Arbmetrics, LLC v. Dexcom Inc.

Case: 20-1510    Document: 43      Page: 1   Filed: 12/31/2020

         NOTE: This disposition is nonprecedential.

   United States Court of Appeals
       for the Federal Circuit

                   ARBMETRICS, LLC,


                     DEXCOM INC.,


    Appeal from the United States District Court for the
 Southern District of California in No. 3:18-cv-00134-JLS-
 MSB, Judge Janis L. Sammartino.

                Decided: December 31, 2020

 Albritton P.C., Orland Park, IL, argued for plaintiff-appel-
 lant. Also represented by JOSEPH P. OLDAKER.

    RICHARD T. MULLOY, DLA Piper LLP (US), San Diego,
 CA, argued for defendant-appellee. Also represented by
 New York, NY.
Case: 20-1510      Document: 43      Page: 2     Filed: 12/31/2020

2                               ARBMETRICS, LLC   v. DEXCOM INC.

    Before WALLACH, TARANTO, and CHEN, Circuit Judges.
 CHEN, Circuit Judge.
      This appeal arises from an infringement action Ar-
 bmetrics, LLC (Arbmetrics) filed in the United States Dis-
 trict Court for the Southern District of California against
 Dexcom Inc. (Dexcom). Arbmetrics asserts that Dexcom’s
 Continuous Glucose Monitoring (CGM) systems infringe
 U.S. Patent No. 6,343,225 (’225 patent). Based on the dis-
 trict court’s claim constructions of either “emulsion” or “ox-
 ygen dissolving substance,” the parties stipulated that
 Dexcom’s accused products do not infringe the ’225 patent.
 See Arbmetrics, LLC v. Dexcom, Inc., No. 3:18-cv-00134,

2019 WL 7290541

(S.D. Cal. Dec. 30, 2019) (Claim Con-
 struction Order). Pursuant to the stipulation, the district
 court entered final judgment of noninfringement in favor of
 Dexcom. J.A. 2–4 (Stipulation); J.A. 7–8 (Final Judgment).
 Because we conclude that the district court did not err in
 its claim construction of oxygen dissolving substance, we
      The ’225 patent relates to “the field of electrochemical
 devices for detection and measurement purposes and more
 specifically an enzyme emulsion for use in an implantable
 miniature polarographic glucose sensor.” ’225 patent col. 1
 ll. 4–7. The glucose sensor of the ’225 patent is useful for
 long-term monitoring of blood glucose levels of individuals
 suffering from diabetes. Implantation of the device is
 “[p]referably . . . beneath the surface of the skin” or near
 the peritoneal cavity, putting the sensor directly in contact
 with biological fluids such as peritoneal or interstitial fluid,
 but not blood.

Id. at

col. 3 ll. 40–42, col. 6 ll. 58–67 (“All of
 the body tissues come into glucose equilibrium with the
 blood fairly rapidly[,] . . . [such that] placement of the de-
 vice in contact with the blood is not . . . required.”). The
 sensor includes a conductive electrode in contact with a sta-
 bilized enzyme emulsion comprising: (1) an oxidase
Case: 20-1510      Document: 43     Page: 3    Filed: 12/31/2020

 ARBMETRICS, LLC   v. DEXCOM INC.                             3

 enzyme (e.g., glucose oxidase) and (2) a compound in which
 oxygen is extremely soluble (e.g., a perfluorocarbon liquid).

Id. at

Abstract. The enzyme emulsion can be stabilized by
 crosslinking the proteins (i.e., the oxidase enzyme and any
 carrier proteins) in the emulsion to form a gel.

Id. at

col. 8
 ll. 29–41, col. 9 ll. 16–25.
      Measurement of the blood glucose level occurs via an
 electrochemical reaction.

Id. at

col. 2 ll. 43–58. In the pres-
 ence of oxygen, the oxidase enzyme oxidizes glucose, gen-
 erating hydrogen peroxide.

Id. The hydrogen peroxide

 then acts as an “electron carrier,” moving “electrons from
 glucose (by way of glucose oxidase) to the electrode.”

Id. at

 col. 11 ll. 34–39. At the surface of the electrode, removal of
 electrons from hydrogen peroxide results in a measurable

Id. Therefore, hydrogen peroxide

serves as a “di-
 rect measure” of blood glucose levels.

Id. at

col. 2 ll. 52–54.
      A challenge in developing glucose sensors is the limited
 amount of oxygen available to the oxidase enzyme.

Id. at

 col. 4 ll. 10–13. Unlike glucose, oxygen is poorly soluble in
 biological fluids, resulting in a high glucose-to-oxygen ra-

Id. at

col. 3 ll. 33–45. As a consequence, implantable
 glucose sensors “effectively measure [the amount of] oxy-
 gen instead of, or together with, [the amount of] glucose.”

Id. at

col. 4 ll. 10–17. Emulsifying the oxidase enzyme in
 the sensor with a compound in which oxygen is extremely
 soluble, as described in the invention of the ’225 patent,
 creates an oxygen reservoir, increasing the amount of oxy-
 gen available to the oxidase enzyme, reducing the elec-
 trode’s sensitivity to oxygen, and correcting the glucose-
 oxygen imbalance.

Id. at

col. 5 ll. 20–25, col. 8 l. 61–col. 9
 l. 6. Oxygen is no longer the limiting agent in the electro-
 chemical reaction, enabling accurate measurement of blood
 glucose levels.
     In January 2018, Arbmetrics filed a patent infringe-
 ment action against Dexcom asserting infringement of
 claims 1, 2, 5, 7, and 8 of the ’225 patent. J.A. 2. During
Case: 20-1510    Document: 43     Page: 4    Filed: 12/31/2020

4                             ARBMETRICS, LLC   v. DEXCOM INC.

 claim construction, the district court construed seven
 terms. On appeal, Arbmetrics disputes five of these con-
 structions. Claims 1 and 5 include the terms at issue.
     Claim 1 is directed to an implantable sensor and re-
    1. An implantable sensor for sensing a concentra-
    tion of an organic substrate, the sensor comprising:
    a conductive electrode; and
    a stabilized enzyme emulsion in contact with the
    electrode, the enzyme emulsion comprising:
    an oxidase enzyme that quantitatively oxidizes the
    organic substrate;
    a water immiscible oxygen dissolving substance
    emulsified into intimate contact with the enzyme
    to provide oxygen; and
    a protein crosslinking agent to crosslink and insol-
    ubilize the enzyme forming a stabilized gel com-
    prising crosslinked protein and particles of said
    oxygen dissolving substance.
 ’225 patent at claim 1 (emphases added to disputed terms).
    Claim 5 depends from claim 1 and recites:
    5. The implantable sensor of claim 1, wherein the
    oxygen dissolving substance is selected from the
    group consisting of perfluorocarbons, silicone oils,
    fluorosilicone oils, aromatic and aliphatic hydro-
    carbon oils or solids, carotenoids and steroids.

Id. at

claim 5 (emphases added to disputed terms).
      Relevant to this appeal, the district court adopted the
 following construction for oxygen dissolving substance: “a
 substance in which oxygen is preferentially soluble in com-
 parison to water.” Claim Construction Order, 

2019 WL 7290541

, at *9. The district court rejected Arbmetrics’s
Case: 20-1510      Document: 43     Page: 5   Filed: 12/31/2020

 ARBMETRICS, LLC   v. DEXCOM INC.                            5

 proposal to construe oxygen dissolving substance to mean
 “a substance (a particular kind of matter with uniform
 properties) having a higher oxygen solubility or higher ox-
 ygen permeability than at least one of a hydrocarbonaceous
 polymer and an oxyhydrocarbon polymer.”

Id. at

*8; J.A.
     In view of the Claim Construction Order, the parties
 stipulated the following: “Arbmetrics and Dexcom agree
 that all of Dexcom’s accused products do not meet either
 the ‘emulsion’ or the ‘oxygen dissolving substance’ limita-
 tions of all asserted claims of the ?225 patent as construed
 by the [district court].” J.A. 2. The district court then en-
 tered final judgment of noninfringement in favor of Dex-
 com. J.A. 7–8. Arbmetrics appeals to this court. We have
 jurisdiction over the appeal pursuant to 28 U.S.C.
 § 1295(a)(1).
      Arbmetrics challenges the district court’s construction
 of the following terms: “oxygen dissolving substance,”
 “emulsion,” “in contact with,” “electrode,” and “hydrocar-
 bon oils or solids.” We address only the district court’s con-
 struction of oxygen dissolving substance as it dispositive in
 view of Arbmetrics’s stipulation of noninfringement. See
 Starhome GmbH v. AT&T Mobility LLC, 

743 F.3d 849

, 854
 (Fed. Cir. 2014) (“Where, as here, a plaintiff concedes non-
 infringement by stipulation, we need only address the dis-
 trict court’s construction of the pertinent claim [term].”);
 see also Altiris, Inc. v. Symantec Corp., 

318 F.3d 1363

, 1368
 (Fed. Cir. 2003) (noting that when a party stipulates to
 noninfringement following claim construction, “we need
 only address the district court’s construction of the [rele-
 vant] claims”).
     Claim construction is a question of law. Teva Pharms.
 USA, Inc. v. Sandoz, Inc., 

135 S. Ct. 831

, 841–42 (2015).
 “[W]hen the district court reviews only evidence intrinsic
 to the patent (the patent claims and specifications, along
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6                              ARBMETRICS, LLC   v. DEXCOM INC.

 with the patent’s prosecution history),” we review that con-
 struction de novo.

Id. at

841. We review any “subsidiary
 factual findings [on extrinsic evidence] under the ‘clearly
 erroneous’ standard.”

Id. at

      Arbmetrics argues that the district court’s construction
 of oxygen dissolving substance is “incorrect for two reasons:
 (1) it incorrectly defines the term in relation to the [oxygen]
 solubility of water instead of adopting the patentee’s dis-
 claiming statements made during prosecution, and (2) it
 defines the term only in relation to solubility instead of sol-
 ubility or permeability.” Appellant’s Br. at 22. Pointing to
 the prosecution history, Arbmetrics contends that patentee
 excluded graphite, nylon, polyethylene, and polystyrene
 from the definition of oxygen dissolving substance when
 distinguishing the invention over the prior art, an “une-
 quivocal disclaimer that must be accounted for in the con-
 struction of the term ‘oxygen dissolving substance.’”

Id. at

 23. Regarding inclusion of permeability as an alternative
 to solubility in the term’s construction, Arbmetrics argues
 that “the ’225 patent specification uses the concepts of ox-
 ygen permeability and solubility interchangeably in the
 context of a material’s ‘oxygen dissolving’ properties.”

Id. at

27. Arbmetrics thus concludes “that the term ‘oxygen
 dissolving substance’ should be construed to mean: ‘a sub-
 stance having a higher oxygen solubility or higher oxygen
 permeability than particles of graphite, polyethylene, pol-
 ystyrene, and nylon.’”

Id. at

28. We disagree.
     While we begin our claim construction analysis with
 the language of the claim itself, see Phillips v. AWH Corp.,

415 F.3d 1303

, 1312 (Fed. Cir. 2005) (en banc), the claims
 “do not stand alone. Rather, they are part of ‘a fully inte-
 grated written instrument,’ . . . consisting principally of a
 specification that concludes with the claims,”

id. at 1315

 (quoting Markman v. Westview Instruments, Inc., 

52 F.3d 967

, 978 (Fed. Cir. 1995) (en banc)). “For that reason,
 claims ‘must be read in view of the specification, of which
 they are a part.’” 

Phillips, 415 F.3d at 1315

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 ARBMETRICS, LLC   v. DEXCOM INC.                            7


Markman, 52 F.3d at 979

). Additionally, we recognize that
 “the prosecution history can often inform the meaning of
 the claim language by demonstrating how the inventor un-
 derstood the invention.”

Id. at

1317. But the prosecution
 history “is less useful for claim construction” than the claim
 language and written description.

Id. The written description

supports the district court’s
 use of water rather than substances such as graphite and
 polyethylene as the benchmark for construing oxygen dis-
 solving substance. A goal of the ’225 patent’s invention is
 to address “impediments to successful implantable glucose
 sensors.” ’225 patent col. 3 ll. 33–45. These impediments
 include the limited availability of oxygen—due to its poor
 solubility—in the biological fluids surrounding the sensor.

Id. Because the oxygen

dissolving substance functions to
 resolve this issue by concentrating oxygen in the sensor,
 that substance must be one in which oxygen has a greater
 solubility than it does in the surrounding biological fluids.
 See Apple Comput., Inc. v. Articulate Sys., Inc., 

234 F.3d 14

, 25 (Fed. Cir. 2000) (“[A] claim must be interpreted in
 light of the teachings of the written description and pur-
 pose of the invention described therein.”).
      Importantly, the solubility of oxygen in the surround-
 ing biological fluids is close to the solubility of oxygen in
 water, 1 making water a suitable proxy for the fluids. More-
 over, the written description disparages water as a poor ox-
 ygen dissolving substance as compared to the examples of
 substances the patent identifies as serving as an oxygen
 dissolving substance for purposes of the invention. See,
 e.g., ’225 patent col. 10 ll. 25–30 (“Because the perfluoro-
 carbon is emulsified into tiny particles, there is an intimate

     1   At oral argument, Arbmetrics acknowledged that
 the solubility of oxygen in the bodily fluids abutting the
 glucose sensor was close to the solubility of oxygen in wa-
 ter. Oral Arg. at 2:55–4:20.
Case: 20-1510     Document: 43      Page: 8    Filed: 12/31/2020

8                              ARBMETRICS, LLC   v. DEXCOM INC.

 association between the oxygen carrying perfluorocarbon
 and the oxygen-requiring enzyme. This limits the distance
 that oxygen must diffuse through a poor oxygen carrier
 such as water.”); col. 13 ll. 2–4 (“An advantage is that ster-
 oids, like perfluorocarbons, are much better at dissolving
 oxygen than is water.”). We therefore agree with the dis-
 trict court that, in view of the written description, water is
 the correct benchmark for construing oxygen dissolving
     Turning next to the prosecution history, nothing
 therein dictates use of an alternative benchmark or con-
 struction. Arbmetrics argues that graphite, nylon, polyeth-
 ylene, and polystyrene, i.e., substances allegedly
 disclaimed during prosecution, see Appellant’s Br. at 23,
 are the appropriate references for construing the term ox-
 ygen dissolving substance. But use of these substances as
 benchmarks would broaden the claims beyond what is dis-
 closed in the written description: graphite, nylon, polyeth-
 ylene, and polystyrene all have lower oxygen solubility
 than water. 2 See J.A. 3483 (“Oxygen is not preferentially
 soluble in graphite—it is barely soluble at all. Nor is oxy-
 gen particularly soluble in nylon, polyethylene, or polysty-
 rene.”). Accordingly, Arbmetrics’s suggested construction
 is impermissible as “[r]epresentations [made] during pros-
 ecution cannot enlarge the content of the specification.” Bi-
 ogen, Inc. v. Berlex Labs., Inc., 

318 F.3d 1132

, 1140 (Fed.
 Cir. 2003); see also Honeywell Int’l, Inc. v. ITT Indus., Inc.,

452 F.3d 1312

, 1319 (Fed. Cir. 2006) (“Where, as here, the
 written description clearly identifies what his invention is,

     2    At oral argument, Arbmetrics explained that it
 wanted the term oxygen dissolving substance to capture a
 wider range of substances and that graphite, nylon, poly-
 ethylene, and polystyrene have a decidedly lower oxygen
 solubility than water or bodily fluids. Oral Arg. at 5:02–
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 ARBMETRICS, LLC   v. DEXCOM INC.                             9

 an expression by a patentee during prosecution that he in-
 tends his claims to cover more than what his specification
 discloses is entitled to little weight.”). Arbmetrics’s pro-
 posed construction, which relies on a benchmark that is
 “barely soluble at all,” is also plainly inconsistent with the
 purpose of the invention: to create an oxygen reservoir in
 the glucose sensor through use of a substance with high
 oxygen solubility.
      Last, we cannot accept Arbmetrics’s proposal to include
 permeability as an alternative to solubility in the construc-
 tion of oxygen dissolving substance. Appellant’s Br. at 26,
 28 (submitting that either “higher oxygen solubility or
 higher oxygen permeability” can be used as measures of a
 substance’s oxygen dissolving properties (emphasis
 added)). Although the written description may contem-
 plate oxygen dissolving substances having both high oxy-
 gen solubility and permeability, see ’225 patent col. 8 ll. 48–
 54, nothing in the claims, written description, or prosecu-
 tion history supports an understanding of “oxygen dissolv-
 ing substance” as having high oxygen permeability without
 high oxygen solubility. As a result, we agree with the dis-
 trict court that “permeability has no place in the construc-
 tion of this term.” Claim Construction Order, 

2019 WL 7290541

, at *8.
     Thus, we affirm the district court’s claim construction
 that an “oxygen dissolving substance” is “a substance in
 which oxygen is preferentially soluble in comparison to wa-
 ter.” Because the district court’s construction is correct and
 Arbmetrics conceded noninfringement by stipulation un-
 der this construction, we affirm the judgment of nonin-
     We have considered the parties’ remaining arguments
 but find them unpersuasive. For the foregoing reasons, we
 conclude that the district court properly construed the term
Case: 20-1510     Document: 43   Page: 10   Filed: 12/31/2020

 10                           ARBMETRICS, LLC   v. DEXCOM INC.

 oxygen dissolving substance and properly entered final
 judgment of noninfringement. Therefore, we affirm.
      Costs to appellee.

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