Abstract:
Embodiments described herein may include systems and methods for monitoring physiological parameters of a patient. Specifically, embodiments disclose the use of a generally self-contained pulse oximeter that is small and lightweight, such that it may be comfortably affixed to a patient to provide physiological data pertaining to the patient. Embodiments also provide methods of using and manufacturing a pulse oximetry patch.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 12/935,747, filed Sep. 30, 2010, which is a national state entry of W.O. Publication No. 2009/124076, filed Mar. 31, 2009, and claims priority to Provisional Application No. 61/072,600, filed Mar. 31, 2008, the disclosures of which are hereby incorporated by reference in their entirety for all purposes. 
     
    
     BACKGROUND 
       [0002]    The present disclosure relates generally to medical devices and, more particularly, to medical monitoring devices. 
         [0003]    This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
         [0004]    In the field of medicine, doctors often desire to monitor certain physiological characteristics of their patients. Accordingly, a wide variety of devices have been developed for monitoring physiological characteristics. Such devices provide doctors and other healthcare personnel with the information they need to provide the best possible healthcare for their patients. As a result, such monitoring devices have become an indispensable part of modern medicine. 
         [0005]    One technique for monitoring certain physiological characteristics of a patient is commonly referred to as pulse oximetry, and the devices built based upon pulse oximetry techniques are commonly referred to as pulse oximeters. Pulse oximetry may be used to measure various blood flow characteristics, such as the blood-oxygen saturation of hemoglobin in arterial blood, the volume of individual blood pulsations supplying the tissue, and/or the rate of blood pulsations corresponding to each heartbeat of a patient. 
         [0006]    Pulse oximeters typically utilize a non-invasive sensor that is placed on or against a patient&#39;s tissue that is well perfused with blood, such as a patient&#39;s finger, toe, forehead or earlobe. The pulse oximeter sensor emits light and photoelectrically senses the absorption and/or scattering of the light after passage through the perfused tissue. The data collected by the sensor may then be used to calculate one or more of the above physiological characteristics based upon the absorption or scattering of the light. More specifically, the emitted light is typically selected to be of one or more wavelengths that are absorbed or scattered in an amount related to the presence of oxygenated versus de-oxygenated hemoglobin in the blood. The amount of light absorbed and/or scattered may then be used to estimate the amount of the oxygen in the tissue using various algorithms. 
         [0007]    Pulse oximeters and other medical devices are typically mounted on stands that are positioned around a patient&#39;s bed or around an operating room table. When a caregiver desires to command the medical device (e.g., program, configure, and so-forth), the caregiver may manipulate controls or push buttons on the monitoring device itself. The monitoring device typically provides results or responses to commands on a Liquid Crystal Display (“LCD”) screen mounted in an externally visible position on the medical device. Patient data, alerts, and other information may be displayed on the monitor directly, or may be transmitted to a central computer monitored by caregivers. 
         [0008]    This conventional configuration, however, may have several disadvantages, particularly in emergency situations which may occur remotely from a hospital or medical environment. For example, conventional monitors are too heavy and bulky to be worn or constantly moved around to follow a patient. Additionally, in emergency situations, a convenient power supply may not be readily available, and the time required to set up the monitoring system may not be available considering other pressing emergency needs of the patient. The lack of time or a convenient power source may be particularly problematic in large scale emergencies wherein several patients require prompt medical treatment from limited medical personnel working with limited resources. Additionally, the bulk and expense of conventional monitors may make it logistically and economically unfeasible to have large numbers of such monitors on-hand and ready to be transported to emergency sites. It may be desirable, therefore, to have a pulse oximeter that is small, lightweight, inexpensive and battery operated, such that it can be worn by a patient and possibly disposed of after a single use. 
       SUMMARY 
       [0009]    Certain aspects commensurate in scope with the original claims are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain embodiments and that these aspects are not intended to limit the scope of the claims. Indeed, the claims and disclosure may encompass a variety of aspects that may not be set forth below. 
         [0010]    Some embodiments described herein are directed to a wholly contained pulse oximetry system that may be worn by a patient. Certain embodiments may include an upper layer that includes a display, a bottom layer that includes one or more light emitters and one or more light detectors for acquiring physiological data from a patient and a middle layer between the upper layer and lower layer that holds the circuitry of the pulse oximetry system, including sensor circuitry, parameter processing circuitry, and display circuitry. 
         [0011]    Other embodiments described herein are directed to methods of generating physiological data by a pulse oximetry system that is worn by a patient in the form of a patch for example. The pulse oximetry system may perform the acts of: driving LEDs to emit a light signal into a tissue to be tested; receiving a modified light signal after it has been transmitted through or reflected from the tissue to be tested; generating a physiological parameter based on the modified light signal; and generating a display output of the physiological parameter on an outer surface of the patch. 
         [0012]    Other embodiments described herein are directed to methods of monitoring a patient by affixing a wholly contained pulse oximeter to the tissue of a patient and observing a physiological data display included on the pulse oximeter. 
         [0013]    Still other embodiments described herein are directed to a method of manufacturing a pulse oximeter, such as by providing pulse oximeter circuitry configured to sense, process, and display physiological data of a patient, and enclosing the pulse oximeter circuitry within an enclosure configured to be disposed adjacent to a tissue of the patient. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    Advantages of the disclosure may become apparent upon reading the following detailed description and upon reference to the drawings in which: 
           [0015]      FIG. 1A  is a perspective view of a pulse oximetry patch in accordance with an embodiment in which the display includes a pair of light emitting diodes (LEDs); 
           [0016]      FIG. 1B  is a perspective view of a pulse oximetry patch in accordance with an embodiment in which the display includes a numerical display; 
           [0017]      FIG. 2  is a perspective view of the back side of the pulse oximetry patch of  FIG. 1A  or  1 B in accordance with an embodiment; 
           [0018]      FIG. 3  is a depiction of a pulse oximetry patch of  FIG. 1A  or  1 B disposed adjacent to the forehead of a patient in accordance with an embodiment; 
           [0019]      FIG. 4  is a block diagram of a pulse oximeter of  FIG. 1A  or  1 B in accordance with an embodiment; 
           [0020]      FIG. 5  is a perspective exploded view of the pulse oximeter of  FIG. 1A  in accordance with an embodiment; 
           [0021]      FIG. 6  is a perspective view of the back side of the pulse oximeter circuit board of  FIG. 5  in accordance with an embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    One or more embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
         [0023]    Certain embodiments relate to a wholly contained pulse oximetry system that is small and lightweight such that it can be worn by a patient. Such a pulse oximetry system may be a small, battery operated, flexible patch that may be adhesively or otherwise affixed to a patient. Such a patch may be used once and thrown away. Therefore, such a pulse oximetry patch may be constructed inexpensively, having very simplified features and displays compared to a traditional pulse oximetry system. 
         [0024]      FIG. 1A  is a perspective view of a front side of pulse oximetry patch  10  in accordance with an embodiment. The front side of the pulse oximetry patch  10  is the side that would be visible to a caregiver after the pulse oximetry patch  10  is affixed to a patient. The pulse oximetry patch  10  may be small enough to be affixed to a patient and also holds circuitry utilized for sensing, processing and displaying physiological data of a patient. Because the pulse oximetry patch  10  is to be affixed to a patient, it will typically be small and lightweight. For example, it may have a surface area in the range of approximately three or four square inches, and a thickness in the range of one-eighth of an inch. Additionally, to provide for a secure and comfortable fit, the patch  10  may be flexible. Furthermore, the patch  10  may also include various textual printing on the outer surface, such as, for example, labels, use instructions and model information. As will be explained in more detail below, the patch  10  may be made of any material known in the art such as, for example, polymeric materials. 
         [0025]    The pulse oximetry patch  10  may also include a display, illustrated here as two displays  14  and  16 , which display certain physiological data of a patient. The displays  14  and  16  may display any data that is useful to a caregiver monitoring a patient. As example, the display  14  may include an LED that blinks correlatively with the heart beat of the patient. For another example, the display  16  may be activated or deactivated in response to the blood-oxygen saturation level of a patient. Specifically, in some embodiments the display  16  may light up when the patient&#39;s blood-oxygen level is above acceptable levels, informing the caregiver that the patient&#39;s blood-oxygen level is normal. In alternate embodiments, the display  16  may light up when the patient&#39;s blood-oxygen level is below acceptable levels, alerting the caregiver that the patient&#39;s blood-oxygen level is too low. Furthermore, the displays  14  and  16  may be color coded. For example, the display  16  may include an LED that emits green light when blood-oxygen levels are normal and emits red light when blood-oxygen levels are too low. 
         [0026]    Referring to  FIG. 1B , an embodiment that includes a numerical display  18  is shown. The numerical display  18  may be configured to display any useful numerical data corresponding to a physiological parameter of a patient, such as, for example, a pulse rate and/or a blood-oxygen saturation level. Additionally, the numerical display  18  may be configured to display data corresponding to the pulse oximetry patch  10  itself, such as, for example, battery life and/or whether the patch  10  is transmitting a wireless signal. Furthermore, the display  18  may be configured to cycle through a set of numerical data, either on a timed basis or responsive to an input of the user. 
         [0027]    Referring to  FIG. 2 , one example of the back side of the pulse oximetry patch  10  is shown. The back side  12  of the pulse oximetry patch  10  is the side that is affixed adjacent to the tissue of a patient. As will be explained further below, the pulse oximetry patch  10  detects physiological data of a patient through sensor circuitry that may include an emitter  19  and a detector  20 . The emitter  19  may include one or more LEDs, such as a red LED and an infra-red LED. The detector  20  may be, for example, any kind of photosensor known in the art, such as, for example a photodiode. When operable, both the emitter  19  and detector  20  are in contact with the skin or tissue of a patient. 
         [0028]    To hold the pulse oximetry patch  10  against the patient, the back side  12  of the patch  10  may include an adhesive  22  that is configured to hold the pulse oximetry patch  10  against the skin of a patient. Additionally, to protect the adhesive  22  while the pulse oximetry patch  10  is not in use, a protective sheet  24  may be disposed over the adhesive  22 . The protective sheet  24  may be configured to be removed just prior to the pulse oximetry patch  10  being affixed to the skin of a patient. 
         [0029]    The pulse oximetry patch  10  may be disposed adjacent to any part of a patient&#39;s body that is conducive to measuring physiological parameters and that can support the pulse oximetry patch  10 , such as for example, the forehead or the wrist. It should also be noted that the pulse oximetry patch  10  may be calibrated for use over a particular bodily area or tissue measurement site. 
         [0030]    Referring to  FIG. 3 , an embodiment of a pulse oximetry patch  10  may be held by a headband  28  adjacent to the forehead of a patient  26  above the left eye, for example. A typical headband  28  may be affixed to the pulse oximetry patch  10  along the edges  29  of the pulse oximetry patch  10 . The headband  28  may be made of an elastic material configured to stretch to fit a wide range of head sizes. Additionally, the headband  28  may include a buckle  30  designed to adjust the fit of the headband  28 . In alternate embodiments, the pulse oximetry patch  10  may be held in place with an external adhesive bandage (not shown). In fact, many techniques will be recognized by one of ordinary skill in the art for holding the pulse oximetry patch  10  against the skin of a patient, and the examples recited above should not be considered an exhaustive list of possible embodiments. 
         [0031]    Turning now to  FIG. 4 , a block diagram of a pulse oximetry patch  10  is illustrated in accordance with an embodiment. It will be understood that an actual implementation may include more or fewer components as needed for a specific application. In this embodiment, the pulse oximetry patch  10  may include a red emitter  19 A and an infra-red emitter  19 B that are configured to transmit electromagnetic radiation through the tissue of a patient  26 . In accordance with this embodiment, the emitters  19 A and  19 B may include an LED that emits electromagnetic radiation in the respective region of the electromagnetic spectrum. The emitted radiation transmitted from the emitters  19 A and  19 B into a patient&#39;s tissue is detected by the detector  20  after the radiation has passed through or reflected from blood perfused tissue of a patient  26 . The detector  20  generates a photoelectrical signal correlative to the amount of radiation detected. 
         [0032]    The signal generated by the detector  20  may then be amplified by an amplifier  34 , filtered by a filter  36 , and provided to one or more processor(s)  38 . The processor(s)  38  may include an analog-to-digital converter  52  that converts the analog signal provided by the detector  20  into a digital signal. The analog-to-digital converter  52  may provide the digital signal to the core  54  to be processed for computing physiological parameters related to the patient  26 . For example, the core  54  may compute a percent oxygen saturation of hemoglobin and/or a pulse rate, among other useful physiological parameters, as will be appreciated by one of ordinary skill in the art. By utilizing an analog-to-digital converter  52  within the processor(s)  38 , the size and cost of the patch may be reduced, compared to traditional pulse oximeters that use a separate analog-to-digital converter. In presently contemplated embodiments, the processor(s)  38  may include a Mixed-Signal Microcontroller such as model number C8051F353 available from Silicon Laboratories. 
         [0033]    In addition to computing physiological parameters, the processor(s)  38  may control the timing and intensity of the emitted electromagnetic radiation of the emitters  19 A and  19 B via a light drive circuit  40 . In embodiments, the light drive circuit  40  may be driven by a digital-to-analog converter  48 , included in the processor(s)  38 . By utilizing a digital to analog converter  48  within the microprocessor  38 , the size and cost of the patch may be reduced, compared to traditional pulse oximeters that use a separate digital-to-analog converter. In accordance with an embodiment, the light drive circuit  40  may have a low part count such as the light drive circuit discussed in detail in U.S. Provisional Patent Application No. 61/009,076, entitled “LED Drive Circuit and Method for Using Same.” (TYHC:0008) which was filed Dec. 26, 2007, and is incorporated herein by reference in its entirety for all purposes. The reduced part count of the drive circuit  40  may further reduce the size, complexity, and cost of the pulse oximetry patch  10 . 
         [0034]    Furthermore, the processor(s)  38  may also include a RAM  56  and/or a flash memory  58  coupled to the core processor  54 . The RAM  56  may be used to store intermediate values that are generated in the process of calculating patient parameters. The flash memory  58  may store certain software routines used in the operation of the patch  10 , such as measurement algorithms, LED drive algorithms, and patient parameter calculation algorithms, for example. In certain embodiments, the patch  10  may include simplified pulse oximetry algorithms such that the computer code associated with those algorithms may be contained in the memory components of the processor(s)  38 . 
         [0035]    In some embodiments, the pulse oximetry patch  10  may also include other memory components that are not included in the processor(s)  38 . For example, the patch  10  may include a read-only memory (ROM), which may be used to store such things as operating software for the patch  10  and algorithms for computing physiological parameters. In other embodiments, however, all of the processing memory and measurement software is included in the processor(s)  38 . 
         [0036]    Furthermore, in some embodiments, the patch  10  may also include a long-term memory device used for long-term storage of measured data, such as measured physiological data or calculated patient parameters. In other embodiments, however, the cost and/or part count of the pulse oximetry patch  10  may be further reduced by eliminating any long-term storage of measured data. By eliminating long-term storage of measured data, smaller, less expensive memory components may be utilized, or, alternatively, some memory components may be eliminated. This may reduce the part count and the size and complexity of the pulse oximetry patch  10 , compared to traditional pulse oximetry systems. 
         [0037]    Also included in the pulse oximetry patch  10  is a display that may be coupled to the processor(s)  38  to allow for display of the computed physiological parameters. For example, the display may include an LED display  14 ,  16  operably coupled to the processor(s)  38  and programmed to operate as described above in relation to  FIG. 1 . For another example, the display may include a numerical display  18 , such as a liquid crystal display, and drive circuitry configured to convert the processor  38  output into a format suitable for driving the numerical display  18 . 
         [0038]    Embodiments may also include a wireless device  50  configured to transmit computed patient parameters such as, for example, pulse rate, blood-oxygen saturation, or the raw data. The wireless device  50  may include any wireless technology known in the art. In an embodiment, the sensor  14  may transmit data via a wireless communication protocol such as WiFi, Bluetooth or ZigBee. 
         [0039]    Turning now to  FIG. 5 , an exploded view of a pulse oximetry patch  10  is shown. In some embodiments, the pulse oximetry patch  10  may include three layers: a middle layer  60 , a top layer  62 , and a bottom layer  64 . The middle layer  60  may include all or substantially all of the circuitry of the pulse oximeter patch  10 . To operably couple the various circuitries, the middle layer  60  may include a circuit board  72 , which may be a flexible, or “flex,” circuit board, and it may also be double sided. By making the circuit board  72  flexible, the pulse oximetry patch  10  can more easily conform to the contours of a patient while also preventing connection failures within the circuit board  72 . 
         [0040]    The circuit board  72  may include the microprocessor  38 , as well as other circuit components  76 , such as the circuit components discussed above with regard to  FIGS. 4 and 5 . The circuit board  72  may also include one or more batteries  74 . The batteries  74  may be any small, lightweight battery such as a “coin cell” or “button cell.” In some embodiments, the batteries  74  may be lithium ion batteries. In yet other embodiments, the batteries  74  may be nanowire batteries, i.e., high performance lithium ion batteries made from silicon nanowires. The batteries  74  serve to power the circuitry of the pulse oximetry patch  10  and are coupled to the circuitry through contacts  75 . 
         [0041]    In an embodiment, an electrically insulative film (not shown) may optionally be inserted between the batteries  74  and the contacts  75  during manufacture to prevent the pulse oximetry patch  10  from becoming activated prior to its intended use. In some embodiments, the electrically insulative film may be an extension of the protective sheet  24 . For example, the protective sheet  24  may include an extension that is inserted during manufacture into the patch  10  through a small opening in the side of the patch  10 . This extension may be disposed between a battery and its corresponding electrical contact to block the flow of current from the battery. In this way, removal of the protective sheet  24  would simultaneously expose the adhesive  22  and turn on the patch  10 . In some embodiments, the removal of the electrically insulative film may be the only way of actuating the circuitry of the pulse oximetry patch  10 . 
         [0042]    In alternate embodiments, other means of activating the pulse oximetry patch  10  may be included. For example, the pulse oximetry patch  10  may include a power button or switch, or, alternatively, the pulse oximetry patch  10  may include a pressure sensitive button that may be enclosed in the patch  10  and operable through compression of the patch  10 . 
         [0043]    The circuit board  72  may also include the display LEDs  14  and  16 . As stated above, the display LEDs  14  and  16  provide the caregiver with the patient&#39;s physiological data. As such, the display LEDs  14  and  16  align with the display windows  66 , in the top layer  62 . As discussed in relation to  FIG. 1B , the middle layer may also include a numerical display  18 , rather than a set of display LEDs. 
         [0044]    In embodiments, the middle layer  60  may also include a wireless device  50  on the circuit board  72 . As discussed above, the wireless device  50  may allow the pulse oximetry patch  10  to transmit data wirelessly to a remote monitor. As such, the wireless device  50  may include a wireless transmitter circuitry and a radio frequency antenna, such as, for example a microstrip or patch antenna. 
         [0045]    Additionally, although not depicted, embodiments may include one or more pushbuttons coupled to the circuit board  72  of the middle layer  60 . The pushbuttons may allow a user to turn the pulse oximetry patch  10  on or off or change a mode of the pulse oximetry patch  10 . For example, a pushbutton may allow a caregiver to cycle through various physiological data displayed on the numerical display  18 . 
         [0046]    Furthermore, embodiments may also include an alarm and supporting circuitry. The alarm may be used as another way of communicating physiological data of a patient to a caregiver. For example, the alarm may be configured to emit a beeping sound corresponding with the heartbeat of a patient, or the alarm could be configured to sound when the patient&#39;s blood-oxygen saturation level falls below a certain acceptable level. 
         [0047]    Turning briefly to  FIG. 6 , the back side of the circuit board  72  is shown. The back side of the circuit board  72  may include, at least, the emitter  19  and the detector  20 . In embodiments, the emitter  19  includes a red LED and an infra-red LED. The emitter  19  and detector  20  are placed to align with the sensor window  68  in the bottom layer  64 . In some embodiments, the bottom side of the circuit board  72  may include additional circuit components. 
         [0048]    Returning to  FIG. 5 , the pulse oximetry patch  10  may include a top layer  62  and bottom layer  64  that enclose the middle layer  60  to protect the circuitry inside, thus forming a shell around the circuitry and the circuit board  72 . The top layer  62  is the layer that is visible when disposed adjacent to the skin of a patient. As such, the top layer  62  may include display windows  66  that allow display components  14 ,  16 ,  18  to be seen through the top layer  62 . The display windows  66  may be constructed in any manner that allows visible light to pass through the top layer  62 . For example, the display windows  66  may include holes formed in the top layer  62 . Furthermore, the display windows may include a translucent material configured to prevent fluids from entering the pulse oximetry patch  10  through the display windows  66 . Alternatively, in some embodiments, the display windows  66  may include a reduced thickness of the top layer material, such that light may pass through the top layer  62  more easily at the display window  66 . 
         [0049]    The top layer  62  or the bottom layer  64  may also include a battery “door” for allowing access to the batteries  74 . For example, part of the top layer  62  or the bottom layer  64  may swing or slide open to expose a battery compartment, allowing batteries to be changed. Alternatively, an embodiment may be configured such that the batteries are not accessible. As such, the pulse oximetry patch  10  would be intended to be thrown away after the batteries can no longer sufficiently charge the pulse oximetry device  10 , which may be suitable for a disposable, one-use patch. 
         [0050]    The top layer  62  and bottom layer  64  may be formed using any suitable material. In an embodiment, the top layer  62  and the bottom layer  64  may include a metal such as aluminum. In another embodiment, the top layer  62  and bottom layer  64  may include one or more polymers, such as, for example, silicon polymers, polyvinylchloride and polyolefins such as polyethylene. The polymers may be elastomeric to provide for flexibility of the pulse oximetry patch  10  such that it may conform to the tissue of a patient. Additionally, any number of ways for coupling the top layer  62  and the bottom layer  64  may be employed. For example, the layers may be glued, melted or snapped together at the edges. 
         [0051]    In various embodiments, the middle layer  60  may be encased in a unitary outer shell through the use of injection overmolding. As will be appreciated by one of ordinary skill in the art, a typical injection overmolding technique will include placing one or more fully assembled middle layers  60  into a die and injecting a molten thermoplastic into the die to surround the middle layer  60 . The mold may be constructed so that the display windows  66  and the sensor windows  68  are not obstructed. For example, the display LEDs  14  and  16 , the emitter  19  and the detector  20  may be situated at an outer edge of the mold volume such that the molten thermoplastic will not completely cover these components. 
         [0052]    In yet other embodiments, a clamshell style container may be formed in a sheet thermoforming method that will be understood by one of ordinary skill in the art. The clamshell container may then be folded over the middle layer  60  and sealed within the clamshell such as by melting, snapping or gluing the edges together. 
         [0053]    In certain embodiments, the patch  10  may be configured so that the middle layer  60  can be easily removed for later recycling or reuse. In this embodiment, the top layer  62  and bottom layer  64  may be pulled apart without causing damage to the middle layer  60 . The outer layers may then be discarded, while the middle layer  60  may be refitted with new batteries and repackaged with new top and bottom layers  62  and  64 . This may allow a program of recycling to be implemented, in which customers return used pulse oximetry patches to the manufacturer, rather than discarding them. In this way, a manufacturer of the disclosed embodiment may be better able to conform to electronic waste regulations, such as those called for in the Waste Electrical and Electronic Equipment Directive recently legislated by the European Union. 
         [0054]    Some embodiments of a pulse oximetry patch  10  may also include a disabling mechanism that prevents unauthorized manipulation or reuse of the patch  10 . In this regard, the processor(s)  38  may be programmed to recognize whether the outer layers of the patch  10  have been separated. For example, a conductive contact may be included in the patch  10  that electrically couples an input/output (I/O) port of the processor(s)  38  to a zero-voltage reference. The I/O port may also be electrically coupled to a non-zero voltage through a high-resistance pull-up resistor. Furthermore, the conductive contact may be physically coupled to the top layer  62  and/or the bottom layer  64 , such that separation of the layers will cause the conductive contact to open electrically, allowing the I/O port to float to the higher voltage level through the pull-up resistor. The processor(s)  38  may be configured such that detection of a non-zero voltage at the I/O port at start-up or during operation disables the patch  10 . 
         [0055]    Another example of a disabling mechanism may include an small integrated circuit (IC) chip such as an Erasable Programmable Read-Only Memory (EPROM) or a 1-Wire® chip available from Dallas Semiconductor Corp. The IC chip may be communicatively coupled to the processor(s)  38  and may hold information such as manufacturer information that may be read by the processor(s)  38 . The processor(s)  38  may be programmed to read and verify the IC information as part of a start-up routine, for example. Furthermore, a contact may be electrically coupled to the IC and physically coupled to the upper layer  62  and/or lower layer  64  such that separation of the layers will cause the information stored on the IC to be erased, thereby disabling the patch  10 . In this way, the information stored on the IC would have to be reprogrammed before the middle layer  60  could be reused.