Surgery – Diagnostic testing – Measuring or detecting nonradioactive constituent of body...
Reexamination Certificate
2001-12-20
2004-07-06
Winakur, Eric F. (Department: 3736)
Surgery
Diagnostic testing
Measuring or detecting nonradioactive constituent of body...
Reexamination Certificate
active
06760607
ABSTRACT:
BACKGROUND OF THE INVENTION
Description of the Related Art
Pulse oximetry is a widely accepted noninvasive procedure for measuring the oxygen saturation level of arterial blood, an indicator of a person's oxygen supply. Early detection of low blood oxygen level is critical in the medical field, for example in critical care and surgical applications, because an insufficient supply of oxygen can result in brain damage and death in a matter of minutes. A pulse oximetry system includes a sensor applied to a patient, a pulse oximeter, and a patient cable connecting the sensor and the pulse oximeter. The pulse oximeter may be a standalone device or may be incorporated as a module or built-in portion of a multiparameter patient monitoring system and typically provides a numerical readout of the patient's oxygen saturation, a numerical readout of pulse rate, and an audible indicator or “beep” that occurs in response to each pulse. In addition, the pulse oximeter may display the patient's plethysmograph, which provides a visual display of the patient's pulse contour and pulse rate.
SUMMARY OF THE INVENTION
FIGS. 1 and 2
illustrate one type of circuit configuration for a pulse oximetry sensor, such as described in U.S. Pat. No. 5,782,757 entitled “Low Noise Optical Probe,” which is assigned to the assignee of the present application, and is incorporated herein by reference. As shown in
FIG. 1
, a sensor
100
that can be attached, for example, to an adult patient's finger or an infant patient's foot, has both red and infrared LEDs
110
and a photodiode detector
120
. For finger attachment, the sensor is configured so that the LEDs
110
project light through the fingernail and into the blood vessels and capillaries underneath. The photodiode
120
is positioned at the finger tip opposite the fingernail so as to detect the LED emitted light as it emerges from the finger tissues. The sensor
100
may have an identification (ID) element, such as a resistor
130
with multiple uses depending on the manufacturer, such as an indicator of LED wavelength, sensor type or manufacturer. LED pinouts
140
connect the LEDs
110
to LED drivers in a pulse oximetry monitor (not shown) via a patient cable (not shown). Detector pinouts
150
connect the detector
120
to front end signal conditioning and analog-to-digital conversion within the monitor, also via the patient cable.
As shown in
FIG. 2
, a sensor circuit may comprise a flexible circuit substrate
200
having printed traces
204
of deposited or etched conductive material, including connector traces
206
. Mounted on the substrate
200
and soldered to the traces
204
so as to create an electrical connection are an LED component
210
having both red and infrared LEDs
110
(
FIG. 1
) encapsulated on a leaded carrier, a detector component
220
having a photodiode
120
(
FIG. 1
) encapsulated on a leaded carrier and an ID element
230
such as a resistor
130
(
FIG. 1
) on a leadless carrier. The connector traces
206
have detector pinouts
140
, LED pinouts
150
and shielding pinouts
260
for noise suppression.
A ribbon cable substrate pulse oximetry sensor utilizes a ribbon cable to physically mount and electrically connect the sensor components. A ribbon cable substrate has several advantages over a flexible circuit or similar substrate for manufacturing a pulse oximetry sensor. Ribbon cable can be purchased “off-the-shelf” in bulk quantities, such as on large spools, as compared with flexible circuits, which are custom manufactured. Further, unlike flexible circuits that must be manufactured in various sizes for various sensor types, ribbon cable can be cut-to-length as required. In additional, as described below, ribbon cable is amenable to automated manufacturing techniques. Thus, use of ribbon cable as a sensor substrate can significantly reduce sensor costs as well as simplify the manufacturing process.
One aspect of a physiological sensor comprises a ribbon cable having a plurality of conductors extending within an insulation layer between a first end and a second end. A detector is mounted to the ribbon cable and electrically connected to at least a first pair of the conductors. An emitter is also mounted to the ribbon cable and electrically connected to at least a second pair of the conductors. At least one of the detector and the emitter are mounted at the first end of the ribbon cable, and a connector is mounted to the ribbon cable at the second end. A retainer is mounted to the ribbon cable and configured to removably attach the ribbon cable to tissue so that the emitter may transmit light into a tissue sample and the detector may receive light from the tissue sample.
In one embodiment, the detector is mounted to the ribbon cable at the first end and the emitter is mounted to the ribbon cable between the first and second ends. In this manner, the ribbon cable can be folded around a tissue portion of a patient so that the emitter opposes the detector on either side of the tissue portion. In another embodiment, the connector comprises a plurality of pins each enclosing one of a plurality of end portions of the conductors, where the insulation is stripped from the end portions at the second end. An encapsulant is disposed around a portion of the pins and the second end so as to form a housing portion of the connector. Alternatively, a welded connector shell is disposed around a portion of the pins and the second end so as to form a housing portion of the connector.
In a further embodiment, the ribbon cable comprises a first conductive layer shielding the first pair of conductors, where the first conductive layer has a first embedded conductor extending to the connector. A detector shield may be disposed around the detector and electrically connected to the first embedded conductor. Also, there may be a second conductive layer shielding the first pair and the second pair of conductors, where the second conductive layer has a second embedded conductor extending to the connector.
Another aspect of a physiological sensor is a manufacturing method comprising the step of cutting a substrate from a length of ribbon cable having a plurality of conductors to form a connector end and a component end of the substrate. The length of the substrate is measured to conform to a particular sensor type. Further steps are stripping a first portion of insulation from the component end to expose a detector contact portion of the conductors and stripping a second portion of insulation from the component end to expose an emitter contact portion of the conductors. Additional steps are attaching a detector and an emitter at the component end so that a plurality of detector leads of the detector are electrically connected to the detector contact portion and a plurality of emitter leads of the emitter are electrically connected to the emitter contact portion. Additional steps are forming a connector at the connector end configured to electrically communicate with a patient cable and mounting the substrate to a retainer configured so that the substrate can be attached to living tissue. In one embodiment the attaching step comprises the substep of crimping the detector leads and the emitter leads onto the detector contact portion and the emitter contact portion, respectively.
In one embodiment, the forming step comprises the substeps of stripping a third portion of insulation from the connector end to expose a connector contact portion of the conductors, disposing a plurality of pins around the connector contact portion, and encapsulating the pins to form a connector housing. In an alternative embodiment, a substep is welding a connector shell around the pins to form a connector housing. The connector contact portion is in electrical communication with the detector contact portion and the emitter contact portion. Another embodiment comprises the further steps of removing an insulation window between the connector end and the component end to expose an ID element contact portion of the conductors, and attaching an ID e
Knobbe Martens Olson & Bear LLP
Masimo Corporation
McCrosky David J.
Winakur Eric F.
LandOfFree
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