as) United States
`a2) Patent Application Publication 0) Pub. No.: US 2013/0267854 Al
`
` Johnsonet al. (43) Pub. Date: Oct. 10, 2013
`
`
`US 20130267854A1
`
`(54) OPTICAL MONITORING AND COMPUTING
`DEVICES AND METHODSOF USE
`
`(57)
`
`ABSTRACT
`
`(76)
`
`Inventors: Jami Johnson, Boise, ID (US); Michelle
`Sabick, Boise, ID (US)
`
`(21) Appl. No.: 13/442,551
`
`(22)
`
`Filed:
`
`Apr. 9, 2012
`
`Publication Classification
`
`(51)
`
`Int. Cl.
`A6IB 5/00
`(52) U.S.CL.
`CPC viceccscsssetesseseecetetensees A61B 5/0082 (2013.01)
`USPC vice eeeeestesteeteseeceeceecneseee 600/473; 600/479
`
`(2006.01)
`
`Thepresentinvention relates to medical devices and,in par-
`ticular, to optical computing devices configured to monitor
`cardiac-related conditions. One optical computing device
`includesa substrate, at least one light source mounted on the
`substrate and configured to emit electromagnetic radiation
`that optically interacts with a vasculature and generates an
`optically interacted signal, a plurality of detectors mounted
`on the substrate and configured to detect the optically inter-
`acted signal, and a stabilizing matrix arranged on the sub-
`strate and substantially surrounding the at least one light
`source andthe plurality of detectors. The stabilizing matrix
`may be configured to absorb vibration and thereby reduce
`motion artifacts detectable by the plurality of detectors.
`
` 1
`
`APPLE 1068
`Apple v. Masimo
`IPR2022-01291
`
`1
`
`APPLE 1068
`Apple v. Masimo
`IPR2022-01291
`
`

`

`Patent Application Publication
`
`Oct. 10, 2013 Sheet 1 of 3
`
`US 2013/0267854 Al
`
`°
`
`
`
`8 eS
`Fd
`a
`
`“eot
`
`i
`
`
`NN
`iq4h
`
`ttL
`
`oi
`y
`108:
`Tas
`
`«
`
`jog
`
`298
`
`agg
`
`202
`
`agg
`
`266
`
`204
`
`\402
`
`FIG. 2a
`
`460
`
`106
`
`298
`
`agg
`
`78?
`
`agg
`
`206
`
`204
`
`102
`
`FiG. 2b
`
`106
`Nae
`
`jog
`
`208
`
`49g
`
`202
`
`406
`
`S06
`
`204
`
`102
`
`FIG. 2c
`
`2
`
`

`

`Patent Application Publication
`
`Oct. 10, 2013 Sheet 2 of 3
`
`US 2013/0267854 Al
`
`
`
`3
`
`

`

`Patent Application Publication
`
`Oct. 10, 2013 Sheet 3 of 3
`
`US 2013/0267854 Al
`
`400
`
`FIG. 4
`
`4
`
`

`

`US 2013/0267854 Al
`
`Oct. 10, 2013
`
`OPTICAL MONITORING AND COMPUTING
`DEVICES AND METHODS OF USE
`
`BACKGROUND
`
`[0001] The present invention relates to medical devices
`and, in particular, to optical computing devices configured to
`monitor cardiac-related conditions.
`
`Photoplethysmography (PPG)is a noninvasive and
`[0002]
`low cost optical technique used for studying skin blood vol-
`umepulsations. Blood-pressure waves that are generated by
`the heart propagate along the skin arteries, locally increasing
`and decreasing the tissue blood volumewiththe periodicity of
`heartbeats. PPG exploits this phenomenon through the use of
`narrow-bandlight-emitting diodes (LEDs)in the infrared or
`near-infrared region. Back scattering of the optical radiation
`is typically detected in either transmission or reflection con-
`figuration by one or morestrategically-placed photodetec-
`tors. Heart rate, respiratory rate, and tissue blood perfusion,
`as well as indicators of cardiac disorders and peripheral vas-
`cular diseases can be extracted from the analysis of a single
`PPG trace. Factors such as skin color, volume of adipose
`tissue, ambientlight, sensor location, and movementartifacts
`have been knownto affect the robustness and consistency of
`PPGsignals.
`[0003]
`Oflate, there has been a resurgence of interest in
`using PPG, driven primarily by the demand for low cost,
`simple, and portable technology for the primary care and
`community-basedclinical settings, and the wide availability
`of inexpensive and small semiconductor components. PPG
`technology has been used in a wide range of commercially
`available medical devices for measuring oxygen saturation,
`blood pressure and cardiac output, assessing autonomic func-
`tion, and also detecting peripheral vascular disease. As a
`result, innovative methods or devices capable of obtaining
`reliable PPG signals in various locations on the body have the
`potential to be useful in variousclinical applications, as well
`as for self-monitoring applications.
`
`SUMMARYOF THE INVENTION
`
`mounted on the front side of the substrate and configured to
`detect the optically interacted signal. The device may further
`include a stabilizing matrix arranged on the front side of the
`substrate and substantially surroundingthe at least one light
`source andthe plurality of detectors. The stabilizing matrix
`may be configured to absorb vibration and thereby reduce
`motion artifacts detectable by the plurality of detectors.
`[0007]
`In some aspects of the disclosure, a method for
`detecting cardiac-related conditionsis disclosed. The method
`may include emitting electromagnetic radiation through a
`vasculature using at least one light source mounted on a
`substrate. The electromagnetic radiation may be configured
`to optically react with the vasculature andreflect an optically
`interacted signal. The method mayalso include detecting the
`optically interacted signal with a plurality of detectors
`mounted on the substrate. The plurality of detectors may be
`configured to generate signal data. The method may further
`include absorbing vibration and reducing motion artifacts
`detectable by the plurality of detectors with a stabilizing
`matrix, where the stabilizing matrix may be arranged on the
`substrate and substantially surroundingthe at least one light
`source and the plurality of detectors. The method may even
`further include receiving the signal data with a processing
`device communicably coupled to the plurality of detectors,
`and processing the signal data to determine the cardiac-re-
`lated conditions.
`
`[0008] The features and advantagesofthe present invention
`will be readily apparent to those skilled in the art upon a
`reading of the description of the preferred embodimentsthat
`follows.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0009] The following figures are includedto illustrate cer-
`tain aspects ofthe present invention, and should not be viewed
`as exclusive embodiments. The subject matter disclosed is
`capable of considerable modifications, alterations, combina-
`tions, and equivalents in form and function, as will occur to
`those skilled in the art and having the benefit of this disclo-
`sure.
`
`FIG. 1a is an exemplary optical computing device,
`[0010]
`[0004] The present invention relates to medical devices
`according to one or more embodimentsdisclosed.
`and, in particular, to optical computing devices configured to
`
`[0011] FIG. 161savariation of the exemplary optical com-
`monitor cardiac-related conditions.
`puting device of FIG. 1a, according to one or more embodi-
`ments disclosed.
`
`In some aspects of the disclosure, a device is dis-
`[0005]
`closed. The device may include a substrate and at least one
`light source mounted on the substrate and configured to emit
`electromagnetic radiation that optically interacts with a vas-
`culature and generates an optically interacted signal. The
`device mayalso include a plurality of detectors mounted on
`the substrate and configuredto detect the optically interacted
`signal, and a stabilizing matrix arranged on the substrate and
`substantially surroundingthe atleast onelight source and the
`plurality of detectors. The stabilizing matrix may be config-
`ured to absorb vibration and thereby reduce motionartifacts
`FIG.3c illustrates the optical computing device of
`[0015]
`detectable by the plurality of detectors.
`FIG.36 havingastabilizing matrix applied thereto, according
`to one or more embodiments disclosed.
`[0006]
`In some aspects, another device may be disclosed.
`The device may include a housing havinga front surface and
`a back surface, and a substrate having a front side and a back
`side, where the back side may be removably coupledto the
`back surface of the housing. The device may also include at
`least one light source mounted on the front side of the sub-
`strate and configured to emit electromagnetic radiation that
`optically interacts with a vasculature and thereby generates an
`optically interacted signal. A plurality of detectors may be
`
`FIGS. 2a, 2d, and 2c are side views ofthe exemplary
`[0012]
`optical computing device of FIG. 1, according to one or more
`embodiments disclosed.
`
`FIG. 3a is an isometric view of an exemplary hous-
`[0013]
`ing that may be usedto receive andseat an optical computing
`device, according to one or more embodiments disclosed.
`[0014]
`FIG. 34 illustrates the housing of FIG. 3@ with an
`optical computing device arranged therein, according to one
`or more embodiments disclosed.
`
`FIG. 4 illustrates an exemplary interface configured
`[0016]
`to providereal-time cardiac-related information, according to
`one or more embodiments.
`
`DETAILED DESCRIPTION
`
`[0017] The present invention relates to medical devices
`and, in particular, to optical computing devices configured to
`
`5
`
`

`

`US 2013/0267854 Al
`
`Oct. 10, 2013
`
`monitor cardiac-related conditions. The various embodi-
`ments disclosed herein may be used in a variety of applica-
`tions and in a variety of ways in order to detect, monitor,
`and/or report a range of cardiac-related conditions. For
`example, the disclosed optical computing devices may be
`useful for, but not limited to, determining oxygen concentra-
`tion in blood vessels, determining an individual’s bloodpres-
`sure and/or heart rate, determining the general condition of
`the adjacent vasculature of an individual, determining calorie
`expenditure based on respiration, determining the general
`condition ofheart valves in an individual, and determining an
`individual’s base metabolic rate. The resulting output signal
`may be depicted in the form ofa photoplethysmograph (PPG)
`trace that can be analyzed. Thoseskilled in the art will readily
`recognize additional useful applications for the optical com-
`puting devices, and several advantages that may be derived
`from the novel components and configurations discussed
`herein.
`
`[0018] Referring now to FIG. 1a, illustrated is an exem-
`plary optical computing device 100, according to one or more
`embodiments. In at least one embodiment, the device 100
`may be generally characterized as a pulse oximeter, a pho-
`toplethysmograph, or similarly configured optoanalytical
`device. The optical computing device 100 may include a
`generally planar substrate 102 andat least one light source
`104 mounted thereon or otherwise coupled thereto. The sub-
`strate 102 may be made of any rigid or semi-rigid material
`used to mechanically support and electrically connect the
`various componentsof the device 100. For example, the sub-
`strate 102 may be made of, but is not limited to, polymers,
`plastics, elastomers, metals, ceramics, combinations thereof,
`or the like. In some embodiments, the substrate 102 maybe a
`printed circuit board. In other embodiments, however, the
`substrate 102 may be madeofa flexible material so as to be
`able to generally conform to the contours or shape of the
`location on the body wherethe optical computing device 100
`is utilized. Moreover, it should be noted that while FIG. la
`illustrates the substrate 102 in a generally circular shape,
`other shapes are also contemplated herein. For example, the
`substrate 102 may exhibit an oval, elliptical, or any suitable
`polygonal shape. In at least one embodiment, the substrate
`102 may be octagonal.
`[0019] The light source 104 may be any device capable of
`emitting or generating electromagnetic radiation. As used
`herein, the term “electromagnetic radiation”refers to visible
`light, ultravioletlight, red, infrared and near-infrared radia-
`tion, radio waves, microwave radiation, X-ray radiation and
`gammaray radiation. In some embodiments, the light source
`104 maybea light bulb, a light emitting device (LED), a laser,
`aphotonic crystal, an X-Ray source,orthe like. In at least one
`embodiment,the light source 104 may be an LED configured
`to emit red light (i.e., light having a wavelength between
`about 620 nm and about 740 nm) and/orinfrared light(1.e.,
`light having a wavelength between about 750 nm and about 1
`mm). After being emitted from the light source 104, the
`electromagnetic radiation optically interacts with,
`for
`example, the vasculature of the individual and reflects an
`optically interacted signal. As used herein, “vasculature”
`means the circulatory system for passing nutrients, gases,
`hormones, blood cells, etc. to and from cells in order to
`maintain bodily homeostasis.
`[0020] As illustrated, the light source 104 maybe centrally-
`located on the substrate 102. In other embodiments, however,
`the light source 104 maybe arrangedat other locations on the
`
`surface ofthe substrate 102, without departing from the scope
`of the disclosure. As shown in FIG.16, the device 100 may
`equally include more than one light source 104, illustrated
`therein as light sources 104a and 1048. In one embodiment,
`the light sources 104a,b may be centrally-located on the
`substrate 102, as depicted. In other embodiments, however,
`the light sources 104a,6 may be arranged in otherrelative
`configurations, without departing from the scope of the dis-
`closure. Two or more light sources 104a,5 may allow for the
`comparison of electromagnetic radiation absorptionat differ-
`ent wavelengths. For example, thefirst light source 104a may
`emit infrared light and the secondlight source 1045 may emit
`red light in order to measure the difference in absorption of
`oxy- and deoxygenated hemoglobin, respectively, which can
`be used to calculate oxygen saturation. In one embodiment,
`the light sources 104a,5 may be configured to alternatingly
`turn on/off (1.e., pulsed) such that the detectors 106 are able to
`detect and measure the respective absorption rates. In other
`embodiments, however, one or moreofthe detectors 106 may
`be configured to detect wavelengths of infrared light while
`other detectors 106 are configured to detect wavelengths of
`red light in order to distinguish between the two signals.
`Potential other parameters that may be measured with two
`light sources 104a,6 or varied detectors 106 include lipid
`plaque,fat, collagen, water, glucose, and elastin. Also, some
`colors may obtain a better signal dependingonthe individual.
`As can be appreciated, such alternative embodiments may be
`optimized for many physiological variables.
`[0021] The device 100 may further include one or more
`detectors 106 mounted on the substrate 102 or otherwise
`coupled thereto. The detectors 106 may be optical detectors
`configured to detect the optically interacted signal reflected
`from the vasculature of an individual. Suitable detectors 106
`
`for the device 100 mayinclude, but are not limited to, pho-
`totransistors, photodiodes, photoresistors, photomultiplier
`tubes, photovoltaic cells, optical nanosensors, combinations
`thereof, or the like.
`[0022]
`Asillustrated, the detectors 106 may be configured
`to form a circular array about the light source 104. Since
`reflected light tendsto scatter ina circular pattern, the circular
`array of detectors 106 may prove advantageousin enlarging
`the detection area of the device 100 and therefore increasing
`the probability of detecting a reflected signal. In other
`embodiments, however, the detectors 106 may be arranged in
`any other geometric configuration or arrangementso long as
`the light source 104 generally remains centrally-located with
`respect to the detectors 106. For example, the detectors 106
`mayequally be arranged in various polygonal configurations
`(e.g., square, rectangular, octagonal, etc.) and likewise pro-
`vide adequate detection. Moreover, while FIGS. 1a and 1b
`depict the detectors 106 as being equidistantly offset from
`each other circumferentially, embodiments are contemplated
`herein where the detectors 106 are randomly offset from each
`other or otherwise arrangedin a predetermined, non-equidis-
`tant fashion.
`
`[0023] The detectors 106 may beradially-offset from the
`light source 104 by a predetermined distance 107. As can be
`appreciated, however, the predetermined distance 107 may be
`altered in varying embodiments of the device 100 in order to
`achieve desired reflectance parameters between the light
`source 104 and the detectors 106. For example, optical scat-
`tering may vary amongindividuals dueto skin color, volume
`ofadiposetissue, age, thickness of skin,location ofthe device
`100 on the body, etc. Consequently, the predetermined dis-
`
`6
`
`

`

`US 2013/0267854 Al
`
`Oct. 10, 2013
`
`tance 107 may be optimized in order to detect the best signal
`for a particular individual. Moreover, whereasa total of eight
`detectors 106 are illustrated in FIGS. 1¢ and 10 inthe array,
`embodiments contemplated herein may include moreorless
`than eight detectors 106 in an array, without departing from
`the scopeofthe disclosure. Moreover,in at least one embodi-
`ment, a second array (not shown) of detectors 106 may be
`included in the device 100 and be radially-offset fromthefirst
`array of detectors 106. The second array may be used to
`supplementthefirst array of detectors 106 and thereby pro-
`vide a more accurate resulting detection.
`[0024] The device 100 may further include a power supply
`108 and a processing device 110 (shown in phantom). In one
`embodiment, the power supply 108 and processing device
`110 may each be arranged or otherwise mounted on the
`opposing side of the substrate 102 so as to not interfere with
`the communication between the light source 104 and detec-
`tors 106. The powersupply 108 may be configured to provide
`power to the light source 104, the detectors 106, and the
`processing device 110 in order to properly operate the device
`100. In one embodiment, the power supply 108 may include
`one or more rechargeable batteries, or the like. In other
`embodiments, however, the power supply 108 may be con-
`figured as an energy-scavenging device powered by kinetic
`energy derived from movementofthe individual wearing the
`device 100. For example, movement of the individual may
`cause a magnetin an electromagnetic generator to move and
`thereby generate a rate ofchange offlux which results in some
`induced emf on adjacent coils, thereby generating a power
`output. The processing device 110 may be communicably
`coupledto eachofthe detectors 106 and configured to process
`the signal data received therefrom and thereafter provide an
`output for consideration by the user.
`[0025]
`In some embodiments, the processing device 110
`may be, for example, a general purpose microprocessor, a
`microcontroller, a digital signal processor, an application spe-
`cific integrated circuit, a field programmable gate array, a
`programmable logic device, a controller, a state machine, a
`gated logic, discrete hardware components,an artificial neu-
`ral network,or any like suitable entity that can perform cal-
`culations or other manipulations of data. In some embodi-
`ments, computer hardware can include elements such as, for
`example, a memory (e.g., random access memory (RAM),
`flash memory, read only memory (ROM), programmable read
`only memory (PROM),
`erasable read only memory
`(EPROM)), or any other like suitable storage device or
`medium. Executable sequences can be implemented with one
`or more sequencesof code contained in the memory.In some
`embodiments, such code can be read into the memory from
`another machine-readable medium, such as a computer com-
`municably coupled (either wired or wirelessly) to the pro-
`cessing device 110. As used herein, a machine-readable
`medium will refer to any medium that directly or indirectly
`provides instructions to a processor for execution.
`[0026] Execution of the sequences of instructions con-
`tained in the memorycan cause the processing device 110 to
`perform the process steps described herein.In addition, hard-
`wiredcircuitry can be usedin place of or in combination with
`software instructions to implement various embodiments
`described herein. Thus, the present embodiments are not lim-
`ited to any specific combination ofhardware and/or software.
`[0027]
`In other embodiments, the processing device 110
`mayinstead bea wireless transmitter communicably coupled
`to the detectors 106 and configured to wirelessly communi-
`
`cate (e.g., via BLUETOOTH®technology or the like) the
`signal data received from the detectors 106 to an adjacent
`computing device adaptedto filter and analyzethe signal data
`and display any resulting cardiac-related data (e.g., a PPG
`trace). The adjacent computing device, such as a computer,
`personaldigital assistant (PDA), smartphone,or the like, may
`be configured to receive and process the data received from
`the wireless transmitter and provide an output for consider-
`ation by the user. The smartphone, for example, may include
`an “app” which could be configured to process the received
`signals automatically. In other embodiments, however, one or
`more ports 112 may be defined on or otherwise provided by
`the device 100 in orderto allow a wired connection directly to
`the adjacent computing device. In at least one embodiment,
`the ports 112 may furtherbe utilized to provide powerto the
`device 100, such as for recharging the power supply 108.
`
`[0028] Referring now to FIGS. 2a, 26, and 2c, with contin-
`ued reference to FIGS. 1a and 14,illustrated are a series of
`side viewsofthe optical computing device 100. As depicted,
`the device 100 may include a front side 204 and a back side
`206, where the detectors 106 and otherelectrical components
`are arranged on the front side 204. The device 100 mayfurther
`include a stabilizing matrix 202 applied to or otherwise
`arranged on thefrontside 204 ofthe substrate 102 and thereby
`provide an outer surface 208. In some embodiments, the
`stabilizing matrix 202 may substantially surround or other-
`wise cover the various electrical components of the device
`100, such as the detectors 106 and the light source 104 (not
`shown). In other embodiments, however,
`the stabilizing
`matrix 202 may be configured to surround the components,
`but the detectors 106 and/orthe light source 104 may protrude
`a short distance past the outer surface 208 of the stabilizing
`matrix 202. For example, in FIG. 2a, the outer surface 208 of
`the stabilizing matrix 202 is illustrated as being flush with the
`detectors 106; in FIG. 24,the stabilizing matrix 202is illus-
`trated as substantially covering the detectors 106; andin FIG.
`2c, the detectors 106 protrude a short distance past the outer
`surface 208 ofthe stabilizing matrix 202. In FIG.28,it will be
`appreciated that the stabilizing matrix 202 may be hollowed
`out or otherwise removed directly above each detector 106
`(and the light source 104) such that adequate reflected elec-
`tromagnetic radiation is able to impinge upon each detector
`106. This is shown in more detail below in FIG.3c.
`
`[0029] The stabilizing matrix 202 may be configuredto be
`in direct contact with or substantially adjacent to the skin of
`the individual whenthe device 100 is in use. In operation,the
`stabilizing matrix 202 not only protects the light source 104
`and detectors 106 from moisture and environmental contami-
`
`nants, but it may also be configuredto reducevibrationeffects
`that would otherwise compromise the resulting PPG signal
`provided by the device 100. Motionartifacts can be particu-
`larly damaging to optoanalytical devices, such as the device
`100 disclosed herein. The stabilizing matrix 202 may be
`configured to absorb all or a portion of these motionartifacts
`by reducing the motion ofthe detectors 106 with respect to the
`skin of the individual. To accomplish this, the stabilizing
`matrix 202 may be madeof a pliant material. For example,in
`one embodiment,the stabilizing matrix 202 may be made of
`silicone or a typeofsilicone. In other embodiments, however,
`the stabilizing matrix may be made ofother pliant materials
`such as, but not limited to, polymers (e.g., urethanes, etc.),
`elastomers (e.g., rubber, ethylene-vinyl acetate, etc.), soft
`plastics, foams, combinationsthereof, or the like.
`
`7
`
`

`

`US 2013/0267854 Al
`
`Oct. 10, 2013
`
`[0030] The stabilizing matrix 202 not only contributes to
`the reduction of motion artifacts, but may also serve to sub-
`stantially seal off the detectors 106 from ambientlight inter-
`ference, which could likewise have a detrimental effect on the
`resulting PPG signal. To facilitate this, in some embodiments,
`the stabilizing matrix 202 may be madeof a generally trans-
`lucent or opaque material. It will be appreciated, however,
`that embodiments are nonetheless contemplated herein where
`the stabilizing matrix 202 is made of a generally transparent
`material. With a translucent or opaque material, however,
`external interferent light may be absorbedbythestabilizing
`matrix 202 instead of passing therethrough and thereafter
`impinging upon the detectors 106. To further seal off the
`detectors 106 from ambientlight interference, one or more
`opticalfilters or films (not shown) maybe appliedto the outer
`surface 208 of the stabilizing matrix 202. In at least one
`embodiment,the opticalfilters or films may be arranged only
`overthe detectors 106. As will be appreciated by those skilled
`in the art, optical filters and/orfilms maybe usefulin filtering
`out unwanted external light signals.
`[0031]
`In operation,
`the device 100 may be used, for
`example, as a heart monitor, wherethe interaction ofthe light
`source 104 with the detectors 106 is configured to detect or
`otherwise record a heartbeat of an individual. To accomplish
`this, the device 100 may be arranged to measure the vascula-
`ture of an individual, and specifically the locally increasing
`and decreasing tissue blood volumethat correspondsto the
`periodicity ofheartbeats. Accordingly, the device 100 may be
`generally placed at locations on the body wherea heartbeatis
`moreapt to be detected. For example, the device 100 may be
`placedat the calf, the upper arm,the ankle, toes, fingers, the
`forehead, the chest, or any other suitable location on the body
`of the individual.
`
`In at least one embodiment, the device 100 may be
`[0032]
`arranged on the wrist ofthe individual, either on the top or the
`underside of the wrist. To facilitate this, the device 100 may
`be used in conjunction with a commercially-available wrist-
`watchorthe like. For example, the device 100 may be coupled
`to the back-side of a wristwatch such that the device 100, and
`in particularthe stabilizing matrix 202, is directed toward and
`in direct contact with the skin of the individual. The device
`
`100 may be removably coupled to the watch using, for
`example, adhesives, mechanical fasteners, VELCRO®, mag-
`netic attraction, suction devices, combinations thereof, or the
`like as applied to the back side 206 of the device 100. In at
`least one embodiment, a pressure-sensitive adhesive (not
`shown) or the like may be arranged on the outer surface 208
`of the stabilizing matrix 202 in orderto attain better contact/
`adhesion with the skin of the individual and also aid in the
`reduction ofmotionartifacts. Using a pressure sensitive adhe-
`sive may prove advantageoussinceit is typically long lasting,
`keeps adhesive properties in the presence of moisture and
`normal temperature variations, it is nonirritating, non-gum-
`ming, and non-peeling.
`[0033]
`In operation,the light source 104 emits electromag-
`netic radiation into the skin of the individual to optically
`interact with the vasculature and thereby generate an optically
`interacted signal indicative of the amountof electromagnetic
`radiation absorbed bythe hemoglobinin the blood.In atleast
`one embodiment, the light source 104 is configured to emit
`red or infrared light. The device 100 relies on the differential
`absorbanceofthe electromagnetic radiation by different spe-
`cies of hemoglobin. The background absorbance oftissues
`and venous blood absorbs, scatters, and otherwise interferes
`
`with the absorbancedirectly attributable to thearterial blood.
`However, due to the enlargement of the cross-sectional area
`ofthe arterial vessels during the surge ofblood from ventricu-
`lar contraction, a relatively larger signal can be attributed to
`the absorbance of arterial hemoglobin during the systole.
`Whatever is not absorbed is either transmitted through the
`tissue, or reflected back to the detectors 106 for detection.
`[0034] The processing device 110 (FIGS. la and 15) may
`be communicably coupled to the detectors 106 and config-
`ured to receive the signal data generated by the detectors 106.
`In some embodiments, the processing device 110 maypro-
`cess the signal data and provide an output representative of
`cardiac-related information. In other embodiments, however,
`the processing device 110 may be configured to receive and
`wirelessly transmit the signal data to an adjacent computing
`system for processing. By averaging multiple readings
`derived from the detectors 106 and determining the ratio
`peaks of specific wavelengths, the relative absorbance due to
`the arterial blood flow maybe estimated.First, by calculating
`the differences in absorption signals over short periods of
`time during which the systole and diastole are detected, the
`peak net absorbance by oxygenated hemoglobin is estab-
`lished. The software subtracts the major “noise” components
`(from non-arterial sources) from the peak signals to arrive at
`the relative contribution from the arterial pulse.
`[0035] As appropriate, an algorithm may average readings,
`removeoutliers, and/or increase or decrease the light inten-
`sity to obtain a result. In some embodiments, the algorithm
`may be configured to recognize when motion hasinterfered
`with the heartbeat signal, and in such cases the obstructed
`signal
`is then “zeroed;’ thereby denoting that
`the data
`obtained was unanalyzable. Such calculations and determi-
`nations maybefacilitated using, for example, the commer-
`cially-available signal measurement and analysis display
`software program LABVIEW™orthe like. The resulting
`calculations provide a measurementofarterial oxygen satu-
`ration in the vasculature of the individual, and also allows
`calculation of the shape ofthe pulse of the individual, which
`can be developed into a PPG trace. The PPG trace may then,
`in turn, be displayed on a screen associated with the device
`100, as described below, or may be displayed for consider-
`ation by the adjacent machine-readable medium.
`[0036] Referring now to FIGS. 3a and 36, with continued
`reference to FIGS. 1a-b and 2a-c,illustrated is an exemplary
`housing 300 that may be used to houseor otherwiseretain the
`device 100, according to one or more embodiments. Asillus-
`trated in FIG. 3a, the housing 300 may include a body 302
`having a front surface 303 and a back surface 305. The back
`surface 305 may define a recess 304 which extends to a
`bottom surface 306 thereof. The bottom surface 306 may
`define one or more ports 308 (three shown), which may sub-
`stantially correspond to the ports 112 described above with
`reference to FIGS. 1a and 1b. Accordingly,the ports 308 may
`provide wired access to the device 100, such as via the one or
`more ports 112. The ports 308 may extend from the bottom
`surface 306 to a front surface 303 (substantially occluded in
`FIG. 3a) of the housing 300.
`the device 100 may be
`[0037]
`In some embodiments,
`removably coupled to the back surface 305. In other embodi-
`ments, however, the recess 304 may be configured to receive
`or otherwise seat the device 100 therein, as shown in FIG.35.
`Accordingly, the back side 206 (FIG. 2a) of the device 100
`may be configured to engage or otherwise substantially mate
`with the bottom surface 306 ofthe housing 300 whenproperly
`
`8
`
`

`

`US 2013/0267854 Al
`
`Oct. 10, 2013
`
`coupled. The device 100 may be removably coupled to the
`housing 300 using, for example, adhesives, mechanical fas-
`teners, VELCRO®, combinations thereof, or the like. In at
`least one embodiment, however, as shown in FIG. 3c, the
`stabilizing matrix 202 may serve to hold the device 100
`within the housing 300.
`[0038] While the body 302 is shown as being generally
`circular in shape,it will be appreciated that any shape may be
`employed without departing from the scope ofthe disclosure.
`The body 302 mayfurther includeor otherwise define oppos-
`ing elongate apertures 310a and 3105. The elongate apertures
`310a,b may be configured to receive portionsofa strap,belt,
`or band (not shown) usedto attach the housing 300 to the wrist
`of an individual, similar to how a strap or band used on a
`wristwatch would function. The strap or band mayfunction to
`hold the stabilizing matrix 202 (FIGS. 2a-c) into proper con-
`tact with the skin of the individual, and may be adjustable
`based on sizing. In one embodiment, the strap may beinter-
`weaved in the opposing elongate apertures 310a,b but also
`extend across the back side 305 of the housing 302, at least
`partially interposing the device 100 and the back side 305.
`Such an embodiment may help to apply an even pressure to
`the device 100 against the skin of the individual and thereby
`improvethe resulting signal.
`[0039] Referring to FIG.3c,illustrated is an embodimentof
`the device 100 as arranged within the housing 300 and being
`substantially covered by the stabilizing matrix 202. As
`depicted, the stabilizin