 300 microns in diameter as in Gross) is "structurally flexible." Petitioner argued that while bulk stainless steel may be considered rigid, at the small dimensions relevant to the patent, it exhibits significant flexibility. This argument was supported by comparing the Young's modulus of stainless steel to that of tantalum (an explicitly flexible material in the ’202 patent) and by referencing experimental evidence demonstrating that a 305-micron stainless steel wire can undergo significant, reversible flexure.

6. Relief Requested

  • Petitioner requested the institution of an inter partes review and the cancellation of claims 1-3, 5, 6, and 8-11 of the ’202 patent as unpatentable.