Abstract:
A disposable electrically conductive band for a re-usable RFID tag having an RFID tag holder, an electrical continuity contact within a loop on an end of the band, an electrically conductive landing area on a tongue of the band, the tongue being insertable through the loop to secure the band around a body to be monitored by an RFID system, the tongue thereby engaging a portion of the landing area with the electrical continuity contact. The conductive landing area has a series of electrical continuity dimples in each of which there is an electrical contact to an electrical pathway around the electrically conductive band. The RFID tag transmits an alarm to the monitoring agency whenever the band has been tampered with, severed, or otherwise circumvented.

Description:
FIELD OF INVENTION 
     The disclosed invention relates to the use of radio frequency identification (“RFID”) tags to restrict people and objects within a designated perimeter, and more particularly to an RFID tag which transmits an alarm to the monitoring agency whenever the attached tag has been tampered with, severed, or otherwise circumvented. 
     BACKGROUND OF THE INVENTION 
     RFID tags can be used to control the movement of people within a designated perimeter. Examples of such use include infant or pediatrics patient protection in a care facility, elder-care wander prevention, or house arrest enforcement where a tagged person is restricted to a monitored area. Effective perimeter restriction is only possible if an alarm is generated when the tag is removed from a monitored person&#39;s body. 
     Existing RFID tag-bands employ a variety of methods to maintain continuity, including embedding conductive traces within or through the band, using a band made entirely of electrically conductive material, optical signal transmission through the optically conductive band, optically conductive fiber(s) embedded within the band, and electromagnetic or capacitive coupling between the band and the tag. 
     Presently, detection of RFID tag band removal is done by monitoring conductivity of the following electrical current path: A current source within the RFID tag initiates electrical current flow from a metal contact to the outside of the RFID tag enclosure; A mechanical bond is made between metallic contact and an electrically conductive band made out of flexible material with embedded metal conductors; The mechanical bond is semi-secure with intention to reliably maintain electrical contact during normal use; On the other side of the band, there is another metal contact on tag&#39;s enclosure which enables electrical current to enter the enclosure and be detected by electronic circuitry. 
     Any break in electrically conductive path is considered a breach in tag attachment and Tamper Alarm is declared. This conductive path break can come from the band being cut or from detachment between the band and the metal contacts on the tag enclosure. Band cut is always a legitimate cause for signalling tamper alarm, but interruption in electrical current flow between the tag enclosure contacts and the band can occur not only due to physical detachment between the contact and the band, but also due to decreased conductivity which can, and frequently does, occur due to oxidation of metallic contacts or unreliable bond between the contacts and the metallic conductors within the band. The oxidation occurs as a result of cleaning the tag body after every use, usually with aggressive solutions. This is the cause of many false Tamper Alarms. 
     Some cut-band RFID tags are based on the principle of detecting conductivity of the band surface or conductivity of the band itself (when the entire band is made out of electrically conductive material). In this case, there is a potential for defeating the capability of the tag to detect when the band is being cut by a jumper wire with 2 alligator clips on each end of the wire and clamping alligator clips to the band in a way that they make conductive contact with exposed and conductive parts of the band. In such a case “alligator clip wire” creates a shunt for electrical current and if the band is cut between two alligator clips, the tag can be removed from the person, without detection that the band is cut because the current continues to flow through the alligator clip wire. This is a potential security breach which can be very easily exploited on some bands, that is desirable to eliminate. 
     Present cut-band RFID tag devices using embedded conductive materials (fibers, traces) are often prone to false alarms due to open circuits caused by normal user wear. What is needed is a cut-band tamper-signalling RFID tag which allows for robust movement of the band and band to tag connection without triggering false alarms, while maintaining the electrical integrity of the device from tampering and attempts to circumvent or remove. Additionally, there are maintenance issues with pre-existing RFID conductive band tags. It would be useful to be able to re-use expensive RFID elements while readily disposing, for hygenic reasons, of conductive band portions that have been used for a designated duration of time on a patient. 
     SUMMARY OF THE INVENTION 
     The Anti-tamper Conductive Plastic Band for RFID Tag of the present invention is designed to provide: a device which allows non-restrictive movement of the band and band to tag connection when secured around a wrist or ankle; more robust electrical contact with the tag and continuity around the band; initiation of the tamper alarm if movement is too extreme or attempts are made to circumvent continuity, and significant immunity to “alligator-clip” type and related attacks after the band is secured to the tag. 
     For the purposes of this invention, reliable detection of current flow interruption is the technology where important improvements are made. These include the shape of the contact within a tag holder loop, the use of conductive plastic embedded within a robust rubber banded tag holder, and anti-tamper elements within the band to tag contact area. The disclosed invention provides a more reliable method of detecting if the band has been cut or loosened so that the tag can be removed from the person, while preventing false triggering and continuity failures due to its more robust design. 
     Essentially the invention provides an electrically conductive band for an RFID tag having: 
     a) an RFID tag enclosure; 
     b) an electrical continuity contact within a loop on an end of the electrically conductive band; 
     c) an electrically conductive landing area on a tongue of the band; 
     the tongue being insertable through the loop to secure the band around a body to be monitored by an RFID system, the tongue thereby engaging a portion of the electrically conductive landing area with the electrical continuity contact. The electrically conductive landing area has a series of electrical continuity dimples in each of which there is an electrical contact to an electrical pathway around the electrically conductive band. A preferred structure for the electrical contact within the loop is a pin, shaped to fit within a continuity dimple in the electrically conductive landing area on the tongue. Preferably, the tongue additionally has a series of anti-tamper dimples and the loop has an anti-tamper pin shaped to fit within an anti-tamper dimple in the tongue. The anti-tamper dimples can be arranged as a series of pairs of anti-tamper dimples, with an electrical continuity dimple between each pair, the loop having a corresponding pair of anti-tamper pins, with an electrical continuity pin between the pair of anti-tamper pins. 
     The loop and the tongue thereby have an interlocking structure of pins and dimples respectively with one-way bevels to form a ratchet mechanism during attachment of the electrically conductive band to an object or a patient, in order to allow easy attachment yet prevent accidental loosening of the band once when it is attached. There should be such one-way (zip-tie principle) bevels for both the anti-tamper pin and corresponding anti-tamper dimples, and the electrical continuity pin and corresponding electrical continuity dimples. 
     In the electrically conductive band, the RFID tag holder has a loop electrical contact and a band tag contact. A fitting RFID tag would have a complementary couple of RFID electrical contacts each joined with an electrical current detector in the RFID tag. The couple of RFID electrical contacts are located on the RFID tag such that when the RFID tag is inserted in the RFID holder, the RFID electrical contacts make electrical contact with the loop tag electrical contact and the band tag contact respectively. By this means, an electrically conductive circuit is formed when the RFID tag is placed in the RFID holder and the electrically conductive band is attached to a patient or an object by having the tongue passed through the loop—the electrical current detector senses a lack of continuity when the RFID tag is removed from the RFID tag holder causing the RFID tags to signal a tamper alarm condition. 
     The feature of having an RFID tag inserted within a tag holder which uses a conductive band to make electrical contact between one side of the holder to the other enables disposability of the conductive band and separate retention of the more valuable RFID tag. The complexity of band securement is removed from the RFID tag itself to the disposable conductive band. The RFID tag (which is typically intended to last 12 months) can be re-used with another conductive band. 
     It is a useful variant for the electrically conductive band to comprise an electrically conductive plastic core within a non-conductive shell, in order to prevent “alligator-clip” circumvention of tamper alarms. There should also be a non-conductive outer shell between electrically conductive dimples on the landing area of the tongue that causes an interruption of electrical current flow when the electrical continuity pin passes from one continuity dimple to another upon the band being loosened after attachment whereby the electrical current detector senses a lack of electrical continuity when the electrical continuity pin passes from one continuity dimple to another and signals a tamper alarm condition. 
     The RFID electrical contacts can be made of hard conductive plastic and shaped to provide a tight fit within the RFID holder and a water-proof transition between electronic circuitry inside the RFID tag and the tag enclosure. A middle portion of the length of the electrically conductive band can be made thinner than the end portions of the band, to provide flexibility and comfort of fit on a patient. The tongue portion at one end of the electrically conductive band, and the portion around and adjacent to the loop end of the band can be made of the same plastic, but wider and stronger than the middle portion, in order to ensure strength at the juncture and to ensure that the tongue and loop portions can endure the force required to insert the tongue portion through the (tight-tolerance) loop at the other end of the electrically conductive band. 
     The electrically conductive band has a curved section bending from the RFID tag holder to position the band closer to a patient&#39;s wrist to which the electrically conductive band may be attached. The RFID tag holder has an opening into which an RFID tag is placed prior to attachment to a patient&#39;s wrist, with the electrically conductive band and a base portion of the RFID holder thereby securing the RFID tag within the holder and against the patient wrist after attachment of the electrically conductive band and around a patient&#39;s wrist. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1 a    shows a top isometric view of a banded tag holder and the band. 
         FIG. 1 b    shows a bottom isometric view of a banded tag holder and the band with its RFID tag enclosure about to be inserted. 
         FIG. 1 c    shows a bottom close-up view of securement section dimples. 
         FIG. 2 a    shows a top view of a banded tag holder. 
         FIG. 2 b    shows a top close-up view of loop elements. 
         FIG. 2 c    shows a top view of conductive plastic core elements. 
         FIG. 3 a    shows a bottom view of a banded tag holder. 
         FIG. 3 b    shows a bottom close-up view of loop core elements. 
         FIG. 3 c    shows a bottom view of conductive plastic core elements. 
         FIG. 4 a    shows a bottom isometric close-up view of a tag holder with its mated RFID tag enclosure. 
         FIG. 4 b    shows a top isometric view of an RFID tag enclosure. 
         FIG. 5 a    shows an isometric view of the Anti-tamper Conductive Plastic Band for RFID Tag as worn. 
         FIG. 5 b    shows a close-up cutaway isometric view of a tag holder with its RFID tag enclosure inserted. 
         FIG. 6 a    shows a cutaway side view of a tag holder with its inserted RFID tag enclosure. 
         FIG. 6 b    shows a close-up cutaway side view of the loop region with its band inserted, and part of the PCB region. 
         FIG. 7 a    shows a top isometric view of the tag enclosure cap. 
         FIG. 7 b    shows a top isometric view of the PCB inserted into the tag enclosure base. (with battery). 
         FIG. 7 c    shows a top isometric view of the PCB inserted into the tag enclosure base. (without battery). 
         FIG. 7 d    shows a top isometric view of the tag enclosure base. 
         FIG. 7 e    shows a bottom isometric view of the PCB. 
         FIG. 7 f    shows a bottom isometric view of the tag enclosure base. 
         FIG. 8 a    shows a top isometric view of a PCB connected to fastened tag contacts. 
         FIG. 8 b    shows a top isometric view of a base with tag contact seats employed with fastened tag contacts. 
         FIG. 8 c    shows a side cutaway view of a PCB connected to fastened tag contacts. 
     
    
    
     DETAILED DESCRIPTION 
     All elements will now be introduced by reference to figures, then how each element functions and interacts with each other element will be described where relevant. 
       FIG. 1 a    shows a top isometric view of a banded tag holder  12  which is comprised of a band  14 , tag holder  28  and conductive plastic core  64 . (see  FIGS. 2 c    &amp;  3   c  for latter) These three elements are molded as one unit, but will be treated separately for clarity of discussion. The band  14  includes a curved section  16 , flange section  18 , securement section  20 , and tongue  26 . The curved section  16  pre-forms the band  14  to accommodate fitting around a wearer&#39;s appendage and to reduce mechanical stress. The flange section  18  provides a thicker portion of the band  14  that is less binding on the wearer when the securement section  20  is tightened as it is inserted through the loop  42 . The tongue  26  is the end portion of the band  14  that is first inserted into the loop  42  and is rounded for easier insertion and has raised projections on the top (see  FIG. 2 a   ) for easier gripping.  FIG. 1 b    shows a bottom isometric view of the banded tag holder  12  with its tag enclosure  44  about to be inserted into the cup  30  of the tag holder  28 . Shown here the tag enclosure  44  is comprised of a cap  46  and a base  48 .  FIG. 1 c    shows a bottom close-up view of the anti-tamper dimples  22  and continuity dimples  24  of the securement section  20  of the band  14 .  FIG. 1 c    also shows the internal band core  66  visible at the bottom of each continuity dimple  24 , part of the conductive plastic core  66  embedded inside the banded tag holder  12  as shown in  FIGS. 2 c    and  3   c.    
       FIG. 2 a    shows a top view of a banded tag holder  12 , while  FIG. 2 b    shows a top close-up view of loop  42  elements, including pawl arm  36 , anti-tamper pins  38  and continuity pin  40 . FIG.  2   c  shows a top view of the conductive plastic core elements  64 , including a band core  66 , band holder core  68 , loop holder core  70  and loop core  72 . 
       FIG. 3 a    shows a bottom view of a banded tag holder  12  with its cap receptacle  30 , band tag contact  32  and loop tag contact  34 .  FIG. 3 b    shows a bottom close-up view of loop core elements  72  shown in  FIG. 3 c   , including loop tag contact  34 , pawl arm  36 , anti-tamper pins  38  and continuity pin  40 .  FIG. 3 c    shows a bottom view of conductive plastic core  64  elements including band core  66 , band tag contact  32 , band holder core  68 , loop holder core  70 , and loop core  72 . 
       FIG. 4 a    shows a bottom isometric close-up view of a tag holder  28  with its mated tag enclosure  44  wherein the cap  46  fits into the cap receptacle  30 , the tag band contact  52  inserts into the band tag contact  32 , and the tag loop contact  50  inserts into the loop tag contact  34 .  FIG. 4 b    shows a top isometric view of the tag enclosure  44  and the unique shape of the cap  46  which permits ready tag enclosure  44  removal when required. 
       FIG. 5 a    shows an isometric view of the complete Anti-tamper Conductive Plastic Band for RFID Tag  10  as it might be worn, with the band  14  slotted through the loop  42  and secured by the internal pawl arm  36 .  FIG. 5 b    shows a close-up cutaway isometric view of a tag holder  28  with its inserted tag enclosure  44 , illustrating how the contacts mate as described in  FIG. 4 a   . For example, by means of the inserted contact pin  74 , the PCB  54  connects to the tag loop contact  50 , which slots into the loop tag contact  34 , which projects a pawl arm  36  with its anti-tamper pin  38  (and continuity pin  40  see  FIG. 3 c   ) into the loop  42 . 
       FIG. 6 a    shows a cutaway side view of a tag holder  28  with its inserted tag enclosure  44 , with  FIG. 6 b    showing a close-up cutaway side view of the loop  42  and PCB  54  region in  FIG. 6 a   . In this close-up view the securement section  20  of a band  14  is locked by the anti-tamper pin  38  of the pawl arm  36 . (and continuity pin  40  see  FIG. 3 c   ) Also shown is one method of electrically connecting the contact pin  74  of the tag loop contact  50 , by means of conducting adhesive  78  applied to the conductive contact pad  76  of the PCB  54 . 
       FIG. 7 a    shows a top isometric view of the tag enclosure cap  46  as it would mate with its base  48  in  FIG. 7 b   .  FIG. 7 b    shows a top isometric view of the PCB  54  inserted into the tag enclosure base  48  with a battery  62  and RFID antenna wire  86 .  FIG. 7 c    shows a top isometric view of the PCB  54  without the battery  62 , revealing the microcontroller  56  and current detector  58  integrated circuitry. Also shown is how the contact pin  74  fits into the PCB&#39;s contact pad  76 .  FIG. 7 d    shows a top isometric view of the tag enclosure base  48  and revealing the contact pins  74  as they align with the PCB  54  above.  FIG. 7 e    shows a bottom isometric view of the PCB  54 , exposing the RFID tag electronics  60 .  FIG. 7 f    shows a bottom isometric view of the tag enclosure base  48  and how its tag band contact  52  inserts into the contact pad  76  in the PCB  54  in  FIG. 7 e    above. 
       FIGS. 8 a  to 8 c    relate an alternate means to connect tag contacts to a PCB  54  and secure them to the base  48  of a tag enclosure  44 .  FIG. 8 a    shows a top isometric view of a PCB  54  connected to fastened tag contacts  80  by means of fasteners  84 .  FIG. 8 b    shows a top isometric view of a base  48  with the tag contact seats  82  employed with fastened tag contacts  80 , and in this view revealing fastener holes  88 .  FIG. 8 c    shows a side cutaway close-up view of a PCB  54  connected to contact pads  76  (see  FIGS. 7 c    &amp;  7   e ) by means of fasteners  84  screwed into each fastener hole  88  in fastened tag contacts  80 . Conducting adhesive  78  may also be used in each fastener hole  88  to increase continuity reliability and fastener  84  integrity in this critical connection. 
     The preferred embodiment of the Anti-tamper Conductive Plastic Band for RFID Tag will now be described in detail. 
     The disclosed Anti-tamper Conductive Plastic Band for RFID Tag  10  employs a conductive plastic core  64  as contacts to the tag enclosure  44 , as the conductive portion of the band  14 , and as contacts within the tag holder  28  loop  42 . (see  FIGS. 1 b  to 3 c   ) Conductive plastic has the flexibility and durability of plastic (polyethylene), but instead of acting as an electrical insulator, it can conduct electrical current when enriched with carbon or another material with similar conductive properties. Note that the conductive plastic of the band &amp; loop tag contacts ( 32  &amp;  34 ), pawl arm  36  and pins ( 38  &amp;  40 ) can be both thicker and/or of higher strength (stiffer) composition than the conductive plastics material which forms the thinner portion  66   a  of the band core  66  (see  FIGS. 3 a  to 3 c   ). This is to ensure that the band  14  is flexible and soft enough for comfortable wear, while at the same time ensuring the tag contacts are strong enough to make durable and reliable electrical contact. Fully sealed transition between the electronic circuitry inside the tag enclosure and outside of the tag enclosure which can be ensured by an over-moulding injection process where two different plastic materials are used to create a) a relatively hard RFID tag holder for a tight fit with an RFID tag and a hard tongue portion for ease of insertion in the loop, and b) a softer middle portion of the electrically conductive band for comfort and flexibility of fit around a wrist on a patient. 
     The electrical continuity path that ensures the integrity of the Anti-tamper Conductive Plastic Band for RFID Tag will now be discussed. As shown in  FIGS. 5 b    &amp;  7   b , the tag enclosure  44  houses a PCB  54 , from which a battery  62  generates electrical current to the tag contacts ( 50  &amp;  52 ). Tag contacts are embedded into the base  48  of the tag enclosure  44  by means of an over-moulding plastics injection process. The PCB  54  is then placed into the base  48  of the tag enclosure  44  and each tag contact is secured and electrically connected to the PCB  54  with conducting adhesive  78  or by a screw fastener  84  threaded into the hole  88 . After installing a cap  46  onto the base  48  the tag enclosure  44  is closed and fully sealed (see  FIGS. 7 a , 7 b   , &amp;  4   b ). By inserting the tag enclosure  44  into the cap receptacle  30  (see  FIGS. 4 a    &amp;  6   a ), electrical connection between the tag holder  28  and the tag contacts is accomplished. 
     The current source from the battery  62  inside the tag enclosure  44  is now available at the band tag contact  32 . The loop tag contact  34  is connected to an electrical current detector  58  with an analog to digital converter. Both the battery  62  and current detector  58  are controlled by a microcontroller  56 . (see  FIG. 7 c   ) The microcontroller  56  monitors and controls how the current generated by the battery  62  is detected by the current detector  58 . When the tongue  26  of the band  14  is inserted into the loop  42 , and the securement section  20  engages the pawl arm  36 , its protective anti-tamper pins  38  seat into the band&#39;s anti-tamper dimples  22 , while the protected continuity pin  40  seats into the continuity dimple  24 . Current flows from the conductive plastic band core  66  at the bottom of the continuity dimple  24 , through the continuity pin  40 , down the pawl arm  36 , from the loop tag contact  34  to the tag loop contact  50 , and by means of the contact pin  74  or the screw  84 , back to the PCB  54 . By this means the current is detected and the circuit is completed and the Anti-tamper Conductive Plastic Band for RFID Tag  10  is armed. If the conductive plastic core  64  of the band  14  is severed, or the continuity pin  40  is disconnected from the continuity dimple  22 , even momentarily as might happen in a jumper attack, the tamper alarm would be activated. 
     The shape of the pins projecting from the pawl arm  36  and the shape of the dimples on the band where these pins make contact are designed to make a reliable and firm physical connection between the band  14  and the tag holder  28 . This connection prevents the band  14  from being loosening once it is fastened onto the patient and also ensures reliable electrical contact. The shape of the contacts within the loop  42  of the tag holder  28  also permit limited pivoting of the band  14  portion closest to the loop  42  so that the wearer will not create false alarms by merely adjusting the Anti-tamper Conductive Plastic Band for RFID Tag  10  for comfort. This is made possible by a central continuity pin  40  projecting from a flexible pawl arm  36 , as well as the elongated dimples in the securement section  20  of the band  14 . (see  FIG. 1 c   ) 
     The banded tag holder  12  is made by means of an over-moulding process, whereby the conductive plastic inner core  64  of the band  14  is over-moulded with a rubberized material which provides electrical insulation and mechanical support. This support means that the conductive plastics may be relatively thin and narrow so as to allow for the greater mechanical flexibility necessary for comfortable wear. Partial covering of the conductive portion of the band  14  ensures better protection against the “alligator clip attack” described earlier, which is the weakness of similar products currently available. 
     Another advantage of embedding conductive plastics within a rubber shell is the increased security from tamper attacks. Notice that the continuity pin  40  is protected by an anti-tamper pin  38  on each side of the pawl arm  36 , as well as by the fact that it is protected by the surrounding rubber shell material around each dimple. If one were to attempt to jumper around the continuity pin  40 , one would have to force their way through the flanking anti-tamper pins  38  and the rubber band material, and in the attempt the disconnection would be detected by the current detector and the tamper alarm triggered. 
     An alternate embodiment of the Anti-tamper Conductive Plastic Band for RFID Tag includes a different method of attaching tag contacts to the PCB  54 . As shown in  FIGS. 8 a  to 8 c   , a fastened tag contact  80  is over-molded into a tag contact seat  82  in the base  48 . Then a fastener  84  may be used to secure the PCB  54  into the fastener hole  88  in said contact  80 . The fastener  84  creates electrical contact between the contact pad  76  (see  FIG. 7 c   ) of the PCB  54  and the fastener hole  88  of the fastened tag contact  80 . A conducting adhesive  78  may also be used to improve both electrical and mechanical contact. Other embodiments are not ruled out or similar methods leading to the same result. 
     Other advantages of using the Anti-tamper Conductive Plastic Band for RFID Tag  10  over other methods or devices will now be described. The use of hard conductive plastics as a material for tag contacts ensures a fully sealed connection between the electronic circuitry inside the tag enclosure  44  and the conductive plastic band &amp; loop contacts embedded in the rubberized tag holder  28  surrounding the tag enclosure  44 . This prevents the ingress of water in the region where the metallic PCB contacts and the tag holder  28  contacts meet, a hazard which occurs in existing cut-band RFID tag designs which utilize metallic PCB contacts. The present invention also eliminates the problem created by corrosion of metallic contacts which occur due to use of corrosive medical solvents to clean the tag after every use. The corrosion creates unreliable electrical connection due to the oxide layer created, whereas conductive plastic materials cannot corrode. 
     The use of soft conductive plastic materials the RFID tag band and the tag holder provides the following benefits, namely the conductive portion of the band can be fully embedded within the non-conductive, rubberized outer shell, thereby preventing “alligator clip attack” by controlling [reducing] the size and position of openings where the contact between the band and the tag holder is made. The band should be made thinner in a middle portion of its length in order to increase its overall flexibility and comfort around a patient&#39;s wrist, and thicker toward each of its ends in order to ensure the tongue can be inserted through the loop and to provide additional strength where attached via the tongue and loop. The design of the loop and pawl pins allows for limited movement without false triggers, yet still prevents tamper attempts. 
     The shape of the contact within a tag holder loop and the shape of the landing area on the band which is being inserted through the loop can such as to allow easy movement of the band end through the loop in one direction (inserting the band into the loop), but more difficult movement in opposite direction (this is “zip-tie effect”). One zip-tie shape that accomplishes this effect is to have a bevel on the tonque-insertion (leading) side of the pawl pin or tab within the receiving loop, but a right-angle edge on the distal side of the pawl pin or tab. The bevels could alternatively be on a non-leading side only of each dimple or slot structure, as shown in the continuity dimple  24  in  FIG. 1 c    for example. This “one-way beveling” results in a ratchet mechanism that is embodied not only in the continuity pins/tabs and corresponding dimples/slots, but also in the anti-tamper pins/tabs and corresponding anti-tamper dimples/slots. It allows ease of attachment, but once the pin/tab has caught in any particular corresponding dimple/slot on the tongue, it is more difficult to pull the tongue back out of the loop. When applied to the present invention, this prevents accidental loosening of the band once when it is applied on the patient. Even though the movement of the band in opposite direction is difficult, it is still possible (when band loosening is absolutely required) if the appropriate force is applied. When the band is being loosened there is an interruption of current flow while the loop contact is moving from the one landing area on the band to the other, as the loop contact has to travel over rubberized outer shell which is not conductive. Firm connection between the loop contact and the conductive portion of the band ensures reliable electrical connection. This is achieved by the shape of loop contact and the shape of the loop which are both flexible and designed to allow movement as the band moves into the loop. The movement allows the band to move in at the expense of the increased pressure on the band. This increased pressure creates increase in contact reliability. 
     The foregoing description of the preferred apparatus and method of installation should be considered as illustrative only, and not limiting. Other forming techniques and other materials may be employed towards similar ends. For example, the anti-tamper pin could be tab-shaped and the complementary anti-tamper dimples could be correspondingly slot-shaped to receive and fit the anti-tamper pin. Likewise the electrical continuity pin could be tab-shaped and the complementary continuity dimples could be correspondingly slot-shaped to receive and fit the continuity pin. It would be also be a functional equivalent to have the anti-tamper dimple in the loop, with a series of anti-tamper pins on the tongue. Again, interlocking ribs could be used instead of tabs and slots. These would all be functional equivalents for the locking and electrical interaction between the tongue and loop. Likewise, it would be a functional equivalent to have an electrical continuity dimple in the loop and a series of electrical continuity pins on the tongue. Various other changes and modifications will occur to those skilled in the art, without departing from the true scope of the invention as defined in the above disclosure, and the following general claims.