Abstract:
An identification device includes an ultrasound transmitter unit and an outer housing which receives said transmitter unit, said outer housing including one or more apertures which are sealed by a membrane, said membrane being substantially transparent to ultrasound when compared to the rest of the housing.

Description:
[0001]    This application is a continuation of U.S. patent application Ser. No. 12/740,285 filed Oct. 7, 2010, which is entitled to the benefit of, and incorporates by reference essential subject matter disclosed in PCT Application No. PCT/GB2008/003658 filed on Oct. 28, 2008, which claims priority to Great Britain Patent Application No. 0721162.6 filed Oct. 29, 2007. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    This invention relates to identification devices which can be fitted to a person, animal or object to permit identification and/or real-time location tracking of the same. 
         [0004]    2. Background Information 
         [0005]    There is an important need in hospitals to he able to positively identify patients of the hospital to ensure that confidentiality is maintained and that the correct treatment is given. Conventionally this is achieved using single-use wrist bands on which identifying text, or occasionally a bar code, may be written or printed. There is a separate problem in many hospitals that the efficiency of staff and some common resources such as surgical theatres and emergency departments can be reduced if patients cannot be located at the appropriate time thus requiring staff to go looking for them and holding up other patients awaiting attention or therapy, or otherwise impeding an optimal workflow. There are also other patients for which there is a need to locate them for security reasons, for example if they should leave a ward unexpectedly such as new-born babies and elderly patients suffering from dementia. 
       SUMMARY OF THE INVENTION  
       [0006]    The Applicant has realized that the problems of identification and tracking can be addressed simultaneously by using ultrasonic identification. Thus, patients can be given individual active ultrasonic transmitters which can be used both for identification and tracking purposes. In particular, the applicant has devised such an identification device which is particularly suited to use in hospitals. adapted for human speech reception; and decoding said signal to determine said data. 
         [0007]    When viewed from a first aspect the invention provides an identification device comprising an ultrasound transmitter unit and an outer housing which receives said transmitter unit, said outer housing comprising one or more apertures which are sealed by a membrane, said membrane being substantially transparent to ultrasound when compared to the rest of the housing. 
         [0008]    Thus it will be seen by those skilled in the art that in accordance with the invention an active ultrasound transmitter, which will typically be of relatively high value, can be accommodated in an outer housing which can protect it from contamination by dirt, fluid and infection agents whilst still allowing ultrasound signals to pass from the transmitter. If contamination of the main transmitter unit can be prevented, it is then easy for it to be re-used without requiring sterilization which would be difficult to achieve in view of the sensitive electronics and transducers associated with it. The outer housing could be cleaned and sterilized between each use (as it does not contain the sensitive electronics), but preferably it is disposable. It can be seen therefore that the benefits afforded by an ultrasonic identification and tracking system can be enjoyed whilst minimizing the cost thereof allowing reuse of the transmitter units by utilizing a relatively inexpensive disposable part which obviates the need for cleaning/sterilization and minimizes the risk of cross infection. 
         [0009]    Although not essential, the membrane will typically be much thinner than the rest of the housing and/or of a different material. It is not necessarily essential that the membrane provides a hermetic seal. For example it is envisaged that it would be possible for it to comprise a sufficiently fine foam or mesh. However, in preferred embodiments a liquid-tight seal across at least the aperture(s) is provided. In preferred embodiments the membrane comprises a polymer film such as PVC, polyurethane or polyethylene. Preferably the film has a thickness of less than 50 μm, more preferably less than 20 μm and most preferably of the order of 10 μm. Such films (commonly known as cling film) are commonly and inexpensively available as they are used for wrapping and packaging food and other items. 
         [0010]    The membrane preferably attenuates ultrasound at 40 kHz by less than 6 decibels (dB), preferably less then 3 dB. 
         [0011]    In one of the important applications of the invention envisaged, the identification device will typically be fitted to a patient. The device could be worn around the neck, on clothing etc. Preferred embodiments however incorporate means for attaching the device to the body of a person. This could, for example, comprise an integral wrist or ankle strap. Equally however, in one set of preferred embodiments, the device comprises means for attaching it to an existing wrist strap. This is attractive since it means that conventional wrist straps can continue to be used to give a familiar visual identification, but since such straps are not easily removable and the preferred identification device is not easily removable from the strap, it is easy to ensure that patients keep their identification devices on. The strap, whether integral or separate, preferably comprises a one-way catch, as is well known for conventional hospital wrist hands, which allows the strap to be snapped closed but which cannot be re-opened without irreparably breaking the catch or cutting the strap which requires either a tool or very high degree of force. Similarly where the outer housing is adapted to be attached to a separate wrist band or the like, this attachment is also preferably configured so as to be single-use so that the device cannot be easily removed and cannot be re-used (thereby carrying a risk of cross-infection). 
         [0012]    Such an arrangement as is described above is considered to be novel and inventive in its own right and thus when viewed from a further aspect the invention provides an identification device comprising a transmitter unit received in an outer housing, the outer housing comprising a single-use attachment means for attaching the device to a wrist strap. Where the outer housing has means for attaching to a separate wrist strap in accordance with any aspect of the invention this is preferably configured to allow attachment when the strap is being worn by a patient. In some preferred examples of this the attachment means comprises a flap adapted to slide between the strap and the patient in order to clamp the strap between said flap and the body of the outer housing. 
         [0013]    The outer housing is preferably configured so that the transmitter unit can be sealed into it before attachment to a patient or patient&#39;s strap. This minimizes the risk of contamination entering the interior of the housing. The housing is preferably closed by a single-use catch which, once broken to allow release, cannot be re-used. Such an arrangement makes the device difficult to remove without special tools and also prevents inadvertent or deliberate re-use of potentially contaminated outer housings. 
         [0014]    Whilst there is clearly an important application of the principles of the invention to identifying and tracking patients in the hospital, the invention is not limited to this application and indeed it is envisaged that there are many other applications which would benefit from the identification devices as described above. For example, they could be used with humans in other situations—e.g. prisons, or with livestock or other animals in farms, zoos, veterinary practices or the like. Furthermore, the applicant has appreciated that similar considerations to those described above in the context of hospital patients, apply to hospital equipment, hospital staff members and hospital visitors; and it is also envisaged that such identification devices can therefore be used with these. 
         [0015]    The power source to the transmitter unit could be provided internally within the transmitter unit or, conceivably, externally of the whole device. However, the applicant has appreciated that in a particularly beneficial set of embodiments, a battery is provided within the outer housing such that it can be connected to the transmitter unit when the latter is inserted in the housing. This is beneficial since it means that the battery can be discarded along with the outer housing when each patient has finished using the device, thus ensuring that a fresh battery is available for each new patient. It also means that the transmitter unit itself does not need its own, longer life battery which saves on costs. 
         [0016]    The battery may be integral to the outer housing for simplicity, or it could he removable for recharging/recycling. Preferably the battery is so arranged within the outer housing that connection between it and the transmitter unit is made automatically upon installation of the latter. 
         [0017]    The arrangements set out above are considered to be novel and inventive in their own right and thus when viewed from a further aspect the invention provides a portable identification device comprising a transmitter unit and a battery for the transmitter unit which are received separately in an outer housing so that the transmitter unit can be removed from or installed into the outer housing independently of the battery. 
         [0018]    The transmitter unit is preferably an ultrasonic transmitter unit and the outer housing preferably has the aperture and membrane specified in accordance with the first aspect of the invention. The preferred features of the first aspect of the invention are, where appropriate, also preferred features of the above aspect of the invention. 
         [0019]    In accordance with each of the foregoing aspects of the invention it is preferred that the transmitter unit also comprises means for receiving a signal. This could be an ultrasound, radio frequency or infrared signal for example and is not limited to the type of signal which the transmitter transmits. However, in the presently preferred embodiments of the invention, the receiving means is an ultrasonic receiving means. 
         [0020]    It is recognized that, depending on how identification devices as described above are used in practice, a device could be powered for a significant period of time whilst it is in stock waiting to be used. One solution to this might be not to assemble either transmitter units or batteries into the device until it is ready to be used, but this may not be practical. Alternatively therefore in at least some preferred embodiments the identification device is configured so as to enable it to be activated when it is required for use. This could consist simply of an on/off switch, although this is not preferred since it is not considered desirable to allow patients or other users to be able to switch the devices off. Various arrangements are envisaged whereby a mechanical single-use on switch could be provided, for example by providing a removable insulating tab in the electrical path between the battery and the transmitter unit, or by a part that can be broken off/deformed to allow electrical contact to be made. However, these options are presently unattractive for various reasons such as potentially compromising the barrier provided by the outer housing and/or adding to the cost of the device, particularly the outer housing. 
         [0021]    In preferred embodiments of the invention the transmitter unit is adapted so that it can be activated upon receipt of a suitable signal, preferably an ultrasonic signal. Preferably the transmitter unit is configured to have at least two modes: a sleep or standby mode, in which it is simply receptive to the aforementioned signal; and an active mode into which the transmitter unit is switched upon receipt of the activation signal and in which the transmitter unit can or does transmit signals. In such an arrangement the sleep mode can be, and is preferably, configured so that there is very low power consumption compared to the active mode. This allows battery life to be extended whilst the device is not being used. 
         [0022]    The activating signal could be any chosen signal although in accordance with preferred embodiments the signal is at a significantly higher power than other signals received by the device or signals transmitted by the device. This is easily achievable since such a signal will only be required relatively infrequently and can be transmitted from a transmitter placed in very close proximity to the identification device. The device might, for example, be placed in a docking station or a handheld transmitter could be placed next to or on top of the device. Another advantage of utilizing a very strong activation signal is that the requirement for amplification and/or processing of the signal is reduced which reduces the power requirement for the sleep state. 
         [0023]    In preferred embodiments of the invention the transmitter unit can receive configuration information encoded on a suitable wireless signal. Again, it is preferred that this is an ultrasound signal. This configuration information could be received as part of the activation signal, although it is preferred that it is separate for the reasons given above. The configuration information would typically include the identification information which the transmitter unit is to give once in use for a particular patient. It might also include, for example, status codes associated with that patient associated with either the identification or tracking function of the device. For example, an identification device being configured for a new-born baby or an elderly patient might contain a flag to generate an alarm if the device is taken outside a pre-designated ward. As well as or instead of configuration information, the transmitter unit might receive other data such as new or updated software. 
         [0024]    Similarly the transmitter unit can, in some embodiments, transmit as well as receive information during a configuration or commissioning process. It might for example transmit identity information such as a serial number. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: 
           [0026]      FIG. 1  is a view of an identification tag embodying the invention prior to its attachment to a patient wrist strap; 
           [0027]      FIG. 2  is a view of the tag attached to a wrist strap; 
           [0028]      FIG. 3A  is a view from above of the internal structure of the tag body; 
           [0029]      FIG. 3B  is an exploded view from above of the internal structure of the tag body; 
           [0030]      FIG. 4  is an exploded view from below; and 
           [0031]      FIG. 5  is a view from beneath of the tag upper body shell. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0032]      FIG. 1  shows an ultrasonic identification tag for identifying, and/or tracking the movements of, a patient in a hospital. The embodiment described herein has been developed so as to be particularly suitable for this application, although the skilled person will appreciate that the principles embodied may find useful application in a wide variety of uses. 
         [0033]    The tag comprises two main parts which are a main body portion  2  and a hinged flap portion  4 . The flap portion  4  is molded integrally with the upper body shell  6  to form a so-called living hinge (not shown). On the upper face (as seen in  FIG. 1 ) of the flap portion  4  are formed a series of rounded protrusions  8 . This will be the part of the tag which presses against the patient&#39;s skin and the bumps  8  help to prevent it slipping and make it more comfortable for the patient to wear for a prolonged period of time without causing skin irritations or reactions. The material of the outer shell is biodegradable or recyclable and is non-abrasive against skin. 
         [0034]    At the distal edge of the flap portion  4  is a pair of integrally molded, downwardly extending hooks  10  (one of which can be seen in  FIG. 1 ) which are positioned so as to engage in corresponding half-moon apertures  12  formed in the front face of the upper body shell  6  when the flap  4  is closed around under the bottom of the main body portion  2 . This can be seen in  FIG. 2 . As the flap is closed, a wrist strap  14  can be sandwiched between the bottom of the main body portion  2  and the flap portion  4 . The hooks  10  engage in the apertures  12  in the upper body shell  6  thereby firmly securing the tag to the wrist strap  14 . The hooks  10  are very stiff and make a tight fit in the apertures  12  such that they cannot easily be removed without use of a special tool. 
         [0035]      FIGS. 3   a ,  3   b ,  4  and  5  show exploded views of the main body portion  2  of the tag. in  FIGS. 3   a ,  3   b  and  4  the flap portion of the tag has been omitted for clarity. At the heart of the main body portion  2  is a tag kernel  16  shown in  FIG. 3   a  and in exploded view in  FIG. 3   b . The tag kernel  16  has inside it a printed circuit board  16  which carries the components for an ultrasound transmitter unit. These include an ultrasound transducer  40 , a pair of inductors  42  and a crystal  44 . It may also be seen that there is an approximately square aperture  46  on two sides of which lie a pair of resilient electrical contact tabs  48 . These make contact with batteries when the tag is assembled as will be described later. 
         [0036]    The tag kernel  16  is completed by a lower kernel molding  20  and an upper kernel molding  22 . The lower kernel molding  20  carries three vertically projecting pins  50  which engage in corresponding cylindrical bosses  52  in the upper kernel molding (only one of which is visible in  FIG. 3   b ). This allows the circuit board  18  to be sandwiched between the upper and lower kernel moldings  20 ,  22 . The upper kernel molding is shaped at the front to frame the ultrasound transducer  40  as can be seen in  FIG. 3   a ; and is provided with an aperture  54  at the top in alignment with the aperture  46  in the circuit board. 
         [0037]    The vertical pins  50  and bosses  52  are configured so that they form a tight interference fit when the tag kernel  16  is assembled at the factory such that it is difficult or impossible to dismantle remove manually. Glue can be used as well or instead. This creates a robust, self-contained unit  16 . 
         [0038]    As will be appreciated from the foregoing, the tag kernel  16  cannot itself operate as an ultrasound transmitter or receiver as it does not have any batteries. These are inserted automatically when the complete tag is assembled by placing the kernel  16  into the upper body shell  6  as shown in  FIG. 4 . As the kernel  16  is pressed up into the upper body shell  6 , the two contact tabs  48  on the circuit board inside it engage the positive and negative sides respectively of a pair of button cell batteries  28  which are held in a plastic retaining clip molding  30  on the inside of the upper body shell  6 . This can be seen in  FIG. 5 . Thus as the kernel  16  is inserted into the upper body shell  6  from beneath, the batteries  28  partly protrude through the apertures  54 ,  46  in the upper kernel molding and circuit board respectively and the two contacts  26  make electrical connection with them in order to power the circuit. When power is applied to the circuit in this way, it enters a sleep mode which has a very low quiescent current of the order of 1 μA. In this mode the transmitter unit simply awaits an activation signal. 
         [0039]    It will also be seen that as the kernel  16  is pressed into the upper body shell  6 , the ultrasonic transducer  40  will be positioned directly behind a grille  32  formed on the front face of the upper body shell. The inwardly facing side of the grille  32  is visible in  FIG. 5 . Although omitted for clarity, in practice there is an impermeable membrane comprising a thin PVC film (approx. 10 microns) stretched across the bezel  34  around the rear face of the grille  32  to provide a hermetic seal. 
         [0040]    The bezel  34  and battery clips  30  are both molded as part of the upper body shell  6  in an inner portion  36  defined by an annular vertically protruding wall  38  the purpose of which will be described below. 
         [0041]    Returning to  FIG. 4  it can be seen that when the tag kernel  16  has been placed inside the upper body shell  6 , it is held in place by a sealing cap  56 . The diameter of the cap  56  is designed so that it is a tight fit around the outer circumference of the annular wall  38  on the inside of the upper body shell  6 . It will be appreciated that by virtue of this arrangement, the active components such as the transducer  18  etc. are retained within a sealed compartment formed inside the tag. The tag is then in the state shown in FIG.  1 —i.e. ready to be clamped onto a wrist band for use. 
         [0042]    As previously described, when the tag is needed the main body portion  2  can be placed on top of a patient wrist strap  14  as is shown in  FIG. 2 . The flap portion  4  is then folded over underneath the strap and clipped onto the bottom of the main body portion  2  so as to trap the strap  14  between them. This permanently attaches the identification tag to the strap  14 . The strap can now be attached to a patient in a known manner. If the patient is already wearing the strap, the tag is attached by first sliding the flap portion  4  underneath the strap and then folding the main body portion  2  down onto it. 
         [0043]    Either before or after it is fitted to the patient the transmitter unit is placed into an active (“wake up”) state by applying a very short-range, high-energy burst of ultrasound which is detected by the transducer. After wake-up there is the possibility of two-way ultrasound communication. This ultrasound communication can for example include: software download or configuration settings to the tag; and/or read-back of serial number, unique identification, software version or configuration information to the tag. These signals may be provided/received by a docking station, base station or hand-held transceiver, for example. 
         [0044]    After wake-up and configuration, the tag then transmits its identification information at periodic intervals and/or when interrogated by a base station until the tag is no longer required for that patient—e.g. until the patient is discharged—or until the battery is exhausted. The battery is designed to last approximately thirty days. The tag is preferably arranged to transmit a low battery message as it nears the end of the life of the battery so that a fresh tag can be configured for the patient if one is still required. 
         [0045]    When a tag is no longer required for a particular patient the wrist strap  14  is cut to release it from the patient&#39;s wrist or the single-use catch is broken. The tag can not therefore be fitted to another patient. The main body portion  2  is then removed from the strap  18 , again by forcibly prising the flap  4  away from the main body  2  using a suitable tool. This inevitably damages the connection between the flap  4  and the upper body shell  6  (for example by snapping the hook clips  10 ) so that they cannot be fitted back together. Finally the sealing cover  56  is removed which allows the tag kernel  16  to be removed. Removal of the kernel automatically disconnects it from the batteries  28  which remain in the clips  30  in the upper body shell  6 . The transmitter unit then loses its configuration information and will automatically return to sleep mode when it is next powered. It is therefore ready simply to be used again. Optionally but preferably an ultrasound receiver may be used in the vicinity of an area where tags are decommissioned. This can be used to detect the sudden cessation of transmission from a particular tag as it&#39;s kernel is removed from its battery and interpret this as a special event signifying that a tag is no longer being used. This can be communicated to a central database to allow immediate reallocation of resources (e.g. a bed) to a new patient. 
         [0046]    Since the transmitter unit has been protected in a sealed environment inside the tag (formed between the sealing cap  56 , the annular wall  38  and the film across the grille  32  and will be so again when it is next used, there is no need to clean or sterilize it before its next use. However if desired as a precaution, it can be treated by a plasma or radical-based process for example. This might be ordered for example only if it was noticed during decommissioning that the membrane had been ruptured or if decommissioning was carried out carelessly such that the transmitter unit was allowed to contact the exterior of the outer housing. Otherwise the kernel is placed in a separate receptacle for re-use. 
         [0047]    The batteries are removed from the upper body shell  6  by snapping the frangible clips  30  and are placed in a second receptacle to be industrially recycled. The upper body shell,  6 , strap  18  and sealing cap  56  are placed in a third receptacle and can also be sent for suitable material recycling if such is available which can cope with medically contaminated materials. 
         [0048]    The decommissioning process set out above can easily be achieved by an automated tool which causes the appropriate parts to fall into separate gins (e.g. kernels, batteries and contaminated materials). 
         [0049]    It will be apparent to those skilled in the art that the foregoing detailed description is merely one possible implementation and that there are many other possible implementations of the various principles set out herein. For example it is not essential that the transmitter unit is based on ultrasound, nor that it can receive as well as transmit. Other means of attachment to the target could be employed and the battery or other power source need not be separate to the transmitter unit.