Abstract:
A pulse oximeter sensor has both a reusable and a disposable portion. The reusable portion of the sensor preserves the relatively long-lived and costly emitter, detector and connector components. The disposable portion of the sensor is the relatively inexpensive adhesive tape component that is used to secure the sensor to a measurement site, typically a patient&#39;s finger or toe. The disposable portion of the sensor is removably attached to the reusable portion in a manner that allows the disposable portion to be readily replaced when the adhesive is expended or the tape becomes soiled or excessively worn. The disposable portion may also contain an information element useful for sensor identification or for security purposes to insure patient safety.

Description:
PRIORITY CLAIM TO RELATED APPLICATIONS 
       [0001]    The present application claims priority benefit under 35 U.S.C. §120 to, and is a continuation of U.S. patent application Ser. No. 11/415,600, filed on May 2, 2006, entitled “Resposable Pulse Oximetry Sensor,” now U.S. Pat. No. 8,000,761, which is a continuation of U.S. patent application Ser. No. 10/741,777, filed on Dec. 19, 2003, entitled “Resposable Pulse Oximetry Sensor,” now U.S. Pat. No. 7,039,449, which is a continuation of U.S. patent application Ser. No. 10/128,721, filed on Apr. 23, 2002, entitled “Resposable Pulse Oximetry Sensor,” now U.S. Pat. No. 6,725,075, which is a continuation U.S. patent application Ser. No. 09/456,666, filed Dec. 12, 1999, entitled “Resposable Pulse Oximetry Sensor,” now U.S. Patent No.  6 , 377 , 829 . The present application incorporates the foregoing disclosures herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates in general to sensors for measuring oxygen content in the blood, and, in particular, relates to resposable (reusable/disposable) sensors having an information element contained therein. 
       BACKGROUND 
       [0003]    Early detection of low blood oxygen is critical in a wide variety of medical applications. For example, when a patient receives an insufficient supply of oxygen in critical care and surgical applications, brain damage and death can result in just a matter of minutes. Because of this danger, the medical industry developed oximetry, a study and measurement of the oxygen status of blood. One particular type of oximetry, pulse oximetry, is a widely accepted noninvasive procedure for measuring the oxygen saturation level of arterial blood, an indicator of the oxygen status of the blood. A pulse oximeter relies on a sensor attached to a patient in order to measure the blood oxygen saturation. 
         [0004]    Conventionally, a pulse oximeter sensor has a red emitter, an infrared emitter, and a photodiode detector. The sensor is typically attached to a patient&#39;s finger, earlobe, or foot. For a finger, the sensor is configured so that the emitters project light through the outer tissue of the finger and into the blood vessels and capillaries contained inside. The photodiode is positioned at the opposite side of the finger to detect the emitted light as it emerges from the outer tissues of the finger. The photodiode generates a signal based on the emitted light and relays that signal to an oximeter. The oximeter determines blood oxygen saturation by computing the differential absorption by the arterial blood of the two wavelengths (red and infrared) emitted by the sensor. 
         [0005]    Conventional sensors are either disposable or reusable. A disposable sensor is typically attached to the patient with an adhesive wrap, providing a secure contact between the patient&#39;s skin and the sensor components. A reusable sensor is typically a clip that is easily attached and removed, or reusable circuitry that employs a disposable attachment mechanism, such as an adhesive tape or bandage. 
         [0006]    The disposable sensor has the advantage of superior performance due to conformance of the sensor to the skin and the rejection of ambient light. However, repeated removal and reattachment of the adhesive tape results in deterioration of the adhesive properties and tearing of the tape. Further, the tape eventually becomes soiled and is a potential source of cross-patient contamination. The disposable sensor must then be thrown away, wasting the long-lived emitters, photodiode and related circuitry. 
         [0007]    On the other hand, the clip-type reusable sensor has the advantage of superior cost savings in that the reusable pulse sensor does not waste the long-lived and expensive sensor circuitry. However, as mentioned above, the clip-type reusable sensor does not conform as easily to differing patient skin shape, resulting in diminished sensitivity and increased ambient light. 
         [0008]    Similar to the clip-type reusable sensor, the circuit-type reusable sensor advantageously does not waste the sensor circuitry. On the other hand, the circuit-type reusable sensor fails to provide quality control over the attachment mechanism. Much like the disposable sensors, the attachment mechanism for the circuit-type reusable sensor may become soiled or damaged, thereby leading to cross-patient contamination or improper attachment. Moreover, because the reusable circuit is severable from the attachment mechanism, operators are free to use attachment mechanisms that are either unsafe or improper with regard to a particular type of reusable circuitry. 
         [0009]    Based on the foregoing, significant and costly drawbacks exist in conventional disposable and reusable oximetry sensors. Thus, a need exists for an oximetry sensor that incorporates the advantages found in the disposable and reusable sensors, without the respective disadvantages. 
       SUMMARY OF THE INVENTION 
       [0010]    Accordingly, one aspect of the present invention is to provide a reusable/disposable (resposable) sensor having a disposable adhesive tape component that can be removed from other reusable sensor components. This hybrid sensor combines the longevity and associated cost advantages of the reusable sensor with the performance features of the disposable. 
         [0011]    In one embodiment of the resposable sensor, the disposable tape includes an information element along with a mechanism for the electrical connection of the information element to the emitters. The information element provides an indication to an attached oximeter of various aspects of the sensor. 
         [0012]    According to another embodiment, the information element provides an indication of the sensor type. According to yet another embodiment, the information element provides an indication of the operating characteristics of the sensor. In yet another embodiment, the information element provides security and quality control. For instance, the information element advantageously indicates that the sensor is from an authorized supplier. 
         [0013]    According to yet another embodiment, the information element is advantageously located in the disposable portion and configured to be in communication with the reusable portion via a breakable conductor. The breakable conductor is also located within the disposable portion such that excessive wear of the disposable portion results in isolation of the information element, thereby indicating that the disposable portion should be replaced. Moreover, the information element may comprise one or more passive or active components, ranging from a single coding resistor to an active circuit, such as a transistor network, a memory device, or a central processing component. 
         [0014]    Therefore, one aspect of the present invention is a pulse oximetry sensor including a reusable portion having an emitter configured to transmit light through tissue, a detector configured to receive light from tissue, a first contact, an external connector configured to attach to a monitor, and electrical circuitry configured to provide electrical communications to and from the external connector, the emitter, the detector and the first contact. The pulse oximetry sensor also includes a disposable portion configured to attach the reusable portion to the tissue. The disposable portion has an information element, a breakable conductor, and a second contact electrically connecting the information element and the breakable conductor, the second contact configured to create an electrical connection to the first contact when the disposable portion is combined with the reusable portion. 
         [0015]    Another aspect of the present invention is a resposable sensor for noninvasively measuring a physiological parameter in tissue. The resposable sensor includes a reusable portion and a disposable portion. The disposable portion has at least one of an information element and a conductor electrically connected to the reusable portion. Moreover, the disposable portion is configured to secure the reusable portion to a measurement site. 
         [0016]    Another aspect of the present invention is a method of providing disposable oximeter sensor elements. The method includes forming a disposable housing configured to receive a reusable electronic circuit. The method also includes forming at least one of an information element and a conductor associated with the disposable housing and configured to be disconnected from the reusable electronic circuit when the disposable housing is damaged, overused, or repeatedly attached. 
         [0017]    Another aspect of the present invention is a method of providing reusable oximeter sensor elements. This includes forming a reusable electronic circuit configured to electrically connect with electronic components of a disposable housing and to employ the disposable housing for attachment to a measurement site. 
         [0018]    Another aspect of the present invention is a method of measuring a tissue characteristic. This method includes creating a sensor through combining reusable electronic circuitry with a first disposable material such that an electrical connection is made between the reusable electronic circuitry and electronic components associated with the first disposable material. Moreover, the method includes attaching the sensor to a measurement site, removing the sensor, separating the reusable electronic circuitry from the first disposable material, and recombining the reusable electronic circuitry with a second disposable material. 
         [0019]    Another aspect of the present invention is a pulse oximeter having a sensor including a reusable portion and a disposable portion. The disposable portion includes an information element electrically connected to the reusable portion through a breakable conductor. The breakable conductor is configured to electrically disconnect the information element from the reusable portion in the event of overuse, damage, or excessive reattachment of the disposable portion. Moreover, the pulse oximeter includes a monitor, and a cable for connecting the sensor to the monitor. 
         [0020]    Yet another aspect of the present invention is a pulse oximeter sensor element having a disposable material that incorporates electronic components. The disposable material is configured to removably receive reusable oximeter sensor elements such that the electronic components electrically connect with the reusable oximeter sensor elements. Moreover, the disposable material is configured to secure the reusable oximeter sensor elements to a measurement site. 
         [0021]    Another aspect of the present invention is a pulse oximeter sensor element including reusable electronic circuitry configured to electrically connect with electronic components of a disposable material and to employ the disposable material for attachment to a measurement site. 
         [0022]    Another aspect of the present invention is a resposable sensor for measuring a tissue aspect. The resposable sensor includes a face tape, a base tape removably attached to the face tape, and reusable measurement circuitry removably secured between the face tape and the base tape. The reusable measurement circuitry is also configured to connect to an external monitor and configured to measure an aspect of tissue at a measurement site. Moreover, the face tape includes at least one of an information element and a breakable conductor connected to the reusable measurement circuitry when the reusable measurement circuitry is secured to the face tape. 
         [0023]    Another aspect of the present invention is a resposable sensor having a reusable emitter and detector removably connected to a patient cable. The resposable sensor also includes a replaceable envelope having electronic circuitry configured to attach to the reusable emitter and detector such that the electronic circuitry monitors at least one characteristic of the resposable sensor. Moreover, the replaceable envelope is configured to removably receive the reusable emitter and detector and configured to secure the reusable emitter and detector to a measurement site. 
         [0024]    Yet another aspect of the present invention is a pulse oximetry sensor having an emitter, a detector and a connector. The emitter is configured to transmit light through tissue and the detector is configured to receive light from tissue to measure a physiological parameter. Further, the connector is configured to provide electrical communications between the detector and emitter and a monitor. The pulse oximetry sensor includes a reusable portion having the emitter, the detector, the connector and a first contact in communication with the connector. Moreover, the sensor includes a disposable portion having a second contact, an information element and a conductive element disposed on an adhesive substrate configured to secure the reusable portion to a measurement site. The disposable portion removably attaches to the reusable portion in a first position such that the first contact contacts the second contact. The disposable portion detaches from the reusable portion in a second position. Also, the conductive element has a continuity condition connecting the information element to the second contact so that the information element is in communication with the connector. The conductive element has a discontinuity condition isolating the information element from the second contact and the connector. The discontinuity condition results from use of the disposable portion substantially beyond a predetermined amount. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  illustrates a circuit diagram of a conventional disposable sensor having an information element. 
           [0026]      FIGS. 2A and 2B  illustrate perspective views of the conventional disposable sensor. 
           [0027]      FIG. 3  illustrates an exploded view of a resposable sensor having two disposable tape layers, according to one embodiment of the invention. 
           [0028]      FIG. 4  illustrates a top view of one of the disposable tape layers of  FIG. 3  incorporating an information element. 
           [0029]      FIG. 5  illustrates a top view of one of the disposable tape layers of  FIG. 3  incorporating a breakable conductor. 
           [0030]      FIGS. 6A and 6B  illustrate cross-sectional views of a portion of the disposable tape layer of  FIG. 5 . 
           [0031]      FIG. 7  illustrates a top view of one of the disposable tape layers of  FIG. 3  incorporating the information element with a breakable conductor. 
           [0032]      FIG. 8A and 8B  illustrate a top view and a side view, respectively, of one of the disposable layers of  FIG. 3  configured as a fold-over tape. 
           [0033]      FIG. 9A  illustrates a perspective view of a resposable sensor having a disposable portion configured as a tape sleeve and a reusable portion directly attached to a patient cable, according to another embodiment of the invention. 
           [0034]      FIG. 9B  illustrates a perspective view of a resposable sensor having a reusable portion removably attached to a patient cable, according to another embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0035]    The configuration of an information element for an oximeter sensor and method of reading an information element with an attached oximeter is described in U.S. Pat. No. 5,758,644, assigned to the assignee of the current application, and incorporated by reference herein. Accordingly, the configuration and the implementation of an information element will be greatly summarized as follows. 
         [0036]      FIG. 1  illustrates a conventional oximeter sensor circuit  100 . The oximeter sensor circuit  100  includes an emitter  105  comprising a first LED  107  and a second LED  110 . The oximeter sensor circuit further includes an information element comprising a resistor  115 . The first LED  107 , the second LED  110  and the resistor  115  are connected in parallel. The parallel connection has a common input electrical connection  120  and a common return  125 . The oximeter sensor circuit  100  also includes a photodetector  130  having an input electrical connection  135  connected to one end and having the common return  125  connected to the other end. 
         [0037]    As mentioned, the resistor  115  is provided as an information element that can be read by an attached oximeter. In order to read the resistor  115 , the oximeter drives the oximeter sensor circuit  100  at a level where the emitter  105  draws effectively insignificant current. As is well understood in the art, the emitter  105  becomes active only if driven at a voltage above a threshold level. Thus, at this low level, significantly all of the current through the input electrical connection  120  flows through the resistor  115 . By reducing the drive voltage across the input electrical connection  120  and common return  125  to a low enough level to not activate the emitter  105 , the emitter  105  is effectively removed from the oximeter sensor circuit  100 . Thus, the oximeter can determine the value of the resistor  115 . 
         [0038]    The value of the resistor  115  can be preselected to indicate, for example, the type of sensor (e.g., adult, pediatric, or neonatal), the operating wavelength, or other parameters about the sensor. The resistor  115  may also be utilized for security and quality control purposes. For example, the resistor  115  may be used to ensure that the oximeter sensor circuit  100  is configured properly for a given oximeter. For instance, the resistor  115  may be utilized to indicate that the oximeter sensor circuit  100  is from an authorized supplier. 
         [0039]    An information element other than the resistor  115  may also be utilized. The information element need not be a passive device. Coding information may also be provided through an active circuit, such as a transistor network, memory chip, or other identification device. 
         [0040]    Furthermore, it will be understood by a skilled artisan that a number of different circuit configurations can be implemented that allow the oximeter sensor circuit  100  to include an information element. For example, the emitter  105  and the information element may each have individual electrical connections. 
         [0041]    As mentioned above, the resistor  115  is preselected such that at low drive voltages, it is the only circuit element sensed by the oximeter. On the other hand, the resistor  115  can also be preselected be of a sufficiently high value that when the drive voltage rises to a level sufficient to drive the emitter  105 , the resistor  115  is effectively removed from the oximeter sensor circuit  100 . Thus, the resistor  115  does not affect normal operations of the emitter  105 . In summary, an information element may form an integral part of the oximeter sensor circuit  100  by providing valuable information to the attached oximeter. 
         [0042]      FIGS. 2A and 2B  illustrate a conventional disposable sensor  200 . The disposable sensor  200  includes an adhesive substrate  205  having an elongated center portion  210  with front and rear flaps,  215  and  220 , extending outward from the elongated center portion  210 . The adhesive substrate  205  may also have an image  225  superimposed on the adhesive substrate  205  so as to indicate proper use. 
         [0043]    The elongated center portion  210  includes the oximeter sensor circuit  100  of  FIG. 1 . For example, the emitter  105  is housed on an underside of the elongated center portion  210  approximately beneath the superimposed image  225 . Thus, as shown in  FIG. 2A , the emitter  105  may be housed approximately beneath the asterisk superimposed on the image of a fingernail. On the other hand, the photodetector  130  is housed on the topside of the elongated center portion  210  in proximity with the rear flaps  220 . 
         [0044]    The elongated center portion  210  further includes an electrical connector  230  to drive the emitter  105  and to receive an output from the photodetector  130 . The electrical connector  230  is preferably configured to attach to a connector cable  235  via a sensor connector  240 . Also, the connector cable  235  attaches to or connects with an oximeter via an oximeter connector  245 . 
         [0045]      FIG. 2B  illustrates an example of how the disposable sensor  200  wraps the front and rear flaps  215  and  220  around a finger such that the adhesive substrate  205  provides a secure contact between the patient&#39;s skin, the emitter  105  and the photodetector  130 .  FIG. 2B  also illustrates an example of the sensor connector  240  (shown in broken lines) encompassing the electrical connector  230 . 
         [0046]    As shown in  FIGS. 1-2B , the conventional disposable sensor  200  integrates the components of the conventional oximeter sensor circuit  100  such that disposal of the disposable sensor  200  includes disposal of the longer lasting, expensive circuitry found therein. 
         [0047]      FIG. 3  illustrates an exploded view of one embodiment of a resposable (reusable/disposable) sensor  300  according to the present invention. In this embodiment, the resposable sensor  300  includes a reusable portion  305  having an emitter  306 , a photodetector  307  and an electrical connector  308 . The resposable sensor also includes a disposable portion  310  having a face tape layer  315  and a clear base tape layer  320 . As shown in  FIG. 3 , the disposable portion  310  attaches to the reusable portion  305  by sandwiching the reusable portion  305  between a face tape layer  315  and a clear base tape layer  320 . 
         [0048]    According to this embodiment, conventional adhesives or other attaching methodology may be used to removably attach the face tape layer  315  to the clear base tape layer  320 . Furthermore, the adhesive properties associated with the base of the conventional disposable sensor  200  may be the same as the adhesive properties on the base of the clear base tape layer  320 , as both portions are provided to attach to the patient&#39;s skin. 
         [0049]    As mentioned, the disposable portion  310  removably attaches to the reusable portion  305  in, for example, a sandwich or layered style. After removably attaching the disposable portion  310  to the reusable portion  305 , the resposable sensor  300  functions similar to the disposable sensor  200 , i.e., the resposable sensor  300  wraps flaps around a patient&#39;s tissue such that the emitter  306  and the photodetector  307  align on opposite sides of the tissue. However, in contrast to the disposable sensor  200 , the resposable sensor  300  provides for reuse of the reusable portion  305 . For example, when the disposable portion  310  becomes contaminated, worn, or defective, rather than discarding the entire resposable sensor  300 , the disposable portion  310  is removed such that the reusable portion  305  may be re-removably attached to a new disposable portion  310 . The discarding of the disposable portion  310  completely avoids cross-contamination through the reuse of adhesive tapes between patients without wasting the more costly and longer lasting sensor circuitry of the resposable portion  305 . Note that optional sterilization procedures may be advantageously performed on the reusable portion  305  before reattachment to either the new disposable portion  310  or to the patient, in order to further ensure patient safety. 
         [0050]      FIG. 4  illustrates a top view of an embodiment of the face tape layer  315  of the disposable portion  310  of the resposable sensor  300 . According to this embodiment, the face tape layer  315  further includes an information element  405  as an integral part of the face tape layer  315 . In this embodiment, the information element  405  is a resistive element made by depositing a conductive ink trace having a predetermined length and width. As is known in the art, the length, width and conductivity of the conductive ink trace determines the resistance of the resistive element. The information element  405  is deposited between contacts  410  that are also implemented with conductive ink. It will be understood by a skilled artisan that a variety of methods can be used for mating the contacts  410  with the electrical circuitry of the reusable portion  305 . For example, the contacts  410  may advantageously physically touch the leads or the electrical connector  308  such that the reusable portion  305  is electrically configured to include the information element  405 . Such a configuration employs the oximeter sensor circuit  100  of  FIG. 1 , having elements thereof distributed in both the reusable portion  305  and the disposable portion  310  of the resposable sensor  300 . 
         [0051]    In the foregoing embodiment, the disposable portion  310  comprises the information element  405  along with the face tape layer  315  and the clear base layer  320 . As mentioned, the disposable portion  310  is removably attached to the reusable portion  305  and is employed in a similar manner as the disposable sensor  200 . In contrast to the disposable sensor  200 , when the disposable portion  310  of the resposable sensor  300  becomes worn, the disposable portion  310  and the information element  405  are discarded and the reusable portion  305  is saved. By discarding the information element, the attached oximeter can perform quality control. For example, if the reusable portion  305  is reattached to a patient using either a simple adhesive or any other non-authorized disposable mechanism, the resposable sensor  300  will not include the information element  405 . As mentioned above, an attached oximeter can recognize the absence of the information element  405  and create an appropriate response indicating inappropriate use of the reusable portion  305  of the resposable sensor  300 . 
         [0052]      FIG. 5  illustrates a top view of yet another embodiment of the face tape layer  315  of the disposable portion  310  of the resposable sensor  300 . In this embodiment, the face tape layer  315  includes a breakable conductor  505  comprising a conductive ink trace located approximately along the periphery of the face tape layer  315 . This location ensures that a tear along the periphery of the face tape layer  315  results in a tear, or electrical discontinuity, in the breakable conductor  505 . For example,  FIGS. 6A and 6B  illustrate the face tape layer  315  in which the breakable conductor  505  is layered between a tape stock  605  and a tape base  610 . The reusable portion  305  of the resposable sensor  300  then attaches to the tape base  610  through a pressure sensitive adhesive (PSA)  615 . The PSA  615 , the conductor  505  and the tape base  610  include a score  620  such that multiple attachment and removal of the resposable sensor  300  will result in a peripheral tear, or electrical discontinuity, in the breakable conductor  505 , as illustrated in  FIG. 6B . 
         [0053]    Thus, like the information element  405 , the breakable conductor  505  also provides security and quality control functions. In particular, repeated use of the disposable portion  305  of the resposable sensor  300  advantageously severs at least one part of the breakable conductor  505 . An attached oximeter can detect such severance and initiate an appropriate notification to, for example, monitoring medical personnel. Providing security and quality control through a breakable conductor advantageously assists in controlling problems with patient contamination or improper attachment due to weakened adhesives. 
         [0054]      FIG. 7  illustrates yet another embodiment of the face tape layer  315 . In this embodiment, the face tape layer  315  combines the breakable conductor  505  and the information element  405 . In this embodiment, the breakable conductor  505  is printed in a serpentine pattern to further increase the probability of a discontinuity upon the tearing of any portion of the face tape layer  315 . This combination of the information element  405  and the breakable conductor  505  advantageously adds significant safety features. For example, in this embodiment, the information element  405  is connected serially with the breakable conductor  505  and in parallel with the emitter  306  of the reusable portion  305 . Therefore, any discontinuity or tear in the breakable conductor  505  separates the information element  405  from the circuitry of the reusable portion  305 . 
         [0055]    According to the foregoing embodiment, the attached oximeter receives an indication of both overuse and misuse of the resposable sensor  300 . For example, overuse is detected through the tearing and breaking of the breakable conductor  505 , thereby removing the information element  405  from the resposable sensor  300  circuitry. In addition, misuse through employment of disposable portions  310  from unauthorized vendors is detected through the absence of the information element  405 . Moreover, misuse from purposeful shorting of the contacts  410  is detected by effectively removing the emitter  306  from the circuit, thereby rendering the resposable sensor  300  inoperative. Therefore, the resposable sensor  300  of this embodiment advantageously provides a multitude of problem indicators to the attached oximeter. By doing so, the resposable sensor  300  advantageously prevents the likelihood of contamination, adhesive failure, and misuse. The resposable sensor  300  also advantageously maintains the likelihood of quality control. 
         [0056]    A skilled artisan will recognize that the concepts of  FIGS. 3-7  may be combined in total or in part in a wide variety of devices. For example, either or both of the breakable conductor  505  and the information element  405  may advantageously be traced into the clear base tape layer  320  rather than into the face tape layer  315 . 
         [0057]      FIGS. 8A and 8B  illustrate yet another embodiment of the disposable portion  310  of the resposable sensor  300  according to the present invention. As shown in this embodiment, the disposable portion  310  includes a face tape layer  805  and a clear base tape layer  810 . According to this embodiment, the clear base tape layer  810  includes a preattached section  815  and a fold over section  820 . The preattached section  815  attaches approximately one third of the face tape layer  805  to the clear base tape layer  810 . On the other hand, the fold over section  820  forms a flap configured to create a cavity between the face tape layer  805  and the clear base tape layer  810 . The cavity is configured to receive the reusable portion  305  of the resposable sensor  300 . According to one embodiment, a release liner  825  fills the cavity and separates the face tape layer  805  from the clear base tape layer  810 . When the release liner  825  is removed, newly exposed adhesive on the fold over section  820  and the face tape layer  805  removably attaches the reusable portion  305  between the face tape layer  805  and fold over section  820  of the clear base tape layer  810 . 
         [0058]    According to another embodiment, the cavity is so formed that adhesive is not needed. For example, the fold over section  820  may comprise resilient material that can form a friction fit relationship so as to fix the reusable portion  305  in an appropriate position relative to the disposable portion  310 . On the other hand, the fold over section  820  may also comprise material having other than resilient or adhesive properties, but still allow for proper placement of the reusable portion  305  and disposable portion  310  on the patient. For example, hook-and-loop type materials like VELCRO® may be used. 
         [0059]    It will be understood that a skilled artisan would recognize that the fold over embodiment of the responsible sensor  300  may employ the properties discussed in relation to  FIGS. 3-7 , such as the information element  405  and the breakable wire  505 . 
         [0060]      FIG. 9A  illustrates an embodiment of a resposable sensor  900  integrated with an attached patient cable  905 , according to another embodiment of the invention. In this embodiment, a disposable portion  910  is attached to a reusable portion  915  by removably inserting the reusable portion  915  into a tape envelope  920  formed in the disposable portion  910 . 
         [0061]    A skilled artisan will recognize that the disposable portion  910  may include the information element  405 , the breakable wire  505 , or both. Inclusion of one or both of these electronic components in the resposable sensor  900  advantageously provides the security, quality control, and safety features described in the foregoing embodiments. 
         [0062]      FIG. 9B  illustrates an embodiment of a resposable sensor  300  of  FIG. 3 , according to another embodiment of the invention. According to this embodiment, the resposable sensor  300  removably attaches to the patient cable  905  via a sensor connector  925 . The patient cable  905  then attaches to an oximeter via an oximeter connector  930 . Use of the sensor connector  925  enables the replacement of both the reusable portion  305  of the resposable sensor  300  without replacement of the sensor connector  925  or patient cable  905 . In such an embodiment, the disposable portion  310  would follow a different, more frequent, replacement schedule than that of the reusable portion  305 . 
         [0063]    A skilled artisan will recognize that the variety of configurations described above that include the information element  405 , the breakable wire  505 , or both, may be incorporated into the embodiment of  FIG. 9B . 
         [0064]    Although the foregoing invention has been described in terms of certain preferred embodiments, other embodiments will be apparent to those of ordinary skill in the art. For example, select aspects of  FIGS. 3-9B  may be combined. For example, the envelope configured disposable portion  910  of  FIG. 9A  may be combined with the reusable portion  305  of  FIG. 3 . 
         [0065]    Additionally, other combinations, omissions, substitutions and modifications will be apparent to the skilled artisan in view of the disclosure herein. Accordingly, the present invention is not intended to be limited by the reaction of the preferred embodiments, but is to be defined by reference to the appended claims.