Case: 22-1631    Document: 48     Page: 1   Filed: 09/12/2023




        NOTE: This disposition is nonprecedential.


   United States Court of Appeals
       for the Federal Circuit
                  ______________________

                MASIMO CORPORATION,
                      Appellant

                             v.

                      APPLE INC.,
                         Appellee
                  ______________________

 2022-1631, 2022-1632, 2022-1633, 2022-1634, 2022-1635,
            2022-1636, 2022-1637, 2022-1638
                ______________________

     Appeals from the United States Patent and Trademark
 Office, Patent Trial and Appeal Board in Nos. IPR2020-
 01520, IPR2020-01521, IPR2020-01536, IPR2020-01537,
 IPR2020-01538,       IPR2020-01539,      IPR2020-01714,
 IPR2020-01715.
                  ______________________

                Decided: September 12, 2023
                  ______________________

    STEPHEN W. LARSON, Knobbe, Martens, Olson & Bear,
 LLP, Irvine, CA, argued for appellant. Also represented by
 STEPHEN C. JENSEN, JAROM D. KESLER, JOSEPH R. RE;
 JEREMIAH HELM, Washington, DC.

     LAUREN ANN DEGNAN, Fish & Richardson P.C., Wash-
 ington, DC, argued for appellee. Also represented by
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 2                         MASIMO CORPORATION v. APPLE INC.




 CHRISTOPHER DRYER, JARED HARTZMAN, WALTER KARL
 RENNER; ASHLEY BOLT, Atlanta, GA.
               ______________________

  Before LOURIE, PROST, and CUNNINGHAM, Circuit Judges.
 LOURIE, Circuit Judge.
      Masimo Corp. (“Masimo”) appeals from eight final
 written decisions of the United States Patent and Trade-
 mark Office (“USPTO”) Patent Trial and Appeal Board
 (“the Board”) holding nearly all claims of U.S. Patents
 10,258,265 (“the ’265 patent”), 10,292,628 (“the ’628 pa-
 tent”), 10,577,553 (“the ’553 patent”), 10,588,554 (“the ’554
 patent”), and 10,631,765 (“the ’765 patent”) (collectively,
 “the challenged patents”) unpatentable as obvious. Apple
 Inc. v. Masimo Corp., IPR2020-01520, 

 (P.T.A.B. Feb. 23, 2022) (“’1520 Decision”), J.A. 1–106; Ap-
 ple Inc. v. Masimo Corp., IRPR2020-01521, 

 (P.T.A.B. Apr. 11, 2022) (“’1521 Decision”), J.A.
 107–98; Apple Inc. v. Masimo Corp., IPR2020-01536, 

 (P.T.A.B. Feb. 23, 2022) (“’1536 Decision”), J.A.
 199–276; Apple Inc. v. Masimo Corp., IPR2020-01537, 

 (P.T.A.B. Feb. 23, 2022) (“’1537 Decision”), J.A.
 277–358; Apple Inc. v. Masimo Corp., IPR2020-01538, 

 (P.T.A.B. Feb. 23, 2022) (“’1538 Decision”), J.A.
 359–428; Apple Inc. v. Masimo Corp., IRPR2020-01539,
 

 (P.T.A.B. Feb. 23, 2022) (“’1539 Deci-
 sion”), J.A. 429–514; Apple Inc. v. Masimo Corp., IPR2020-
 01714, 

 (P.T.A.B. Apr. 6, 2022) (“’1714
 Decision”), J.A. 515–91; Apple Inc. v. Masimo Corp.,
 IPR2020-01715, 

 (P.T.A.B. Apr. 6, 2022)
 (“’1715 Decision”), J.A. 592–675. For the reasons articu-
 lated below, we reverse-in-part and affirm-in-part.
                        BACKGROUND
     The challenged patents, all assigned to Masimo, are di-
 rected to an optical sensor for noninvasively measuring
 blood constituents, including a protruding, convex cover
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 MASIMO CORPORATION v. APPLE INC.                              3



 positioned over multiple light detectors and emitters. Rep-
 resentative claim 1 of the ’628 patent is reproduced below.
    1. A noninvasive optical physiological sensor com-
    prising:
    a plurality of emitters configured to emit light into
    tissue of a user;
    a plurality of detectors configured to detect light that
    has been attenuated by tissue of the user, wherein
    the plurality of detectors comprise at least four de-
    tectors;
    a housing configured to house at least the plurality
    of detectors; and
    a light permeable cover configured to be located be-
    tween tissue of the user and the plurality of detec-
    tors when the noninvasive optical physiological
    sensor is worn by the user, wherein the cover com-
    prises an outwardly protruding convex surface con-
    figured to cause tissue of the user to conform to at
    least a portion of the outwardly protruding convex
    surface when the noninvasive optical physiological
    sensor is worn by the user and during operation of
    the noninvasive optical physiological sensor, and
    wherein the plurality of detectors are configured to
    receive light passed through the outwardly protrud-
    ing convex surface after attenuation by tissue of the
    user.
 ’628 patent, col. 44 ll. 36–56.
     Apple Inc. (“Apple”) petitioned for review of the five
 challenged patents, asserting three primary references,
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 4                         MASIMO CORPORATION v. APPLE INC.




 Aizawa, 1 Mendelson-1988, 2 and/or Mendelson-799, 3 in
 combination with at least one of three secondary refer-
 ences, Inokawa, 4 Ohsaki, 5 and/or Mendelson-2006. 6 Ai-
 zawa discloses a wrist, palm-side sensor for detecting a
 pulse with a single, central emitter and a “plate-like mem-
 ber” to “improve adhesion” (e.g., contact between the sensor
 and a user’s skin). Aizawa, Figs. 1(a), 1(b), 2, ¶ 13. Men-
 delson-1988 discloses a flat, forehead oxygen sensor with
 multiple detectors around a central emitter. Mendelson-
 1988, Fig. 2. Mendelson-799 discloses a similar arrange-
 ment but with three centrally clustered emitters. Mendel-
 son-799, Fig. 7.        Mendelson-2006 focuses on the
 transmission of data from an optical sensor. Mendelson-
 2006, Abstract. Inokawa discloses a wrist sensor with a
 convex cover, emitters on the periphery, and a single detec-
 tor in the center. Inokawa, ¶¶ 58–59, Fig. 2. Ohsaki


     1    U.S. Patent Application Publication 2002/0188210
 A1 (filed May 23, 2002, published Dec. 12, 2002), J.A.
 3242–48 (“Aizawa”).
     2    Yitzhak Mendelson et al., Design and Evaluation
 of a New Reflectance Pulse Oximeter Sensor, 22 ASS’N FOR
 THE ADVANCEMENT OF MED. INSTRUMENTATION 167 (1988),
 J.A. 3358–64 (“Mendelson-1988”).
     3    U.S. Patent 6,801,799 B2 (filed Feb. 6, 2003, issued
 Oct. 5, 2004), J.A. 155578–93 (“Mendelson-799”).
     4    Japanese Patent Application Published 2006-
 296564 A (filed Apr. 18, 2005, published Nov. 2, 2006), J.A.
 3249–95 (“Inokawa”).
     5    U.S. Patent Application Publication 2001/0056243
 A1 (filed May 11, 2001, published Dec. 27, 2001), J.A.
 3352–57 (“Ohsaki”).
     6    YITZHAK MENDELSON ET AL., A WEARABLE
 REFLECTANCE        PULSE     OXIMETER       FOR     REMOTE
 PHYSIOLOGICAL MONITORING (Proceedings of the 28th
 IEEE EMBS Annual International Conference, Aug. 30–
 Sep. 3, 2006), J.A. 23200–03 (“Mendelson-2006”).
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 MASIMO CORPORATION v. APPLE INC.                           5



 discloses a sensor with a convex cover worn on the “back
 side” (i.e.., watch side) of a user’s wrist and that reduces
 slippage. Ohsaki, Abstract; see also 

 at Fig. 1, ¶ 23.
     In the eight inter partes review (“IPR”) proceedings,
 Apple asserted a variety of motivations to combine the as-
 serted references, including: (1) improved light collection,
 (2) improved adhesion, (3) improved detection efficiency,
 and (4) improved protection of the sensor elements. The
 improved light collection theory was based, in part, on
 what the Board and parties referred to as the “greatest cur-
 vature theory,” meaning that light concentration would in-
 crease where the curvature of a lens’s surface is the
 greatest—in Apple’s proposed combinations, allegedly at
 the peripheral detectors, not directly at the center.
     Masimo challenged each of the proffered motivations to
 combine, including arguing that (1) a convex lens would
 condense light toward the center, away from the peripheral
 detectors in Apple’s combinations; (2) Apple’s arguments
 contradicted admissions made by its expert witness; and
 (3) Ohsaki only teaches improved adhesion with a watch-
 side sensor, and the same benefits would not be achieved
 with Aizawa’s palm-side sensor, which achieves adhesion
 through its flat plate. Masimo further argued that the
 greatest curvature theory was belatedly raised in Apple’s
 Reply Brief. In addition, Masimo challenged Apple’s as-
 serted reasonable expectations of success and the refer-
 ences’ alleged disclosure of every claim element, including
 the specific protrusion heights required by claims 11, 17,
 and 28 of the ’554 patent and claims 12, 18, and 29 of the
 ’765 patent.
     The Board ultimately found that each challenged claim
 would have been obvious over the combination of refer-
 ences, except for independent claim 13 of the ’554 patent.
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 6                                 MASIMO CORPORATION v. APPLE INC.




 Across the eight IPRs, the Board found the following moti-
 vations to combine7:

     Combinations Appealed               Board’s Found Motiva-
       (Relevant Claims)                   tion(s) to Combine
  Aizawa-Inokawa                        Improve light collection
  ’1520 IPR: all challenged claims
  ’1521 IPR: all challenged claims

  Aizawa-Inokawa-Ohsaki                 Improve adhesion
  ’1520 IPR: all challenged claims      Improve detection efficiency
  ’1521 IPR: all challenged claims

  Aizawa-Inokawa-Ohsaki                 Improve adhesion
  ’1537 IPR: claims 1–6, 9–18,          Improve detection efficiency
  20–24, 29                             Protect sensor elements

  Aizawa-Inokawa-Ohsaki-                Improve adhesion
  Mendelson-2006                        Improve detection efficiency
  ’1537 IPR: claims 7, 10               Protect sensor elements
  ’1539 IPR: all challenged claims
  ’1715 IPR: all challenged claims

  Mendelson-1988-Inokawa                Improve light collection
  ’1520 IPR: claims 1, 2, 4, 14,
  17–25, 26–30
  ’1521 IPR: all challenged claims

  Mendelson-799-Ohsaki                  Improve adhesion
  ’1536 IPR: all challenged claims      Improve detection efficiency
  ’1538 IPR: all challenged claims      Protect sensor elements




      7  This chart is based on a chart included in Appellee
 Br. at 21. Masimo did not dispute that the chart was an
 accurate summary of the Board’s motivation to combine
 findings.
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 MASIMO CORPORATION v. APPLE INC.                                7



   Combinations Appealed                 Board’s Found Motiva-
     (Relevant Claims)                     tion(s) to Combine
  ’1714 IPR: all challenged claims

    Masimo appealed to this court. We have jurisdiction
 under 

(a)(4)(A).
                            DISCUSSION
     Masimo raises a number of arguments on appeal,
 which fall into five main categories: (1) that the Board
 erred in relying on theories not raised by either party, (2)
 that the Board erred in failing to consider contrary evi-
 dence and admissions, (3) that the Board erred in relying
 on the allegedly belatedly raised “greatest curvature the-
 ory,” (4) that the Board’s factual findings underlying its ob-
 viousness determination were unsupported by substantial
 evidence, and (5) that the Board erred in finding that de-
 pendent claims 14–18 of the ’554 patent would have been
 obvious when it found independent claim 13 nonobvious.
 We address each argument in turn.
                                     I
     Masimo argues that, in rendering its decisions, the
 Board relied on its own theories not asserted by either
 party, thereby depriving it of the opportunity to respond.
     In the ’1520 and ’1521 IPRs, in response to Masimo’s
 argument that Aizawa’s plate’s flatness provided its adhe-
 sion benefits, the Board found that Aizawa’s “improved ad-
 hesion is provided by the acrylic material . . . not the flat
 surface.” ’1520 Decision at *28; ’1521 Decision at *27.
 Masimo alleges that Apple never argued that. Appellant
 Br. at 50–51. Rather, it argues, Apple’s expert testified
 that Aizawa’s plate “doesn’t explicitly require the use of
 acrylic” and that one “can obtain the benefits associated
 with Aizawa” by using materials including but not limited
 to acrylic. J.A. 5427, 133:5–9; J.A. 5428, 134:12–14.
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 8                          MASIMO CORPORATION v. APPLE INC.




      In the ’1537, ’1539, and ’1715 IPRs, in response to
 Masimo’s argument that Ohsaki’s longitudinal protrusion
 successfully achieves improved adhesion by interacting
 with a user’s wrist bones, the Board found that a circular
 sensor like that in Aizawa “would also avoid the bones in
 the forearm if [the sensor] were slightly smaller.” ’1537
 Decision at *21; ’1539 Decision at *22; ’1715 Decision at
 *22. Masimo alleges that Apple never argued that, and
 that there is no evidence that a person of ordinary skill in
 the art would have reduced Aizawa’s sensor size, particu-
 larly when it was already “small.” Appellant’s Br. at 65–66
 (citing Mendelson-2006).
     Under the Administrative Procedure Act’s notice pro-
 visions, as relevant to Board proceedings, patent owners
 “shall be timely informed of . . . the matters of fact and law
 asserted” in IPRs, 

(b)(3), and the Board
 “shall give all interested parties opportunity for . . . the
 submission and consideration of facts [and] arguments,” 

 § 554(c)(1). The Board, therefore, “must base its decision
 on arguments that were advanced by a party, and to which
 the opposing party was given a chance to respond.” In re
 Magnum Oil Tools Int’l, Ltd., 

 (Fed.
 Cir. 2016); see also Apple Inc. v. Corephotonics, Ltd., No.
 2022-1350, slip op. at 13 (Fed. Cir. Sep. 11, 2023) (finding
 the Board erred when its analysis focused on “an issue that
 no party meaningfully raised or asserted was relevant”);
 Alacritech, Inc. v. Intel Corp., 

, 1372 (Fed.
 Cir. 2020) (finding that the Board erred where its “reason-
 ing appear[ed] to be untethered to either party’s position”).
      The Board may in certain circumstances rely on its own
 readings of references. Belden Inc. v. Berk-Tek LLC, 

 (Fed. Cir. 2005). These readings, however,
 must still “be supported by substantial evidence, and its
 decisions must be reached only after the parties have been
 provided fair notice and an opportunity to be heard.” Ap-
 ple, No. 2022-1350 at 14–15.
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 MASIMO CORPORATION v. APPLE INC.                            9



      The Board’s conclusions on those two points were not
 supported by the petitions nor merely “simple point[s]” that
 the Board could have easily deduced from the face of the
 reference. Belden, 

. Indeed, Apple does
 not argue that it presented those theories at any point in
 the IPRs. See Appellee Br. at 34–36. However, even if the
 Board may have erred in relying on its own theories, that
 is of no consequence here because they are not essential to
 its determinations.
     The Board relied on those allegedly new arguments in
 rejecting Masimo’s arguments against adhesion as a moti-
 vation to combine. But adhesion is not the only motivation
 to combine that the Board relied on. The Board also found
 that improved light collection, improved detection effi-
 ciency and, in all but the ’1520 and ’1521 IPRs, improved
 protection of the sensor elements provided motivations to
 combine the asserted references. See infra, Section IV.A;
 Oral Arg. at 11:42–51 (“And you see that whenever the
 Board relied on the motivation to increase adhesion, with
 Ohsaki, then the Board would also rely on a motivation to
 provide protection.”). Therefore, even if the Board erred by
 relying on these theories as part of its finding of adhesion
 as a motivation to combine, it was, at most, harmless error.
                               II
     Masimo argues that the Board failed to consider evi-
 dence and admissions by Apple and its expert witness that
 were contrary to the Board’s findings. Masimo cites sev-
 eral nonprecedential opinions in support of its argument.
 See Appellant Br. at 32–33 (first citing Cook Grp. Inc. v.
 Boston Sci. Scimed, Inc., 

, 999 (Fed. Cir.
 2020) (“The Board erred in refusing to consider [peti-
 tioner’s] admission[s] when it was weighing the evi-
 dence . . . .”); and then citing PPC Broadband, Inc. v. Iancu,
 

, 623 (Fed. Cir. 2018) (vacating obvious-
 ness decision where Board failed to address expert’s admis-
 sions)). Masimo is correct that the Board has an obligation
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 10                         MASIMO CORPORATION v. APPLE INC.




 to look at evidence properly before it, even if it detracts
 from its determination. See Parus Holdings, Inc. v. Google
 LLC, 

 (Fed. Cir. 2023) (discussing Aqua
 Prods. v. Matal, 

 (Fed. Cir. 2017) (en
 banc)). However, the Board did consider the evidence and
 argument that Masimo claims were overlooked. The Board
 simply rejected those arguments or found the contrary ev-
 idence outweighed by other supporting evidence.
      Masimo asserts that at least the following allegations
 were not properly considered: (1) Apple’s and its expert’s
 alleged admission that a convex cover would concentrate
 light toward the sensor’s center, rather than toward the pe-
 ripheral detectors, (2) Aizawa’s alleged teaching of its flat
 plate providing benefits, e.g., adhesion, (3) Inokawa’s al-
 leged failure to teach benefits of a convex lens, (4) the pro-
 posed combination’s elimination of Ohsaki’s convex cover
 aligning with a user’s wrist bones, and (5) the proposed
 combination’s potential creation of air gaps between the
 sensor and a user’s skin. But the Board considered each of
 those allegations. For example, as discussed above, the
 Board considered and rejected Masimo’s argument that Ai-
 zawa’s adhesion benefits were attributable to its sensor
 cover being flat and the alignment of Ohsaki’s protrusion
 with wrist bones. See, supra, Section I. The Board also
 thoroughly considered whether light would be condensed
 at the center, or elsewhere, citing testimony of Apple’s ex-
 pert stating that the light-focusing properties of a convex
 lens do not demonstrate “that a convex lens directs all light
 to the center.” See, e.g., ’1521 Decision at *20, 22–24. The
 Board also found that Apple did “not propose including any
 air gaps” in its combination. See, e.g., ’1536 Decision at *18.
 And the Board found that “Inokawa demonstrates that it
 was known in the art prior to the ’265 patent to use a lens
 to focus diffuse light reflected from body tissue on to the
 light detecting elements of a wrist-worn pulse sensor, to in-
 crease the light gathered by the sensor and thereby
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 MASIMO CORPORATION v. APPLE INC.                          11



 improve the device’s calculation of the user’s pulse.” See,
 e.g., ’1520 Decision at *20.
     The Board therefore did not fail to consider evidence or
 argument. Rather, it considered all of Masimo’s points; it
 just did not reach the conclusions that Masimo desired.
                              III
     Masimo argues that the Board erred in relying on Ap-
 ple’s greatest curvature theory as a motivation to combine
 because it was allegedly included for the first time in Ap-
 ple’s Reply. 8 All arguments must be included in the peti-
 tion. VLSI Tech. LLC v. Intel Corp., 

, 654 (Fed.
 Cir. 2022) (“[T]he petition defines the scope of the IPR pro-
 ceeding and [] the Board must base its decision on argu-
 ments that were advanced by a party and to which the
 opposing party was given a chance to respond.”). However,
 a party is “not barred from elaborating on [its] arguments
 on issues previously raised.” Chamberlain Grp., Inc. v. One
 World Techs., Inc., 

 (Fed. Cir. 2019). That
 type of elaboration is particularly permissible when it re-
 buts arguments raised by the other party. See, e.g., Provi-
 sur Techs., Inc. v. Weber, Inc., 

, 122 (Fed. Cir.
 2022) (finding the petitioner’s reply proper when it was “di-
 rectly responsive” to the patent owner’s arguments).
     We review the Board’s decisions regarding the scope of
 proper reply material for an abuse of discretion. Ericsson
 Inc. v. Intell. Ventures I LLC, 

 (Fed.


     8    Masimo additionally points to a number of other
 theories it alleges Apple pursued without including them
 in its petitions, Appellant Br. at 33–34, but only mentions
 these in passing. We do not consider arguments that are
 not fully developed. See, e.g., Monsanto Co. v. Scruggs, 

 (Fed. Cir. 2006) (“In order for this court to
 reach the merits of an issue on appeal, it must be ade-
 quately developed.”).
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 12                         MASIMO CORPORATION v. APPLE INC.




 Cir. 2018). The Board abuses its discretion if its decision:
 “(1) is clearly unreasonable, arbitrary, or fanciful; (2) is
 based on an erroneous conclusion of law; (3) rests on clearly
 erroneous fact finding; or (4) involves a record that contains
 no evidence on which the Board could rationally base its
 decision.” Intelligent Bio-Sys., Inc. v. Illumina Cambridge
 Ltd., 

 (Fed. Cir. 2016).
     The Board did not abuse its direction in considering the
 greatest curvature theory. Apple’s petitions and its initial
 expert declarations stated and explained that the proposed
 combination would increase light-gathering. J.A. 1896–99;
 J.A. 3053–54, ¶¶ 95–97. Its expert’s reply declarations
 merely further expanded on that theory and rebutted
 Masimo’s arguments that light gathering would only in-
 crease at the center of the sensor. Pat. Owner Resp. at 15–
 40, J.A. 2212–37; J.A. 4531–42, ¶¶ 8–23. The Board there-
 fore did not abuse its discretion in relying on that theory.
                              IV
     Masimo argues that factual findings underlying the
 Board’s ultimate conclusion of obviousness are not sup-
 ported by substantial evidence. The ultimate conclusion of
 obviousness is a legal determination based on underlying
 factual findings, including whether or not a relevant arti-
 san would have had a motivation to combine references in
 the manner required to achieve the claimed invention.
 Henny Penny Corp. v. Frymaster LLC, 

 (Fed. Cir. 2019) (citing Wyers v. Master Lock Co., 

, 1238–39 (Fed. Cir. 2010)). We review the Board’s ob-
 viousness determination de novo, but its factual findings
 for substantial evidence. E.g., Game & Tech. Co. v. War-
 gaming Grp. Ltd., 

 (Fed. Cir. 2019).
 Substantial evidence exists when, reviewing the record as
 a whole, “a reasonable fact finder could have arrived at” the
 finding on review. In re Gartside, 

 (Fed. Cir. 2000).
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 MASIMO CORPORATION v. APPLE INC.                         13



     Masimo makes a number of arguments against obvi-
 ousness, but focuses on the Board’s findings regarding (a)
 motivation to combine, (b) reasonable expectation of suc-
 cess, (c) the obviousness of ’265 patent claims 12 and 14,
 which require a reduction in the “mean path length” of
 light, (d) whether or not the Aizawa-Inokawa combination
 discloses all the claim elements, and (e) the obviousness of
 ’554 patent claims 11, 17, and 28 and ’765 patent claims 12,
 18, and 29 that recite specific protrusion height ranges. We
 address each of those arguments below.
                              A
     First, Masimo challenges all of the motivations to com-
 bine found by the Board. See, supra, Background.
     Many of Masimo’s arguments regarding motivation to
 combine attack the Board’s reliance on the greatest curva-
 ture theory, which provides support for improved light col-
 lection in certain of Apple’s asserted combinations.
 However, that is not the sole basis for the Board’s finding
 of a motivation to combine in any one IPR or for any one
 combination. Rather, the Board relies on multiple motiva-
 tions to combine or a more generalized finding that the
 combination would improve light collection. As counsel for
 Apple stated at oral argument, even were we to find the
 greatest curvature theory problematic, we could still affirm
 the Board’s finding. See Oral Arg. at 17:33–18:41.
     Apple’s asserted motivation of improved light collection
 rested on the premise that the nature of light itself would
 cause a convex lens to increase light gathering. The great-
 est curvature theory was simply a rebuttal to Masimo’s ar-
 gument that light would not be directed to the peripherally
 positioned detectors. See, e.g., id. The Board’s analysis in
 its decisions confirm that understanding. For example, in
 the ’1520 IPR, the Board pointed to an annotated version
 of Inokawa Figure 2 created by Apple’s expert that showed
 “the various directions that light rays may be directed,”
 creating “backscattered light that is diffuse, rather than
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 14                           MASIMO CORPORATION v. APPLE INC.




 collimated, in nature.” ’1520 Decision at *20. The Board
 found that that “suggests that a lens might be useful to in-
 crease the amount of collected light and thereby increase
 the reliability of the pulse data generated using the col-
 lected light.” Id. The Board further found that Inokawa
 further supported that theory:
      [I]n a general sense, Inokawa demonstrates that it
      was known in the art prior to the ’265 patent to use
      a lens to focus diffuse light reflected from body tissue
      on to the light detecting elements of a wrist-worn
      pulse sensor, to increase the light gathered by the
      sensor and thereby improve the device’s calculation
      of the user's pulse. Inokawa also discloses, in its Fig-
      ure 2, that a convexly protruding lens may advanta-
      geously be used for this purpose.
 Id. Those findings, and Inokawa’s teachings, are distinct
 from the greatest curvature theory. Indeed, neither party
 asserts that Inokawa discusses the greatest curvature the-
 ory. See, e.g., Appellant Br. at 40. That the Board found
 that the greatest curvature theory provided additional
 support for improved light capture as a motivation does not
 impact whether the Board had evidentiary support for its
 conclusion that “a lens might be useful to increase the
 amount of collected light and thereby increase the reliabil-
 ity of the pulse data generated using the collected light.”
 ’1520 Decision at *20. And, given Apple’s expert testimony
 and Inokawa, we conclude that finding was supported by
 substantial evidence. We therefore do not need to reach
 the more specific issue whether the greatest curvature the-
 ory is supported by substantial evidence.
     We further conclude that, in certain IPRs, protection of
 the sensor elements provides an alternative or additional
 motivation to combine. Masimo argues that a convex cover
 provides no more protection than a flat cover, and that a
 convex cover would be more prone to scratches, making it
 undesirable. But the Board already found that a convex
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 MASIMO CORPORATION v. APPLE INC.                            15



 cover would protect sensor elements, which was not dis-
 puted by Masimo, and that the potential for scratches was
 but one tradeoff that a person of ordinary skill in the art
 would consider. ’1537 Decision at *24–25 (citing Oral
 Hearing Tr. at 64:6–65:5). Masimo’s arguments that that
 motivation is not supported by substantial evidence there-
 fore largely amount to asking us to reweigh the evidence
 already considered by the Board, which we decline to do.
 “A finding is supported by substantial evidence if a reason-
 able mind might accept the evidence as adequate to sup-
 port the finding.” Henny Penny Corp. v. Frymaster, LLC,
 

 (Fed. Cir. 2019). The Board’s determi-
 nations that protection provided a motivation to combine
 was thus supported by substantial evidence.
      Because we conclude that the Board’s findings regard-
 ing improved light collection and protection of sensor ele-
 ments were supported by substantial evidence, we do not
 need to consider the issues of adhesion and the related ben-
 efit of improved detection efficiency.
                               B
     In addition to challenging the Board’s findings on mo-
 tivation to combine, Masimo asserts that the Board’s find-
 ings that there would have been a reasonable expectation
 of success were not supported by substantial evidence. Its
 main argument is that the Board ignored Apple’s expert
 testimony regarding the complexity of designing a physio-
 logical sensor. See, e.g., Appellant Br. at 53–56, 68, 78–79.
 However, much of the complexity that Masimo points to is
 tied to specific goals, such as improving light collection, and
 perfecting the sensor structure. The claims themselves re-
 quire no specific benefits. Rather, they simply require a
 noninvasive optical physiological sensor comprising cer-
 tain elements. Apple only needed to show that a person of
 ordinary skill in the art would have had a reasonable ex-
 pectation of success in arriving at the claimed invention,
 not an ideal optical sensor. E.g., Intelligent Bio-Sys, Inc.,
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 16                         MASIMO CORPORATION v. APPLE INC.




 

 (“The reasonable expectation of success
 requirement refers to the likelihood of success in combining
 references to meet the limitations of the claimed inven-
 tion.”). Masimo’s arguments regarding reasonable expec-
 tations of success are therefore without merit.
                               C
     Masimo separately argues that the Board’s findings re-
 garding the obviousness of ’265 patent claims 12 and 14,
 which require a reduction in the “mean path length” of
 light are not supported by substantial evidence. Apple’s
 support for the alleged disclosure of a reduction of mean
 path length rests on the theory that, with a convex lens,
 “refraction of the incoming reflected light can shorten the
 path of the light before it reaches the detector . . . because
 the incoming light is ‘condensed’ toward the center.” J.A.
 3068–70, ¶¶ 119–20. According to Masimo, that theory
 contradicts the greatest curvature theory, which assumes
 that light is concentrated at the detectors. Masimo argues
 that the Board’s findings for the mean path length claims,
 relying on Apple’s expert testimony that light condenses
 toward the center, therefore contradict its findings on the
 greatest curvature theory. See ’1536 Decision at *18.
 Masimo also criticizes the Board for relying on Apple’s ex-
 pert’s analysis of a single ray of light, rather than requiring
 an analysis of the aggregate effect on all light that travels
 through the convex surface or calculation of an average.
     Apple responds that Masimo forfeited any argument
 that dependent claims 12 and 14 of the ’265 patent were
 separately patentable by not arguing them before the
 Board. Apple also points to testimony and illustrations
 from its expert showing that the lens would concentrate
 light and reduce the mean path length, demonstrating that
 the Board’s finding was supported by substantial evidence.
     To the extent Masimo is making new criticisms of Ap-
 ple’s expert testimony (e.g., that he analyzed a single ray of
 light rather than the aggregate), we agree with Apple that
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 MASIMO CORPORATION v. APPLE INC.                            17



 those arguments should have been raised before the Board.
 However, Masimo could not have earlier argued that the
 Board’s findings were contradictory. We therefore do not
 determine that argument to be forfeited, despite Masimo’s
 previous decision to not separately argue for the independ-
 ent claims’ patentability.
      Nonetheless, we do not agree with Masimo on the mer-
 its. Although there may be tension between certain por-
 tions of testimony of Apple’s expert that the Board relied
 on, we do not observe a clear contradiction negating a find-
 ing of substantial evidence. That the greatest curvature
 theory may support increased light collection at the detec-
 tors is not incongruent with light being condensed toward
 the center. Those two theories are not mutually exclusive.
 See, e.g., ’1521 Decision at *20 (“[T]he light-focusing prop-
 erties of a convex lens . . . does not demonstrate ‘that a con-
 vex lens directs all light to the center.’”); Oral Arg. at
 15:10–20 (“Now, that motivation to combine does not focus
 on any sort of theory that all light must go to the dead cen-
 ter in a convex lens.”). The Board’s finding that light being
 condensed toward the center does not mean all light is con-
 centrated at a single point to the exclusion of light else-
 where is supported by substantial evidence. ’1521 Decision
 at *24 (“[I]t is reasonable to conclude, as Dr. Kenny does,
 that the central light lost by adding a protrusion will be
 outweighed by the peripheral light gained by adding a pro-
 trusion.”). The Board’s findings regarding claims 12 and
 14 of the ’265 patent were therefore supported by substan-
 tial evidence.
                               D
     Masimo argues that the Aizawa-Inokawa combination
 in the ’1520 and ’1521 IPRs does not disclose all the re-
 quired claim elements. Namely, the challenged claims all
 require a plurality of emitters and at least four detectors.
 See, e.g., ’265 patent, col. 45 ll. 4, 7. But Masimo contends
 that Inokawa discloses a sensor with two emitters and only
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 18                         MASIMO CORPORATION v. APPLE INC.




 one detector, while Aizawa discloses separate embodi-
 ments with either (1) multiple emitters and one detector,
 or (2) one emitter and multiple detectors. Masimo argues
 that the Board erred in relying on a person of ordinary skill
 in the art’s “ordinary creativity” to supply the allegedly
 missing limitation.
     Apple responds that the Board did not rely on a person
 of ordinary skill in the art’s “ordinary creativity” to supply
 any missing limitation. Rather, it asserts that the Board
 found the combination of Aizawa’s and Inokawa’s teach-
 ings would have rendered obvious a device meeting the
 claim limitations. Apple points out that nonobviousness is
 not established by attacking references individually when
 unpatentability is predicated upon a combination of prior
 art disclosures. See In re Merck & Co., Inc., 

 (Fed. Cir. 1986). Rather, obviousness concerns the
 combined teachings of the references. See 

 (“[T]he test
 is whether the references, taken as a whole, would have
 suggested appellant’s invention to one of ordinary skill in
 the [art].”).
     We agree with Apple that the Board properly consid-
 ered the combined teachings of the asserted references. As
 the Board found, “the combination of Aizawa and Inokawa
 teaches that having multiple emitters is beneficial, and
 having multiple detectors is beneficial.” ’1520 Decision at
 *14. And Aizawa describes its disclosed embodiments as
 nonlimiting examples. Aizawa at ¶ 32 (“The arrangement
 of the light emitting diode 21 and the photodetectors 22 is
 not limited to this.”); see also id. at ¶ 33 (explaining that
 “the same effect can be obtained” with a different arrange-
 ment). Crediting Apple’s expert testimony, the Board
 found that a person of ordinary skill in the art would have
 known and been motivated to use the four detectors dis-
 closed in Aizawa with the multiple emitters disclosed in
 both references. ’1520 Decision at *14. The Board’s finding
 on that issue was therefore supported by substantial evi-
 dence.
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 MASIMO CORPORATION v. APPLE INC.                               19



                                 E
     Masimo argues that the Board’s findings regarding de-
 pendent claims 11, 17, and 28 of the ’554 patent and de-
 pendent claims 12, 18, and 29 of the ’765 patent that recite
 specific protrusion height ranges were not supported by
 substantial evidence. Those claims specify a protrusion
 height of either “between 1 millimeter and 3 millimeters”
 or “greater than 2 millimeters and less than 3 millimeters.”
 See, e.g., ’554 patent, col. 45 l. 67, col. 46 l. 25. The specifi-
 cation explains that that height range “was found to help
 signal strength by about an order of magnitude versus
 other shapes.” Id. col. 20 ll. 18–22. Masimo points to the
 Board’s acknowledgement that “none of Aizawa, Inokawa,
 Ohsaki, or Mendelson-2006 teach the claimed range.”
 ’1539 Decision at *31; see also ’1715 Decision at *30. It goes
 on to criticize the Board for relying on the allegedly conclu-
 sory testimony of Apple’s expert, which largely cited diam-
 eter dimensions, rather than heights, and stated that there
 were a “a finite range of possible protruding heights” with-
 out specifically naming the heights. J.A. 37119, ¶¶ 275–76.
     Apple responds that, as the Board acknowledged, an
 express teaching is unnecessary when there are “a finite
 number of identified, predictable solutions” to a problem.
 See KSR Int’l Co. v. Teleflex Inc., 

 (2007);
 see also Uber Techs., Inc. v. X One, Inc., 

 (Fed. Cir. 2020). It argues that, as explained by its expert
 and found by the Board, there were limitations on the pro-
 trusion height due to user comfort and maximizing contact
 with the skin. Apple argues that it therefore did not matter
 that no particular reference identified its protrusion
 height, and that a person of ordinary skill in the art would
 have understood there to be only finite possibilities.
     The Board found that Apple “ha[d] shown sufficiently
 that only a finite number of solutions existed with respect
 to the height of a convex protrusion on a tissue-facing sen-
 sor, which would have met the art-recognized goals of both
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 20                        MASIMO CORPORATION v. APPLE INC.




 (1) intimate contact between the sensor’s surface and the
 user and (2) user comfort.” ’1539 Decision at *30. The
 Board credited Apple’s expert’s testimony that a person of
 ordinary skill in the art “would have found it obvious that
 a device designed to fit on a user’s wrist would be on the
 order of millimeters” given the practical limits on dimen-
 sions. 

 (quoting J.A. 37119, ¶ 275). It would have been
 preferable for Apple to identify the height options that
 meet these two goals with more specificity. However, in
 this case, which involves the mechanical arts, the identi-
 fied limitations on the range, which are supported by ex-
 pert testimony, provide sufficient guidance as to what a
 person of ordinary skill in the art would have understood
 the range of protrusion heights to be. And, as the Board
 found, Masimo never disputed Apple’s position that there
 was a finite number of options available for the height of a
 convex surface. See id. at *31. The Board’s findings re-
 garding claims 11, 17, and 28 of the ’554 patent and claims
 12, 18, and 29 of the ’765 patent were therefore supported
 by substantial evidence.
                              V
     Lastly, Masimo argues that the Board erred in holding
 that dependent claims 14–18 of the ’554 patent would have
 been obvious when it found that Apple had not shown that
 claim 13 (from which claims 14–18 depend) would have
 been. See ’1539 Decision at *1, 31. Generally, “dependent
 claims are nonobvious if the . . . claims from which they
 depend are nonobvious.” In re Fritch, 

 (Fed. Cir. 1992). Apple has not cross-appealed the Board’s
 finding regarding claim 13 and agrees that “[u]nder these
 circumstances, . . . the Board’s obviousness holding for
 claims 14–18 of the ’554 patent should be set aside.” Ap-
 pellee Br. at 72. We agree, and therefore reverse the
 Board’s finding that claims 14–18 of the ’554 patent would
 have been obvious.
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 MASIMO CORPORATION v. APPLE INC.                        21



                         CONCLUSION
     We have considered Masimo’s remaining arguments
 but find them unpersuasive. For the foregoing reasons, the
 decision of the Board is affirmed-in-part and reversed-in-
 part.
   AFFIRMED-IN-PART AND REVERSED-IN-PART.


                            COSTS
 Costs to Apple.