Abstract:
According to a first aspect of the present disclosure, an electronic tamper detection device is provided, comprising a tamper loop and a deformable component, wherein a deformation of said component indicates that the tamper loop has been broken. According to a second aspect of the present disclosure, a corresponding method of producing a tamper detection device is conceived.

Description:
FIELD 
       [0001]    The present disclosure relates to an electronic tamper detection device. Furthermore, the present disclosure relates to a corresponding method of producing an electronic tamper detection device. 
       BACKGROUND 
       [0002]    Electronic tamper detection devices may be used to detect tampering with closed or sealed products, such as bottles, packets and other containers. For example, in the spirits industry and the pharmaceutical industry such tamper detection devices may be useful. Tamper detection devices often contain a so-called tamper loop. A tamper loop may for example comprise a conductive wire that is broken when a closure or seal in which it is concealed is broken. Frequently used tamper detection devices are radio frequency identification (RFID) or near field communication (NFC) tags comprising or extended with a tamper loop. It may be desirable to improve these tamper detection devices, so that more tamper attempts can be detected. 
       SUMMARY 
       [0003]    According to a first aspect of the present disclosure, an electronic tamper detection device is provided, comprising a tamper loop and a deformable component, wherein a deformation of said component indicates that the tamper loop has been broken. 
         [0004]    In one or more embodiments of the tamper detection device, the component is a piezoelectric or piezoceramic device. 
         [0005]    In one or more embodiments of the tamper detection device, the component forms an integral part of the tamper loop. 
         [0006]    In one or more embodiments of the tamper detection device, the tamper loop comprises a conductive wire. 
         [0007]    In one or more embodiments, the tamper detection device is configured to detect the deformation of the component by sensing a change in ohmic resistance resulting from said deformation. 
         [0008]    In one or more embodiments, the tamper detection device further comprises a sensing circuit configured to sense said change in ohmic resistance. 
         [0009]    In one or more embodiments of the tamper detection device, the sensing circuit is a strain gauge. 
         [0010]    In one or more embodiments, the tamper detection device is a passive RFID or NFC tag. 
         [0011]    In one or more embodiments, the tamper detection device is embedded in a closure or a seal. 
         [0012]    According to a second aspect of the present disclosure, a method of producing an electronic tamper detection device is conceived, wherein the tamper detection device is provided with a tamper loop and a deformable component, wherein a deformation of said component indicates that the tamper loop has been broken. 
         [0013]    In one or more embodiments of the method, the component is a piezoelectric or piezoceramic device. 
         [0014]    In one or more embodiments of the method, the component forms an integral part of the tamper loop. 
         [0015]    In one or more embodiments of the method, the tamper loop comprises a conductive wire. 
         [0016]    In one or more embodiments of the method, the tamper detection device is further provided with a sensing circuit configured to sense a change in ohmic resistance resulting from the deformation of the component. 
         [0017]    In one or more embodiments of the method, the sensing circuit is a strain gauge. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0018]    Embodiments will be described in more detail with reference to the appended drawings, in which: 
           [0019]      FIG. 1  shows an example of a tamper detection device; 
           [0020]      FIG. 2  shows an illustrative embodiment of a tamper detection device; 
           [0021]      FIG. 3  shows another illustrative embodiment of a tamper detection device; 
           [0022]      FIG. 4  shows an illustrative embodiment of a piezo-element. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0023]      FIG. 1  shows an example of an electronic tamper detection device  100 . In this example, the tamper detection device  100  is an RFID or NFC tag equipped with a tamper loop. The tag may be a so-called passive tag, i.e. a tag powered by an electromagnetic field generated by an external device (not shown). The tag comprises an integrated circuit  102  (i.e., a tag circuit) which is coupled through contact pads LA and LB to an antenna  104  for establishing wireless communication with said external device. The tamper loop is formed by a detection wire  106  (i.e., a conductive wire) which is coupled to the integrated circuit  102  through contact pads GND and DP. The detection wire  106  may for example be concealed in a closure comprising a pull linkage  108 . In operation, once the detection wire  106  (tamper loop) has been broken (e.g., at the pull linkage  108 ) and the tag is powered by said electromagnetic field, the tag can detect the “Open” information and act accordingly. As used herein, “Open” information refers to information indicative of an opened or broken tamper loop, while “Close” information refers to information indicative of a closed or unbroken tamper loop. 
         [0024]    Electric energy may be required for reading the state of the tamper loop. For example, in case the tamper loop comprises a conductive wire  106 , its state is normally read by generating a current that will flow (in case the wire is unbroken) or not flow (in case the wire is broken) from one contact pad to another. However, under some circumstances electric energy may not be available. For example, a passive RFID or NFC tag  100  has no internal power source and the tag&#39;s circuit  102  can only be powered by an electromagnetic field generated by an external device, which may or may not be in the tag&#39;s proximity. That is to say, a passive tag is typically unpowered for large periods of time. Then, if somebody breaks the tamper loop and repairs it while the tag circuit  102  is unpowered, the circuit  102  will not be able to detect that the tamper loop has been opened in the meantime. Consequently, some tamper attempts may remain undetected. Thus, it is desirable to improve the tamper detection device  100 , so that more tamper attempts can be detected. 
         [0025]    Therefore, in accordance with the present disclosure, an electronic tamper detection device is provided, comprising a tamper loop and a deformable component, wherein a deformation of said component indicates that the tamper loop has been broken. In particular, the deformation of said component represents the “Open” information. In this way, it is probable that the “Open” information is retained because the deformation of said component typically lasts longer than an unpowered state of a tag. Thus, tamper attempts occurring when a tag is unpowered, for example, may still be detected. 
         [0026]    In one or more embodiments, the component is a piezoelectric or piezoceramic device. A piezoelectric or piezoceramic device is particularly suitable as a deformable component of the kind set forth. A piezoelectric device may be made, for example, of a simple crystalline material. A piezoceramic device may be made of a composite material, such as barium titanate (BaTiO 3 ) or lead zirconate titanate (PZT). Usually these devices behave elastically (elastic deformation), but they also have a region where they behave plastically. This plastic deformation is caused by mechanical overstress. The plastic deformation of a piezoelectric or piezoceramic device is in practice a quasi-permanent deformation, because it is virtually impossible to undo it. From this perspective, the piezoelectric or piezoceramic device may be regarded as similar to a one-bit memory cell (i.e., a one-time programmable memory cell). The original state of the piezoelectric or piezoceramic device represents the “Close” information, and the deformed state represents the “Open” information. If somebody opens for instance a wine-bottle, he will cause an overstress on the piezoelectric or piezoceramic device by turning the closure; this yields the “Open” information by cutting off the tamper loop and by plastic deformation. The next time the RFID/NFC tag circuit is powered up, it detects that the tamper loop has been opened. Even if the tamper loop has been repaired, the tag circuit will read the “Open” information because the piezoelectric or piezoceramic device is quasi-permanently deformed. Due to the high forces necessary to plastically deform a piezoelectric or piezoceramic material, it is virtually impossible to bring it back to its original state. 
         [0027]    In one or more embodiments, the deformable component forms an integral part of the tamper loop. In this way, since the tamper loop is normally placed at a location where a tamper attempt may be expected, it is more likely that the component becomes subject to mechanical overstress in case of a tamper attempt. In a practical and efficient implementation, the component may be integrated with a conductive wire to form a single tamper loop. 
         [0028]      FIG. 2  shows an illustrative embodiment of a tamper detection device  200 . The tamper detection device  200  comprises an RFID or NFC tag circuit  202  coupled to a detection wire  204  through contact pads GND and DP. In particular, a voltage may be supplied to the detection wire  204  through contact pad DP (detection pad). Contact pad GND is a ground pad; alternatively another detection pad (not shown) may be used in case the measurement is not ground-based. Furthermore, the tag circuit  202  comprises contact pads LA and LB, for coupling the tag circuit  202  to an antenna (not shown) that may extract power from an electromagnetic field. Furthermore, the tag detection device  200  comprises a deformable component embodied as a piezo-element  206 . As used herein, the term “piezo-element” refers to a piezoelectric device or a piezoceramic device. In operation, the piezo-element  206  may transition from an initial state to a state of quasi-permanent deformation in response to mechanical strain or overstress caused by a tamper attempt. 
         [0029]      FIG. 3  shows another illustrative embodiment of a tamper detection device  300 . In this example, the piezo-element  302  is integrated with a sensing circuit, more specifically a strain gauge for measuring a change in ohmic resistance caused by the plastic deformation of the piezo-element  206 . 
         [0030]      FIG. 4  shows an illustrative embodiment of a piezo-element  400 . A practical and efficient way to detect a deformation, i.e. a constitutional change, of a piezoelectric or piezoceramic device is to measure the change of ohmic resistance caused by said change.  FIG. 4  shows how the ohmic resistance changes in dependence on a constitutional change of a piezo-element  400 . In its original state  402 , the ohmic resistance of the piezo-element  400  may be defined by: 
         [0000]    
       
         
           
             R 
             = 
             
               ρ 
                
               
                 L 
                 A 
               
             
           
         
       
     
         [0000]    Herein, variable R represents the ohmic resistance, constant ρ represents the electric resistivity of the material of which the piezo-element  400  is made, variable L represents the length of the piezo-element  400  and variable A represents the thickness of the piezo-element  400 . In its deformed state  404 , the ohmic resistance of the piezo-element  400  may now be defined by: 
         [0000]    
       
         
           
             
               Δ 
                
               
                   
               
                
               R 
             
             = 
             
               ρ 
                
               
                 ( 
                 
                   
                     
                       L 
                       + 
                       
                         Δ 
                          
                         
                             
                         
                          
                         L 
                       
                     
                     
                       A 
                       - 
                       
                         ( 
                         
                           
                             Δ1 
                              
                             
                                 
                             
                              
                             A 
                           
                           + 
                           
                             Δ2 
                              
                             
                                 
                             
                              
                             A 
                           
                         
                         ) 
                       
                     
                   
                   - 
                   
                     L 
                     A 
                   
                 
                 ) 
               
             
           
         
       
     
         [0000]    The resulting change of voltage may be defined by: 
         [0000]      Δ V=ΔR·I  
 
         [0000]    Herein, variable I represents the current driven through the piezo-element  400 . When the piezo-element is in its original state a calibration measurement may be done. This calibration measurement may be done by driving a current through the piezo-element, and taking the resulting measured voltage as a base value. In use, when performing a measurement after a plastic deformation of the piezo-element has taken place, another voltage level will be measured. Then, if the difference between the measured voltage level and the base value exceeds a predefined threshold, it may be concluded that the plastic deformation has taken place. The change of ohmic resistance caused by the constitutional change of the piezo-element may either be measured directly (as shown in  FIG. 2 ) or using a sensing circuit, e.g. a strain gauge (as shown in  FIG. 3 ). In case of a direct measurement, the piezo-element is conductive, so a voltage drop over the piezo-element can be measured directly after injecting a current from the detection pad DP to GND. In case of an indirect measurement, the carrier does not need to be conductive, and the measurement is done with a sensing circuit. The current may be supplied by the tag circuit  202  and may flow from one of the tamper contact pads through the detection wire  204  and the piezo-element  206 ,  302 , to the other of the tamper contact pads. Then, the voltage drop over the piezo-element  206 ,  302  may be evaluated and compared with an internal reference value (base value) indicating whether the piezo-element  206 ,  302 , is in the deformed state. The material of the detection wire  204  may be chosen such that it breaks only when the piezo-element  206 ,  302  has already been deformed plastically, so as to increase the reliability of the tamper detection device  200 ,  300 . 
         [0031]    It is noted that the embodiments above have been described with reference to different subject-matters. In particular, some embodiments may have been described with reference to method-type claims whereas other embodiments may have been described with reference to device-type claims. However, a person skilled in the art will gather from the above that, unless otherwise indicated, in addition to any combination of features belonging to one type of subject-matter also any combination of features relating to different subject-matters, in particular a combination of features of the method-type claims and features of the device-type claims, is considered to be disclosed with this document. 
         [0032]    Furthermore, it is noted that the drawings are schematic. In different drawings, similar or identical elements are provided with the same reference signs. Furthermore, it is noted that in an effort to provide a concise description of the illustrative embodiments, implementation details which fall into the customary practice of the skilled person may not have been described. It should be appreciated that in the development of any such implementation, as in any engineering or design project, numerous implementation-specific decisions must be made in order to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill. 
         [0033]    Finally, it is noted that the skilled person will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference sign placed between parentheses shall not be construed as limiting the claim. The word “comprise(s)” or “comprising” does not exclude the presence of elements or steps other than those listed in a claim. The word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. Measures recited in the claims may be implemented by means of hardware comprising several distinct elements and/or by means of a suitably programmed processor. In a device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. 
       LIST OF REFERENCE SIGNS 
       [0000]    
       
           100  tamper detection device 
           102  integrated circuit 
           104  antenna 
           106  detection wire 
           108  pull linkage 
           200  tamper detection device 
           202  RFID/NFC tag circuit 
           204  detection wire 
           206  piezo-element 
           300  tamper detection device 
           302  piezo-element (carrier) and strain gauge 
           400  piezo-element 
           402  original state 
           404  deformed state