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`___________________
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`BEFORE THE PATENT TRIAL AND APPEAL BOARD
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`___________________
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`DECLARATION OF BRIAN W. ANTHONY, PH.D.
`IN SUPPORT OF PETITION FOR INTER PARTES REVIEW OF
`U.S. PATENT 8,886,269
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`i
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`Apple Inc.
`APL1003
`U.S. Patent No. 8,886,269
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`
`
`I.
`II.
`III.
`IV.
`V.
`
`VI.
`
`TABLE OF CONTENTS
`Introduction .................................................................................................. 1
`Qualifications ............................................................................................... 2
`My Understanding of Legal Principles ........................................................ 6
`Level of Ordinary Skill in the Art .............................................................11
`State of the Art ...........................................................................................12
`A. Non-invasive Optical Biosensors .........................................................12
`B. Photoplethysmography (PPG) ..............................................................15
`C. Artifacts and Non-invasive Optical Biosensors ...................................17
`D. Progression from Wired to Wireless Devices ......................................18
`The ’269 Patent ..........................................................................................20
`A. Overview of the ’269 Patent .................................................................20
`B. Summary of the Prosecution History ...................................................22
`Claim Construction ....................................................................................25
`VII.
`VIII. Overview of the Applied References .........................................................29
`A. Asada ....................................................................................................30
`B. Goodman ...............................................................................................35
`C. Hicks .....................................................................................................37
`D. Hannula .................................................................................................39
`E. Delonzor ...............................................................................................40
`F. Al-Ali ....................................................................................................41
`Ground 1: Asada Renders Claims 1, 2, 6, and 7 Obvious .........................43
`A. Asada Renders Independent Claim 1 Obvious .....................................44
`B. Asada Renders Claim 2 Obvious ..........................................................53
`C. Asada Renders Claim 6 Obvious ..........................................................53
`D. Asada Renders Claim 7 Obvious ..........................................................54
`Ground 2: The Combination of Asada and Hicks Renders Claim 3
`Obvious ......................................................................................................55
`A. Motivation for the Combination of Asada and Hicks ..........................55
`B. The Combination of Asada and Hicks Renders Claim 3 Obvious .......57
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`IX.
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`X.
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`XI.
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`XII.
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`Ground 3: The Combination of Asada and Hannula Renders Claims 4 and
`5 Obvious ...................................................................................................58
`A. Motivation for the Combination of Asada and Hannula ......................58
`B. The Combination of Asada and Hannula Renders Claim 4 Obvious ...60
`C. The Combination of Asada and Hannula Renders Claim 5 Obvious ...61
`Ground 4: The Combination of Asada and Delonzor Renders Claim 8
`Obvious ......................................................................................................65
`A. Motivation for the Combination of Asada and Delonzor .....................65
`B. The Combination of Asada and Delonzor Renders Claim 8 Obvious .66
`XIII. Ground 5: The Combination of Asada and Al-Ali Renders Claims 9 and
`10 Obvious .................................................................................................68
`A. Motivation for the Combination of Asada and Al-Ali .........................68
`B. The Combination of Asada and Al-Ali Renders Claim 9 Obvious ......70
`C. The Combination of Asada and Al-Ali Renders Claim 10 Obvious ....70
`XIV. Ground 6: Goodman Renders Claims 1 and 2 Obvious ............................71
`A. Goodman Renders Independent Claim 1 Obvious ...............................71
`B. Goodman Renders Claim 2 Obvious ....................................................81
`Ground 7: The Combination of Goodman and Hicks Renders Claim 3
`Obvious ......................................................................................................81
`A. Motivation for the Combination of Goodman and Hicks ....................81
`B. The Combination of Goodman and Hicks Renders Claim 3 Obvious .83
`XVI. Ground 8: The Combination of Goodman and Hannula Renders Claim 4
`Obvious ......................................................................................................84
`A. Motivation for the Combination of Goodman and Hannula ................84
`B. The Combination of Goodman and Hannula Renders Claim 4 Obvious
` 86
`XVII. Ground 9: The Combination of Goodman, Hannula, and Asada Renders
`Claim 5 Obvious ........................................................................................87
`A. Motivation for the Combination of Goodman, Hannula, and Asada ...87
`B. The Combination of Goodman, Hannula, and Asada Renders Claim 5
`Obvious .................................................................................................89
`XVIII. Ground 10: The Combination of Goodman and Asada Renders Claims 6
`and 7 Obvious ............................................................................................93
`- iii -
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`XV.
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`A. Motivation for the Combination of Goodman and Asada ....................93
`B. The Combination of Goodman and Asada Renders Claim 6 Obvious 94
`C. The Combination of Goodman and Asada Renders Claim 7 Obvious 95
`XIX. Ground 11: The Combination of Goodman and Delonzor Renders Claim 8
`Obvious ......................................................................................................96
`A. Motivation for the Combination of Goodman and Delonzor ...............96
`B. The Combination of Goodman and Delonzor Renders Claim 8 Obvious
` 98
`Ground 12: The Combination of Goodman and Al-Ali Renders Claims 9
`and 10 Obvious ........................................................................................100
`A. Motivation for the Combination of Goodman and Al-Ali .................100
`B. The Combination of Goodman and Al-Ali Renders Claim 9 Obvious
` 102
`C. The Combination of Goodman and Al-Ali Renders Claim 10 Obvious
` 103
`XXI. Conclusion ...............................................................................................103
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`XX.
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`I.
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`Introduction
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`I, Dr. Brian W. Anthony, declare as follows:
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`1.
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`I have been retained on behalf of Apple Inc. for the above-captioned
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`inter partes review proceeding to provide my expert opinions and expert
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`knowledge. I understand that this proceeding involves U.S. Patent No. 8,886,269
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`(“the ’269 patent”) titled “Wearable Light-Guiding Bands for Physiological
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`Monitoring” by Steven F. LeBoeuf, Jesse B. Tucker, and Michael E. Aumer, and
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`that the ’269 patent is currently assigned to Valencell, Inc.
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`2.
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`In preparing this declaration, I have reviewed and am familiar with all
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`the references cited herein. I have reviewed and am familiar with the ’269 patent
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`and its file history. I confirm that to the best of my knowledge the accompanying
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`exhibits are true and accurate copies of what they purport to be, and that an expert
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`in the field would reasonably rely on them to formulate opinions such as those set
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`forth in this declaration.
`
`3.
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`The ’269 patent describes non-invasive optical biosensors for health
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`monitoring. I am familiar with the technology described in the ’269 patent as of its
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`February 19, 2014 filing date and the state of the art as of its claimed February 25,
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`2009 priority date.
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`4.
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`I have been asked to provide my independent technical review,
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`analysis, insights, and opinions regarding the ’269 patent and the references that
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`form the basis for the grounds of rejection set forth in the Petition for Inter Partes
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`Review of the ’269 patent.
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`5.
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`I am being compensated at my rate of $350 per hour for my work on
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`this case. My compensation is not dependent upon my opinions or testimony or the
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`outcome of this case.
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`II. Qualifications
`As indicated in my curriculum vitae (“CV”), included as Exhibit
`6.
`
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`1004, I am currently a Principal Research Scientist at the Massachusetts Institute of
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`Technology (“MIT”). My CV
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`includes additional
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`information about my
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`professional history and contains further details on my experience, publications,
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`patents, and other qualifications to render an expert opinion. Herein, I highlight
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`experiences relevant to the technology of the patent at issue.
`
`7.
`
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`I earned a Bachelor of Science in Engineering from Carnegie Mellon
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`University in 1994 and a Master’s degree in Engineering from MIT in 1998. My
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`thesis topic related to anisotropic wave guides and acoustic non-destructive testing.
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`In 2006, I earned my Ph.D. in Engineering from MIT. My research focused on
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`high-performance computation, signal processing, and electro-mechanical system
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`design.
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`8.
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`In 1997, I co-founded Xcitex Inc., a company that specialized in
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`video-acquisition and motion-analysis software. I served as the Chief Technology
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`Officer and directed and managed product development until 2006. Our first demo-
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`product was an optical ring for human motion measurement used to capture user
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`hand motion in order to control the user’s interaction with a computer. Many of the
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`structural elements of our optical ring – developed more than a decade prior to the
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`’269 patent’s earliest possible priority date – addressed the same system issues as
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`those described and claimed in the ’269 patent. For example, our optical ring
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`included optical structures for light blocking, light redirection, and light capture.
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`We estimated human hand-motion based on how that motion changed the detected
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`light. In our application we did not try to eliminate motion artifact, we tried to
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`measure it. In developing our ring, we considered well-known problems such as
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`extraneous light and motion, which are, unsurprisingly, also discussed in the ’269
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`patent.
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`9.
`
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`I joined MIT in 2006 and have been the Director of the Master of
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`Engineering in Advance Manufacturing and Design Program for over ten years.
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`The degree program covers four main components–Manufacturing Physics,
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`Manufacturing Systems, Product Design, and Business Fundamentals. Many of the
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`courses, projects, and papers my students undertake involve technologies relevant
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`to the ’269 patent, for example, sensor devices including non-invasive optical
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`biosensors.
`
`10.
`
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`In 2011, I co-founded MIT’s Medical Electronic Device Realization
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`Center (“MEDRC”) and currently serve as co-director. The MEDRC aims to create
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`and deploy revolutionary medical technologies by collaborating with clinicians, the
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`microelectronics, and medical devices industries. We combine expertise in
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`computation; communications; optical, electrical, and ultrasound sensing
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`technologies; and consumer electronics. We focus on the usability and productivity
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`of medical devices using, for example, image and signal processing combined with
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`intelligent computer systems to enhance practitioners’ diagnostic intuition. Our
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`research portfolio includes low power integrated circuits and systems, big data,
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`micro electro-mechanical systems, bioelectronics, sensors, and microfluidics.
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`Specific areas of innovation include wearable, non-invasive and minimally
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`invasive optical biosensor devices, medical imaging, laboratory instrumentation,
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`and the data communication from these devices and instruments to healthcare
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`providers and caregivers. My experience with these devices is directly applicable
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`to the technology in the ’269 patent. For example, one current project related to
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`this work is in laser-ultrasound tomography. In this work, an eye and skin safe
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`pulsed laser beam is directed at the body and reflected and transmitted signals are
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`used to map internal tissue structures. In another current project, we use a patient-
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`mounted mobile near infrared (NIR) camera to image and characterize the surface
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`and subsurface structures of the skin.
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`
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` Furthermore, my research focuses on computational instrumentation, 11.
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`including the development of instrumentation and measurement solutions for
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`manufacturing systems and medical devices. Additionally, my teaching interests
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`include the design and modeling of large-scale systems in a wide variety of
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`decision-making domains and developing optimization algorithms and software for
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`analyzing and designing such systems. I teach or have taught courses in Electrical
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`Engineering, Controls, Optics, and Signal Processing, all pertinent subject matter
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`to the ’269 patent.
`
`12.
`
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`I also co-founded the Center for Polymer Micro-fabrication at MIT.
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`The Center’s research focuses on polymer-based manufacturing processes and the
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`large-scale commercialization of micro fluidic devices for chemical, biomedical,
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`and photonic applications. My experience under these initiatives is directly
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`applicable to the technology in the ’269 patent. We develop optical sensors to non-
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`invasively monitor soft flexible materials during the manufacturing process.
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`13.
`
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`I have published approximately 50 papers, and have received a
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`number of best paper and distinguished paper awards. I am a co-author of a
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`number of papers that relate to the technology in the ’269 patent, such as:
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`• Ranger, Bryan J.; Feigin, Micha; Pestrov, Nikita; Zhang, Xiang;
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`Lempitsky, Victor; Herr, Hugh M.; Anthony, Brian W., “Motion
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`compensation in a tomographic ultrasound imaging system:
`
`Toward volumetric scans of a limb for prosthetic socket design,”
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`- 5 -
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`2015 37th Annual International Conference of
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`the IEEE
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`Engineering in Medicine and Biology Society (EMBC), pp. 7204-
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`7207;
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`• Shih-Yu Sun, Matthew Gilbertson, and Brian W. Anthony, “Probe
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`Localization for Freehand 3D Ultrasound by Tracking Skin
`
`Features,” Book Section, Medical
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`Image Computing and
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`Computer-Assisted Intervention, MICCAI 2014, Springer, 2014,
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`Vol. 8674. Lecture Notes in Computer Science, pp. 365-372;
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`• J. H. Lee, C. M. Schoellhammer, G. Traverso, D. Blankschtein, R.
`
`Langer, K. E. Thomenius, D. S. Boning, B. W. Anthony, “Towards
`
`Wireless Capsule Endoscopic Ultrasound
`
`(WCEU),”
`
`IEEE
`
`International Ultrasonics Symposium (IUS), Chicago, IL, 2014, pp.
`
`734-737; and
`
`• Zakrzewski, A., Anthony, B. W., “Quantitative Elastography and
`
`its Application to Blood Pressure Estimation: Theoretical and
`
`Experimental Results,” 2013 IEEE Engineering in Medicine and
`
`Biology Society (EMBC), pp. 1136-1139.
`
`III. My Understanding of Legal Principles
`I understand that my analysis requires an understanding of the scope
`14.
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`of the ’269 patent claims and that the disclosures of the ’269 patent and the prior
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`art are judged from the perspective of a person of ordinary skill in the art at the
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`time of the purported invention. For the purposes of this declaration, I have been
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`instructed to consider the time of the purported invention of the ’269 patent to be
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`February 25, 2009, the earliest possible priority date for the ’269 patent. I note,
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`however, that my opinions would not change even if all the relevant disclosures
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`were judged from a later time period.
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`15.
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`I understand that during an inter partes review, claims of an unexpired
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`patent are to be given their broadest reasonable construction in light of the
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`specification as would be understood by a person of ordinary skill in the relevant
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`art. Unless otherwise noted, I have given the claim terms their plain and ordinary
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`meaning as understood by a person of ordinary skill in the art at the time of
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`purported invention.
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`16.
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`I understand that a claim is invalid if it is anticipated or obvious. I
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`understand that anticipation of a claim requires that every element of a claim is
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`expressly or inherently disclosed in a single prior art reference. I understand that an
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`anticipating reference need not use the exact terms of the claims, but must describe
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`the patented subject matter with sufficient clarity and detail to establish that the
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`claimed subject matter existed in the prior art and that such existence would be
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`recognized by persons of ordinary skill in the field of the purported invention. I
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`also understand that an anticipating reference must enable one of ordinary skill in
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`the art
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`to
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`reduce
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`the purported
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`invention
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`to practice without undue
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`experimentation.
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`17.
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`I understand that a patent claim is invalid if the claimed invention
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`would have been obvious to a person of ordinary skill in the art at the time of the
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`purported invention. This means that even if all of the requirements of the claim
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`cannot be found in a single prior art reference that would anticipate the claim, the
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`claim can still be invalid.
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`18.
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`I understand that an obviousness analysis involves comparing a claim
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`to the prior art to determine whether the claimed invention would have been
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`obvious to a person of ordinary skill in the art at the time of the purported
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`invention in view of the prior art and in light of the general knowledge in the art as
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`a whole. I also understand that obviousness is ultimately a legal conclusion based
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`on underlying facts of four general types, all of which must be considered: (1) the
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`scope and content of the prior art; (2) the level of ordinary skill in the art; (3) the
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`differences between the claimed invention and the prior art; and (4) any objective
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`indicia of nonobviousness.
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`19.
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`I also understand that obviousness may be established by combining
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`or modifying the teachings of the prior art. Specific teachings, suggestions, or
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`motivations to combine any first prior art reference with a second prior art
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`reference can be explicit or implicit, but must have existed before the date of
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`purported invention. I understand that prior art references themselves may be one
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`source of a specific teaching or suggestion to combine features of the prior art, but
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`that such suggestions or motivations to combine art may come from the knowledge
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`of a person of ordinary skill in the art. Specifically, a rationale to combine the
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`teachings of references may include logic or common sense available to a person
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`of ordinary skill in the art.
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`20.
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`I understand that a reference may be relied upon for all that it teaches,
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`including uses beyond its primary purpose. I understand that though a reference
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`may be said to teach away when a person of ordinary skill, upon reading the
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`reference, would be discouraged from following the path set out in the reference,
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`the mere disclosure of alternative designs does not teach away.
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`21.
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`I further understand that whether there is a reasonable expectation of
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`success from combining references in a particular way is also relevant to the
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`analysis. I understand there may be a number of rationales that may support a
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`conclusion of obviousness, including:
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`• Combining prior art elements according to known methods to yield
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`predictable results;
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`• Substitution of one known element for another to obtain predictable
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`results;
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`• Use of a known technique to improve similar devices (methods, or
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`products) in the same way;
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`• Applying a known technique to a known device (method, or product)
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`ready for improvement to yield predictable results;
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`• “Obvious to try” – choosing from a finite number of identified,
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`predictable solutions, with a reasonable expectation of success;
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`• Known work in one field of endeavor may prompt variations of it for use
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`in either the same field or a different one based on design incentives or
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`other market forces if the variations are predictable to one of ordinary
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`skill in the art; and
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`• Some teaching, suggestion, or motivation in the prior art that would have
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`led one of ordinary skill to modify the prior art reference or to combine
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`prior art teachings to arrive at the claimed invention.
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`22.
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`I understand that it is not proper to use hindsight to combine
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`references or elements of references to reconstruct the invention using the claims
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`as a guide. My analysis of the prior art is made from the perspective of a person of
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`ordinary skill in the art at the time of the purported invention.
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`23.
`
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`I understand that so-called objective considerations may be relevant to
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`the determination of whether a claim is obvious should the Patent Owner allege
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`such evidence. Such objective considerations can include evidence of commercial
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`success caused by an invention, evidence of a long-felt need that was solved by an
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`invention, evidence that others copied an invention, or evidence that an invention
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`achieved a surprising result. I understand that such evidence must have a nexus, or
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`causal relationship to the elements of a claim, in order to be relevant to the
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`obviousness or non-obviousness of the claim. I am unaware of any such objective
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`considerations having a nexus to the claims at issue in this proceeding.
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`24.
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`I understand that for a reference to be used to show that a claim is
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`obvious, the reference must be analogous art to the claimed invention. I understand
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`that a reference is analogous to the claimed invention if the reference is from the
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`same field of endeavor as the claimed invention, even if it addresses a different
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`problem, or if the reference is reasonably pertinent to the problem faced by the
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`inventor, even if it is not in the same field of endeavor as the claimed invention. I
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`understand that a reference is reasonably pertinent based on the problem faced by
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`the inventor as reflected in the specification, either explicitly or implicitly.
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`IV. Level of Ordinary Skill in the Art
`I understand that the person of ordinary skill in the art (“POSA”) is
`25.
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`viewed at the time of invention. For the purpose of this declaration, I have
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`evaluated the level of ordinary skill in the art as of February 25, 2009, the earliest
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`possible priority date for the ’269 patent. Based on the disclosure of the ’269
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`patent, it is my opinion that a POSA at the relevant time would have had at least a
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`four-year degree in electrical engineering, mechanical engineering, biomedical
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`engineering, optical engineering, or related field of study, or equivalent experience,
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`and at least two years’ experience in academia or industry studying or developing
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`physiological monitoring devices such as non-invasive optical biosensors. A
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`person of ordinary skill in the art would have also been familiar with, for example,
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`optical system design and signal processing. This description is approximate, and a
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`higher level of education or skill might make up for less experience, and vice-
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`versa.
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` Based on my knowledge, skill, and experience, I have an 26.
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`understanding of the capabilities of a person of ordinary skill in the relevant art.
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`For example, from my industry experience, I am familiar with what an engineer
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`designing non-invasive optical biosensors would have known and found
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`predictable in the art. From teaching and supervising my post-graduate students, I
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`also have an understanding of the knowledge that a person with this academic
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`experience possesses. Furthermore, I possessed the knowledge of a POSA myself
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`at least as of February 25, 2009.
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`V.
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`State of the Art
`A. Non-invasive Optical Biosensors
` The ’269 patent and the prior art references discussed herein are all 27.
`
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`from the field of non-invasive optical biosensors. These devices have a wide range
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`of applications, for example, measuring blood flow characteristics such as blood
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`oxygen saturation, blood pressure, and cardiac output. Non-invasive optical
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`biosensors are generally characterized as devices that pass light from a light source
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`through the skin (i.e., non-invasive) into a blood perfused area of body tissue and
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`then use a photodetector to sense the absorption of light in the tissue. (APL1001,
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`4:1-3; APL1005, p. 28; APL1006, 1:11-17; APL1007, 1:20-40; APL1008, 1:10-25;
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`APL1009, 1:9-27; APL1010, 1:9-20; APL1011, ¶4.)
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`
`
` Non-invasive optical biosensors can take various form factors, for 28.
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`example, flat sensors, wraps, clamps, or rings. (APL1005, p. 34; APL1006, 5:14-
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`23; APL1007, 4:30-37; APL1011, ¶34; APL1013, p. 8; APL1014, p. 407;
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`APL1015, p. 913; APL1016, 3:42-46, Figures 1A-1B, 24.) One common and well-
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`understood non-invasive optical biosensor is a pulse oximeter, which is described
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`in an embodiment of the ’269 patent. (See e.g., APL1001, 23:1-23.) Pulse
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`oximeters have been known since at least the 1970’s, with technology used in
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`pulse oximeters dating back to the 1930’s. (APL1017, p. 98.) Pulse oximetry is a
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`widely used method for monitoring arterial hemoglobin oxygen saturation (SpO2).
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`(APL1005, p. 50; APL1006, 1:11-17; APL1007, 1:34-40; APL1017, p. 98.)
`
`
`
` The system components of non-invasive optical biosensors, like pulse 29.
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`oximeters, have been rather customary for decades. Typical components include:
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`one or more electrically controlled optical light-sources; mechanical and optical
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`elements to guide and focus the light into the body; mechanical and optical
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`elements to control light within the sensing device; mechanical and optical
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`elements to capture and focus the light leaving the body; light detector(s) that
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`generate an electrical signal proportional to the intensity of received light;
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`processor(s) to control the light source; and processor(s) to analyze the electrical
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`signals. For example, a pulse oximeter described by Mendelson in 1991, shown
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`below, included multiple LEDs, multiple photodiodes, an optical shield, and an
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`optically clear epoxy, mounted on a silicon rubber base. (APL1013, p. 8, Figure 1.)
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`
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` Other well-known components 30.
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`include optical or mechanical
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`components to block or capture-and-divert stray internal and ambient light;
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`mechanical elements to firmly and comfortably affix the device to a selected
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`location on the body; and sub-systems (e.g., sensors and algorithms) to measure
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`and compensate for motion. (APL1005, pp. 31-33 (motion/noise algorithms);
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`APL1006, 5:28-31 (sensor adhesively fastened to skin); APL1009, 2:58-66, 4:46-
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`53 (reflective and opaque materials to redirect and block light).)
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` Another example, U.S. Patent No. 5,226,417 to Swedlow et al., filed
`31.
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`in 1991, describes a layered non-invasive optical biosensor that is wrapped around
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`a finger. Swedlow discloses a number of typical components found in non-invasive
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`optical biosensors, including: an outer layer or covering (bandage layer 21); optical
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`emitters (LEDs 13, 16); an optical detector (photodetector 15); a light transmissive
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`layer protecting the optical components (clear polyethylene layer 12); and a light-
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`blocking or “cladding” layer (opaque white polypropylene layer 14) with holes for
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`the optical components. (APL1006, 5:42-51, 5:66-68, Figure 2.)
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`B. Photoplethysmography (PPG)
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`
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` Photoplethysmography (PPG) is an optical technique used by many 32.
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`non-invasive optical biosensors, like pulse oximeters, to detect blood flow
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`characteristics such as blood volume changes in a microvascular bed of tissue. (See
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`e.g., APL1013, p. 7.) The technique relies on a PPG sensor to detect a PPG signal
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`produced by variations in the quantity of arterial blood associated with periodic
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`cardiac contraction and relaxation. (APL1013, p. 8.) The PPG signal has pulsatile
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`(AC) components attributed to changes in the blood volume synchronous with each
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`heartbeat and is superimposed on a low frequency (DC) baseline with variation
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`from respiration, sympathetic nervous system activity, and thermoregulation.
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`(APL1017, p. 101.) The ’269 patent repeatedly highlights the use of PPG in
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`embodiments of the disclosed sensor devices. (APL1001, 3:65-4:3, 11:34-36,
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`13:33-36, 20:48-55, 21:12-23, 23:5-8, 26:21-29.)
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`
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` Using PPG, blood flow characteristics like SpO2 values can be 33.
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`derived from an empirically calibrated function. For example, the time-varying
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`(AC) signal component of the PPG at each wavelength can be divided by the
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`corresponding time-invariant (DC) component which is due to light absorption and
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`scattering by bloodless tissue, residual arterial blood volume during diastole, and
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`non-pulsatile venous blood. (APL1017, p. 101.)
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`
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` PPG measurements can be performed in either transmission (also 34.
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`called transmittal or transmittance) or reflection modes. (APL1013, pp. 7-8;
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`APL1014, p. 405; APL1015, p. 912.) A POSA would have been familiar with both
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`of these modes and understood that components of devices used primarily for one
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`mode could be adapted for use with the other mode. (APL1013, p. 8; APL1010,
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`3:53-58.) In transmission mode, the sensor is usually attached across a body part,
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`for example, a fingertip or earlobe, so that the LED(s) and photodetector are placed
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`on opposite sides of a pulsating vascular bed. (APL1014, pp. 403, 405; APL1015,
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`- 16 -
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`
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`p. 912.) In transmission mode, light emitted from the LED(s) is diffused by the
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`skin and subcutaneous tissues predominantly in a forward-scattering direction. In
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`reflection mode, the LED(s) and photodetector are both mounted facing the same
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`side of the vascular bed. (APL1013, p. 8; APL1014, p. 405; APL1015, p. 912.) In
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`reflection mode, only a small fraction of the incident light is backscattered by the
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`subcutaneous layers. (APL1015, p. 914.) The backscattered light intensity reaching
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`the skin surface is typically distributed over a relatively large area surrounding the
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`LEDs. (Id.) Hence, the design of a reflectance-mode often includes a sensor that
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`has improved sensitivity to detect sufficiently strong PPG signals from the body
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`combined with sophisticated digital signal processing algorithms to process the
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`relatively weak and often noisy signals. (APL1013, p. 8.)
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`C. Artifacts and Non-invasive Optical Biosensors
` Sources of error and artifacts for non-invasive optical biosensors, for 35.
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`example, associated with the PPG technique, have been known since the technique
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`was first used. Artifact has three major sources: ambient light, low perfusion, and
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`motion, which all lead to poor signal-to-noise ratio. (APL1017, p. 103; APL1013,
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`p. 8; APL1014, p. 405; APL1005, p. 30; APL1006, 1:5-10, 3:6-16; APL1007,
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`3:56-62; APL1008, 2:42-45.) It has been long recognized that noise sources such
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`as stray and ambient light and movement of the subject corrupt the information that
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`is obtained from non-invasive optical biosensors. Motion artifacts arise from
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`kinematic or mechanical forces, changes in the coupling of the sensor to the
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`subject, local variation in patient anatomy, optical properties of tissue due to
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`geometric realignment or compression, or combinations of these effects.
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`
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` Multiple ways to compensate for these artifacts were well understood 36.
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`before 2009. Examples include:
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`• mechanical elements–for example, adhesives
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`to reduce sensor
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`movement (APL1006, 5:28-36; APL1007, 4:59-5:2);
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`• optical elements–for example, shielding materials (APL1013, p. 8;
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`APL1014, pp. 406-407; APL1005, pp. 34-35; APL1007, 9:11-16);
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`• system design–for example, component location (APL1005, p. 30;
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`APL1013, p. 8; APL1014, p. 405); and
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`• signal processing techniques–for example, removing the artifact by
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`generating two independent measurements with two light sources or
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`detectors and performing a subtraction, or through signal averaging
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`(APL1005, pp. 31-33; APL1017, p. 101; APL1014, pp. 404-405).
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`D. Progression from Wired to Wireless Devices
` Like many other technologies, a nascent transition in interest fr