(12) United States Patent
`Hicks et al.
`
`111111
`
`1111111111111111111111111111111111111111111111111111111111111
`US006745061Bl
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 6,745,061 Bl
`Jun.l,2004
`
`(54) DISPOSABLE OXIMETRY SENSOR
`
`(75)
`
`Inventors: Christopher Hicks, Boulder, CO (US);
`Norma M. Prince, Lyons, CO (US)
`
`(73) Assignee: Datex-Ohmeda, Inc., Madison, WI
`(US)
`
`( *) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(21) Appl. No.: 10/225,940
`
`(22)
`
`Filed:
`
`Aug. 21, 2002
`
`(51)
`(52)
`(58)
`
`(56)
`
`Int. Cl? .................................................. A61B 5/00
`U.S. Cl. ........................................ 600/344; 600/323
`Field of Search ................................. 600/310, 322,
`600/323, 340, 344
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,825,872 A
`4,830,014 A
`4,865,038 A
`4,964,408 A
`5,041,187 A
`5,237,994 A
`5,246,003 A
`5,249,576 A
`5,263,244 A
`5,425,360 A
`5,427,093 A *
`5,452,717 A
`5,469,845 A
`5,520,177 A
`
`5/1989
`5/1989
`9/1989
`10/1990
`8/1991
`8/1993
`9/1993
`10/1993
`11/1993
`6/1995
`6/1995
`9/1995
`11/1995
`5/1996
`
`Tan eta!.
`Goodman et a!.
`Rich eta!.
`Hink eta!.
`Hink eta!.
`Goldberger
`DeLonzor
`Goldberger et a!.
`Centa eta!.
`Nelson
`.............. 600/323
`Ogawa et a!.
`Branigan et a!.
`DeLonzor et a!.
`Ogawa eta!.
`
`5,671,529 A
`5,678,544 A
`5,782,757 A *
`RE36,000 E
`5,913,819 A
`6,014,576 A
`6,073,038 A
`* cited by examiner
`
`9/1997
`10/1997
`7/1998
`12/1998
`6/1999
`1!2000
`6/2000
`
`Nelson ........................ 29/825
`DeLonzor et a!.
`Diab et a!. .................. 600/323
`Swedlow et a!.
`Taylor et a!.
`............... 600/323
`Raley ......................... 600/344
`Wang et a!.
`................ 600/323
`
`Primary Examiner--Eric F. Winakur
`(74) Attorney, Agent, or Firm-Marsh Fischmann &
`Breyfogle LLP
`
`(57)
`
`ABSTRACT
`
`The invention is directed to a disposable oximetry sensor
`having an integrally formed connector. In one aspect, the
`sensor includes a clear flexible substrate on which a light
`emitter and/or light detector (collectively active component
`(s)) are mounted to allow those components to emit/detect
`light though the clear substrate and a second patient-side
`surface of that substrate. The clear substrate will generally
`contain one or more electrically conductive traces, prefer(cid:173)
`ably formed through a printing process, for interconnection
`to the active components. In this regard, the clear substrate
`acts as the electrical connector and lens structure for the
`active components reducing the overall part count for the
`sensor's assembly. Additional materials/layers may be added
`to the sensor including an adhesive layer, a compressible
`material layer, a light blocking layer, and/or a heat sink for
`thermal management. Generally, any additional layers/
`materials applied the patient-side of the clear substrate will
`be substantially transparent to allow light curing of adhe(cid:173)
`sives utilized to connect components to the sensor though
`the patient-side surface of the sensor during production.
`
`34 Claims, 13 Drawing Sheets
`
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`Apple Inc.
`APL1008
`U.S. Patent No. 8,989,830
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`0001
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`

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`U.S. Patent
`U.S. Patent
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`Jun. 1, 2004
`Jun.1,2004
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`Sheet 1 of 13
`Sheet 1 of 13
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`US 6,745,061 B1
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`U.S. Patent
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`Jun. 1, 2004
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`Sheet 2 of 13
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`US 6,745,061 Bl
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`318 316
`320
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`U.S. Patent
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`Jun.l,2004
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`U.S. Patent
`U.S. Patent
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`Jun. 1, 2004
`Jun.1,2004
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`Sheet 4 of 13
`Sheet 4 of 13
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`US 6,745,061 B1
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`Jun. 1, 2004
`Jun.1,2004
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`Sheet 5 of 13
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`U.S. Patent
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`Jun.l,2004
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`Sheet 6 of 13
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`U.S. Patent
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`Jun.l,2004
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`Sheet 7 of 13
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`US 6,745,061 Bl
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`42
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`102
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`72a
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`110
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`104
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`

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`U.S. Patent
`U.S. Patent
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`Jun.l,2004
`Jun. 1, 2004
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`Sheet 8 of 13
`Sheet 8 of 13
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`US 6,745,061 Bl
`US 6,745,061 B1
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`38
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`U.S. Patent
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`Jun.l,2004
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`Sheet 9 of 13
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`U.S. Patent
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`Jun.1,2004
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`Sheet 10 of 13
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`U.S. Patent
`U.S. Patent
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`Jun. 1, 2004
`Jun.1,2004
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`Sheet 11 of 13
`Sheet 11 of 13
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`U.S. Patent
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`Jun. 1, 2004
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`Sheet 12 of 13
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`U.S. Patent
`U.S. Patent
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`Jun. 1, 2004
`Jun.1,2004
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`Sheet 13 of 13
`Sheet 13 of 13
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`US 6,745,061 B1
`US 6,745,061 Bl
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`40
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`FIG.15
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`

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`US 6,745,061 Bl
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`1
`DISPOSABLE OXIMETRY SENSOR
`
`FIELD OF THE INVENTION
`
`The present invention is generally directed to photopl(cid:173)
`ethysmographic measurement instruments, and more spe(cid:173)
`cifically to disposable pulse oximetry sensors.
`
`BACKGROUND
`
`A common technique used to monitor blood oxygen levels
`is pulse oximetry. In this regard, it is known that the light
`transmissivity and color of blood is a function of the oxygen
`saturation of the heme in the blood's hemoglobin. For
`example, heme that is saturated with oxygen appears bright
`red because saturated heme is relatively permeable to red
`light. In contrast, heme that is deoxygenated appears dark
`and bluish as it is less permeable to red light. A pulse
`oximeter system measures the oxygen content of arterial
`blood by utilizing a pulse oximetry sensor to first illuminate
`the blood with, for example, red and infrared radiation and
`determine the corresponding amounts of red and infrared
`radiation that are absorbed by the heme in the blood. In turn,
`such light absorption amounts may be employed by a pulse
`oximetry monitor in conjunction with known calibration
`information to determine blood oxygen levels.
`Pulse oximetry sensors generally include one or more
`light emitters, a detector(s), and a means for holding these
`components relative to a patient's tissue. These sensors may
`generally be classified as reusable or disposable. Reusable
`sensors typically are more intricate and designed for mul(cid:173)
`tiple uses on multiple patients. In this regard, reusable
`sensors generally must be cleaned between use on different
`patients. Disposable sensors are typically simplified sensors
`that are used for a predetermined period on a single patient
`and discarded. Accordingly, disposable sensors may in some
`instances be more desirable than their reusable counterparts.
`
`SUMMARY OF THE INVENTION
`
`Accordingly, one object of the present invention is to
`provide a disposable pulse oximetry sensor that has a
`reduced part count and it therefore easily produced.
`Another objective of the present invention is to provide a
`pulse oximetry sensor that lends itself to production through
`an automated process.
`A further objective of the present invention is to provide
`a disposable sensor that is economical to manufacture and
`use while providing required sensor performance.
`The inventors of the present invention have recognized
`the increased need for the use of disposable medical sensors 50
`and in particular disposable pulse oximetry sensors. This
`increased need arises due to, inter alia, concerns in properly
`cleaning medical instruments between uses of communi(cid:173)
`cable diseases, such as AIDS and Hepatitis B. In this regard,
`patients as well as hospitals may prefer using new medical 55
`instruments, that is, medical instruments that have not been
`used previously. Additionally, the inventors have recognized
`that although reusable pulse oximetry sensors tend to ini(cid:173)
`tially be more expensive, their ability to be reused may
`lower their per-use cost below that of disposable pulse 60
`oximetry sensors currently existing, leaving hospitals and
`patients torn between their preferences and the financial
`realities of the health care system. Accordingly, the inven(cid:173)
`tors have devised a reduced part count pulse oximetry sensor
`that is easily produced resulting in a disposable pulse 65
`oximetry sensor that is cost effective on a per-use basis in
`comparison with reusable pulse oximetry sensors.
`
`2
`One or more of the above objectives and additional
`advantages are indeed realized by the present invention
`where, in one aspect, a pulse oximetry sensor having an
`integrally formed connector is provided. The sensor includes
`5 a substantially clear flexible substrate that may be con(cid:173)
`formed about a portion of a patient's tissue, such as a finger.
`This flexible clear substrate may be formed from any
`material that provides the desired flexibility and is substan(cid:173)
`tially transparent, allowing for emitting and detecting light
`10 signals through this clear substrate. A particularly apt sub(cid:173)
`strate may be made from a polymer thick film (PTF) such as
`polyester. Mounted on a top surface of the clear flexible
`substrate is at least one active pulse oximetry component.
`That is, at least one light emitter, such as a light emitting
`15 diode, and/or a light detector, such as a photodiode.
`Particularly, these active components are mounted on the top
`surface of the clear substrate such that they emit/detect light
`through the clear substrate and its bottom surface. In this
`regard, the clear substrate acts as a lens covering the active
`20 surfaces of the light emitter and/or light detector and reduc(cid:173)
`ing the overall part count required for the pulse oximetry
`sensor. Further, as noted, the sensor has an integrally formed
`connector that allows the flexible substrate to be intercon(cid:173)
`nected to, for example, an electrical pin connector connected
`25 to a pulse oximetry monitor.
`Various refinements exist of the features noted in relation
`to the subject first aspect of the present invention. Further
`features may also be incorporated into the subject first aspect
`of the present invention as well. These refinements and
`30 additional features may exist individually or in any combi(cid:173)
`nation. For example, the bottom surface of the clear flexible
`substrate (i.e., the patient side of the sensor) may contain an
`adhesive and/or a release liner covering the adhesive for
`selectively securing the sensor to a patient's tissue.
`35 Additionally, a compressible material layer may be disposed
`on the patient side surface of the flexible sensor for increased
`patient comfort. Preferably, any compressible material layer
`utilized will contain apertures aligned with each light emitter
`and/or light detector mounted on the top side of the clear
`40 flexible substrate, allowing light to be emitted and/or
`detected through these apertures free from interference.
`Further, the flexible sensor may contain a light blocking
`layer applied to the top surface of the clear flexible substrate
`to minimize the effect of ambient light sources upon the
`45 sensor. This light blocking layer may include a separate
`substrate interconnected to the clear flexible substrate or
`some sort of opaque coating applied to the top surface of the
`clear flexible substrate.
`Regardless of which additional features the sensor
`utilizes, in a one embodiment, all materials applied to the
`bottom surface (i.e., patient side) of the clear flexible sub(cid:173)
`strate contain a substantially clear portion aligned with the
`active pulse oximetry components. As will be appreciated,
`this provides for increased light transfer between a light
`emitter and/or detector upon application to an appendage as
`well as allowing for the utilization of light (e.g., ultra violet
`(UV) light or high intensity visible light) to cure various
`light-curable adhesives that may be used to mount one or
`more of the components to the clear flexible substrate during
`manufacture. For example, the light emitter and/or detector
`may be encapsulated on top of the clear substrate using a
`light-curable clear adhesive to stabilize the emitter/detector
`as well as provide increased focusing of light into or from
`the clear substrate. Light may be applied through these
`layers and the bottom surface of the clear substrate to cure
`the adhesive(s). In a further embodiment, all the materials
`applied to the bottom surface of the clear substrate will be
`
`0015
`
`

`
`US 6,745,061 Bl
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`3
`at least partially transparent materials to allow light curable
`adhesives to be utilized in laminating the various materials
`together. In addition, or alternatively, thermal and/or
`mechanical pressure may be utilized to initiate or complete
`the cure of adhesives as well as thermally bond (i.e., 5
`laminate) one or more of the various material layers
`together.
`In a second aspect of the present invention, a pulse
`oximetry sensor is provided comprising a substantially clear
`flexible substrate that may be conformed about a patient's 10
`tissue having, mounted on its top surface, at least one active
`pulse oximetry component. Again these active components
`(i.e., light emitter and/or light detector) are mounted on the
`clear substrate's top surface such that they emit/detect light
`through the clear substrate and its bottom surface. Further, 15
`the sensor includes at least one electrically conductive trace
`formed on the clear flexible substrate. The electrically
`conductive trace(s) is formed on the same surface (i.e., top
`surface) on which the emitters/detectors are mounted and
`provides an electrical connection between the integrally 20
`formed connector and the active components. This trace may
`be formed of any appropriate conductive material so long as
`it allows the substrate to freely flex. Examples of appropriate
`materials include thin metallic foils (e.g., 0.001 in) that may
`be stamped onto and/or melted into the clear substrate and 25
`conductive inks that may be printed onto the clear substrate.
`Light emitters and detectors typically include a semicon(cid:173)
`ductor die that contains first and second electrical contact
`pads that must be electrically interconnected with a power
`source to function. In this regard the light emitter and/or
`detector will be electrically interconnected to at least one
`electronically conductive trace. That is the emitter/detector
`may be mounted such that it electrically contacts the con(cid:173)
`ductive trace using, for example, a conductive epoxy to
`attach an electrical contact pad on the emitter/detector to one
`or more electrically conductive traces.
`Various refinements exist of the features in relation to the
`subject second aspect of the present invention. For example,
`the clear flexible substrate may have a plurality of electrical
`conductive traces formed on the surface containing the 40
`emitter and/or detector. In this regard, the active components
`(i.e., emitter and detector) may each be electrically inter(cid:173)
`connected to first and second electrical traces. That is, each
`active component may be electrically interconnected to
`"out" and "return" legs of what forms an electrical circuit 45
`when the sensor is connected to a pulse oximetry monitor.
`Further, the subject second aspect of the present invention
`may utilize any additional components interconnected to the
`flexible substrate such as those discussed above in reference
`to the first aspect of the present invention. Again, any
`additional components interconnected to the bottom surface
`of the subject second aspect of the present invention will
`preferably be at least partially transparent to realize the
`above described benefits.
`In one embodiment of the second aspect of the present
`invention, the conductive traces are formed on the clear
`flexible substrate using a conductive ink, such as a silver
`epoxy, that is deposited onto the clear substrate. In this
`regard, the conductive traces may be deposited on the clear
`flexible substrate using a printing process such as, but not
`limited to, inkjet printing, screen printing, or pad printing.
`As will be appreciated, the use of ink printing allows for
`formation of conductive traces on the clear flexible substrate
`in a simplified manner in comparison to the utilization of, for
`example, chemical etching of a conductive surface such as
`copper, the use of a stamped lead frame, and/or the use of
`discrete wire conductors.
`
`4
`In a related aspect of the present invention, a pulse
`oximetry sensor is provided having a clear flexible substrate
`with at least one electrically conductive trace formed
`thereon and at least one light emitter electrically intercon(cid:173)
`nected to one or more of those traces. The sensor further
`includes a thermal element adapted to transfer thermal
`energy away from the light emitter. As will be appreciated,
`when the light emitter is active (i.e., emitting light) the light
`emitter and the clear substrate to which it is mounted may
`become uncomfortably warm. This is especially evident
`where conductive ink traces are utilized on the clear flexible
`substrate, as conductive ink traces may not have enough
`thermal mass to effectively transfer heat away from the light
`emitter. Accordingly, undue heat build up around the light
`emitter may result in patient discomfort and/or tissue dam(cid:173)
`age. Though in the present invention the thermal element is
`utilized to counteract the reduced thermal mass resulting
`from use of printed conductive traces, it will be appreciated
`that a thermal element may also be utilized with any pulse
`oximetry sensor to reduce potentially damaging heat con(cid:173)
`centrations. The thermal element may be formed of any
`material having high thermal conductivity such as, but not
`limited to, a copper sheet or washer that is thermally
`connected to the light emitter. In any case, the thermal
`element acts as a heat sink operable to draw heat away from
`the light emitter and dissipate that heat over an increased
`area to prevent excessive heat build up in a single area
`adjacent to a patient's tissue.
`A related aspect of the present invention provides a sensor
`30 utilizing a clear flexible substrate on which a light emitter
`and/or detector is mounted for emitting/detecting light
`through the clear flexible substrate. This sensor further
`incorporates an insulative layer in a face-to-face relationship
`with at least a portion of a patient side surface (i.e., the
`35 bottom surface of the clear substrate) for creating a tem(cid:173)
`perature differential between a patient's tissue and the
`bottom surface of the clear flexible substrate. As noted
`above, sensor active components and, in particular, the light
`emitting components may become uncomfortably warm
`during normal usage. In this regard, the insulative layer may
`be disposed on the bottom surface of the clear flexible
`substrate to provide a thermal buffer or "stand-off" between
`a patient's tissue and the bottom surface of the clear sub(cid:173)
`strate.
`In one embodiment, this insulative layer will contain
`apertures aligned with each of the active components
`mounted on the top surface of the clear flexible substrate.
`This arrangement allows the active components to emit/
`detect light free from interference. In a further embodiment
`50 utilizing the insulative layer, a substantially clear intercon(cid:173)
`necting layer will be interconnected to patient side surface of
`the insulative layer allowing the apertures within the insu(cid:173)
`lative layer to be sandwiched between the clear intercon(cid:173)
`necting layer and the patient surface of the clear substrate.
`55 As will be appreciated, this produces an air pocket of "dead"
`air space between the patient's tissue and the bottom surface
`of the clear substrate, further reducing the possibility of
`undue heat build up against a patient's tissue. This pocket is
`preferably sealed to prevent the pocket deflation when the
`60 sensor is applied to the patient's tissue. Adhesives and/or
`thermal bonding of the various layers may be utilized to
`producing a sealed pocket.
`In a further related aspect of the present invention, the
`flexible pulse oximetry sensor utilizes a first substrate hav-
`65 ing a top surface with one or more electrically conductive
`traces formed thereon and a second flexible substrate having
`a bottom surface with one or more electrical conductive
`
`0016
`
`

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`US 6,745,061 Bl
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`6
`FIG. 3 shows a cross sectional view of a photodetector
`attached to the lead frame of FIG. 2 taken along section lines
`A-A';
`FIG. 4 shows a plan view of the metallic lead frame of
`5 FIG. 2 utilizing an adhesive encapsulant to stabilize the
`active components;
`FIG. 5 shows a top plan view of a disposable sensor in
`accordance with the present invention;
`FIG. 6 shows a cross sectional view of the layers making
`up the disposable sensor of FIG. 5 taken along section lines
`A-A';
`FIG. 7 shows a plan view of one embodiment of the
`electrically conductive traces formed on the top surface of
`15 the sensor of FIG. 5;
`FIG. Sa shows a cross sectional view of one of the active
`components interconnected to the top surface of the dispos(cid:173)
`able sensor of FIG. 5 taken along section lines B-B';
`FIG. Sb shows a cross sectional view of an alternate
`connection one of the active components interconnected to
`the top surface of the disposable sensor of FIG. 5 taken along
`section lines B-B';
`FIG. 9 shows a perspective view of one embodiment the
`integral connector of the disposable sensor of FIG. 5;
`FIG. 10 shows a stiffener utilized with the integral con(cid:173)
`nector of FIG. 9;
`FIG. 11 shows a cross sectional view of an alternate
`combination of layers making up the disposable sensor of
`FIG. 5 taken along section lines A-A', wherein said sensor
`includes a thermal element;
`FIG. 12 shows a plan view of a flexible sensor in
`accordance with the present invention that utilizes two
`flexible substrates having electrically conductive traces
`formed thereon;
`FIG. 13 shows a plan view of a flexible sensor of the
`present invention having an integrally formed cord;
`FIGS. 14a-d shows a process for straightening the cord of
`the flexible sensor of FIG. 13;
`FIG. 15 shows a fresnel lens that may be incorporated into
`the clear substrate of any of the above embodiments of the
`sensor.
`
`DETAILED DESCRIPTION
`
`5
`traces formed thereon. In this embodiment, one or more
`active sensor components (i.e. light emitters/detectors) are
`physically and electronically mounted to one of the sub(cid:173)
`strates as well as being electrically interconnected to a
`conductive trace on the second flexible substrate. In this
`regard, the first and second flexible substrates may be
`disposed in a face-to-face relationship where the top and
`bottom surfaces containing the electrically conductive traces
`are disposed towards one another. As will be appreciated,
`this provides a sensor where the electrical traces, such as 10
`printed conductive ink traces, as well as the active sensor
`components are sandwiched between the first and second
`substrates and are thereby protected from the environment.
`One or more of the above noted objectives and advantages
`may also be realized by an inventive method for forming a
`pulse oximetry sensor. The inventive method includes the
`steps of mounting onto the top surface of a substantially
`clear substrate, a light emitter for emitting light through the
`bottom surface of the substrate and/or a light detector for
`detecting light through the bottom surface of the substrate. 20
`The step of mounting may further include the step of
`electrically connecting the emitter/detector to one or more
`electrical traces associated with the clear substrate using, for
`example, a conductive epoxy. The mounting step may also
`include encapsulating the emitter/detector with a clear adhe- 25
`sive for increasing the light focusing capabilities of that
`component. The method further includes the step of apply(cid:173)
`ing light through the bottom surface of the clear substrate to
`at least partially cure one or more light-curable adhesives
`used for mounting emitters/detectors to the clear substrate. 30
`A method is also provided for producing a flexible sensor
`having an integrally formed cord as well as an integrally
`formed connector. The process includes the steps of depos(cid:173)
`iting at least one electrically conductive trace between first
`and second points on the surface of a flexible substrate sheet, 35
`which may be a clear flexible substrate. In order to produce
`an integrally formed cord having a length greater than that
`of the longest edge of the flexible substrate sheet, these
`traces are formed in a concentric pattern, continuously
`winding about a first point and gradually approaching a 40
`second point. For example, a first point may be located near
`the middle of a substantially square substrate sheet while the
`second point is located at one of the corners of the substrate
`sheet. The electrical traces connect the first and second
`points by winding about the first point in, for example, a 45
`circular or rectangular spiral pattern until they reach the
`second point. In one embodiment, the electrically conduc(cid:173)
`tive traces are formed between the first and second points on
`the substrate sheet using a conductive ink printing processes.
`Additionally, at least one light emitter and/or light detector 50
`are mounted on the flexible substrate and are electrically
`interconnected the conductive traces. Preferably, these
`emitters/detectors are mounted at the end of a trace to
`maximize the resulting length of the cord. Finally, the
`flexible substrate is cut between concentric windings of the 55
`electrical trace between the first and second points to form
`a flexible concentric strip having at least one electrically
`conductive trace between its first and second ends. This
`flexible concentric strip is then straightened to provide a
`flexible sensor having an integrally formed cord.
`
`FIGS. 1-4 illustrate one embodiment of a prior art flexible
`oximetry sensor. FIG. 1 shows an exploded view of the
`sensor assembly 350. Included within the assembly 350 are
`upper and lower flexible members 304 and 300, respectively.
`These members 300, 304 are thermally bonded to one
`another sandwiching a leadframe 308 between their inside
`surfaces. This leadframe 308 contains active components
`(i.e., LEDs and a photodetector) for use in oximetry
`measurements, as will be more fully discussed in reference
`to FIG. 2. As will be appreciated, at least one of the flexible
`members 300 and 304 contains apertures 360, 362 aligned
`with the active components to allow a line of sight to exist
`between these active components and to a patient's tissue
`upon sensor application. The sensor assembly 350 also
`contains a pin connector 346 interconnected to a cable 364
`that is soldered to the leadframe 308. The pin connector 346
`is used to connect sensor assembly 350 to an oximetry
`monitor (not shown).
`FIG. 2 shows a close-up view of the leadframe 308. The
`65 leadframe 308 is preferably composed of the conducting
`material, such as copper, and is preformed (e.g., stamp
`pressed or chemically etched) into a shape and size for use
`
`60
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 shows an exploded perspective view of a prior art
`pulse oximetry sensor;
`FIG. 2 shows a plan view of the metallic lead frame
`utilized with the pulse oximetry sensor of FIG. 1;
`
`0017
`
`

`
`US 6,745,061 Bl
`
`7
`with the upper and lower flexible members 304 and 300. The
`lead frame contains a plurality of conductive traces 310--320
`for conducting electrical signals through the sensor's active
`components 330--334. In particular the active components
`include LEDs 330, 332 and photodetector 334. These com(cid:173)
`ponents 330-334 are each electrically interconnected to two
`of the traces to forms an electrical circuit there through. FIG.
`3 shows a side view of the interconnection of the photode(cid:173)
`tector 334 to the leadframe 308 along section lines A-A'. It
`will be appreciated that the LED's 330 and 332 are inter(cid:173)
`connected in a substantially identical manner albeit to dif(cid:173)
`ferent electrical traces. As shown, the photodetector 334
`contains first and second contact pads 336 and 338 located
`on its top and bottom surfaces, respectively. The bottom
`contact pad 338 as well as the photodetector 334 is inter(cid:173)
`connected to trace 320 by a conductive adhesive bond 322.
`In this regard, a drop of the conductive adhesive may be
`placed on the surface of the trace 320 after which the
`photodetector 334 is pressed into the conductive adhesive
`thereby creating an electrical interconnection between the
`bottom contact pad 338 and the trace 320. The conductive
`adhesive is then cured using, for example, heat. All the
`active components 330--334 are mounted directly to a trace
`312, 318, and 320 which has a width greater than the
`respective component 330-330 mounted thereon.
`Accordingly, the emitting and detecting surfaces of the
`components 330-334 are necessarily mounted such that they
`emit/detect in a direction other than the direction of the trace
`on which they are mounted. As shown in FIG. 3, the
`photodetector's active surface is located on its top surface.
`Likewise, the active surfaces of the LEDs 330 and 332 are
`mounted to emit from their top surfaces, however, it will be
`appreciated that the LEDs 330, 332 also emit a substantial
`portion of light through their side surfaces. To complete the
`electrical circuit through the photodetector 334 the top
`contact pad 336 is interconnected to a second electrical trace
`310. This connection is made using a ductile connector wire
`324 (e.g., gold) that is wire bonded to the top contact pad
`336, routed to the second electrical trace 310, and wire
`bonded to the second trace 310.
`The ductile wire connector 324 is made of a small gauge
`wire. Additionally, the individual traces 310-320 must
`remain electrically isolated from one another to prevent
`electrical shorting there between. Therefore, in order to
`stabilize the wire connector 324 and isolate the traces
`310--320 a clear nonconductive adhesive is utilized to encap(cid:173)
`sulate the active components 330-334 and portions of the
`traces 310-320. That is, a first adhesive drop 332 encapsu(cid:173)
`lates the LEDs 330, 332 and a portion of all the traces
`310--320 while a second adhesive drop 332 encapsulates the
`photodetector 334 and traces 320 and 310. These adhesive
`drops 332 are cured using UV light, light and/or heat to form
`clear solids which provide structural stability for the sensor
`350 as well as lenses to help direct light emitted or received
`by the active components 330--334.
`As will be appreciated, the prior art sensor 350 requires
`the forming of a conductive lead frame 308, application of
`active components 330-334 using a conductive adhesive,
`curing of the conductive adhesive, wire bonding, application
`and curing of clear adhesive bubbles to stabilize the sensor
`assembly 350, soldering the lead frame 308 to a pin con(cid:173)
`nector 346 and finally sandwiching the lead frame assembly
`between the upper and lower flexible members 300 and 304.
`FIG. 5 shows a top view of one embodiment of a low cost
`oximeter sensor assembly 30 having an integral connector
`34, in accordance with the present invention. Generally, the
`sensor 30 is formed having a flexible sheet-like laminate 50
`
`5
`
`8
`structure which includes first and second opposing wings 52,
`54, as well as a finger-tip projection 56 oriented between and
`projecting perpendicular to the wings 52, 54. The wings 52,
`54, along with the finger-tip projection 56, are used for
`flexibly wrapping the sensor 30 about a finger 60 (shown in
`phantom) such that one or more LED's 40, 42 are disposed
`on a first surface of the finger and a photodetector 38 i