This application is a 371 U.S. National Application of PCT/EP2013/072898, filed on Nov. 4, 2013, which claims priority to European Patent Application Nos. 12191829.6, filed on Nov. 8, 2012, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The invention relates to a needle magnetizing arrangement. 
     BACKGROUND OF THE INVENTION 
     In a conventional injection procedure, a user is generally advised to use a new injection needle or syringe for each injection to reduce a risk of cross contamination, infection and/or pain (e.g., when re-using blunt needles). However, the user may forget to change the needle or syringe before an injection thus subjecting themselves to the risks. 
     Some conventional injection devices utilize color coding to distinguish between used and unused injection needles and/or syringes. However, typically such color coding is in a small space on the injection device and can be difficult to see, especially for users with vision impairments. 
     In order to avoid these risks and overcome the problems associated with prior injection devices, there remains a need for a needle safety device, such as a needle magnetizing arrangement. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a needle magnetizing arrangement. 
     In an exemplary embodiment, a needle magnetizing arrangement according to the present invention comprises a controller adapted to generate a first magnetic field for magnetizing a needle, and a magnetic field sensor adapted to generate a signal based on a second magnetic field of the needle. 
     In an exemplary embodiment, the needle magnetizing arrangement further comprises a coil coupled to the controller. The controller passes current through the coil. 
     In an exemplary embodiment, the needle magnetizing arrangement further comprises a magnetic guide adapted to guide a flux of the second magnetic field toward the magnetic field sensor. The magnetic guide is coupled to the magnetic field sensor. 
     In an exemplary embodiment, the needle is coupled to a removably needle assembly or a syringe. 
     In an exemplary embodiment, the needle magnetizing arrangement further comprises a magnetic shield at least partially enclosing an area around the needle. The magnetic shield circumferentially encloses the area around the needle. The magnetic guide is enclosed by the magnetic shield. The magnetic shield is composed of Mu-metal, permalloy or electrical steel. 
     In an exemplary embodiment, the needle magnetizing arrangement further comprises a processor electrically coupled to the magnetic field sensor and adapted to receive the signal. The processor executes a predetermined action when the signal indicates a presence of the second magnetic field. The predetermined action is providing an audible or visual feedback. 
     In an exemplary embodiment, the arrangement is integrally formed with or removably coupled to an injection device. The predetermined action is preventing use of the injection device. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein: 
         FIG. 1  is a schematic view of an exemplary embodiment of a needle magnetizing arrangement according to the present invention, 
         FIG. 2  is a schematic top cross sectional view of an exemplary embodiment of a needle magnetizing arrangement according to the present invention, 
         FIG. 3  is a schematic view of an exemplary embodiment of a needle magnetizing arrangement according to the present invention before use, 
         FIG. 4  is a schematic view of an exemplary embodiment of a needle magnetizing arrangement according to the present invention during use, and 
         FIG. 5  is a schematic view of an exemplary embodiment of a needle magnetizing arrangement according to the present invention after use. 
     
    
    
     Corresponding parts are marked with the same reference symbols in all figures. 
     DETAILED DESCRIPTION 
       FIG. 1  is a schematic view of an exemplary embodiment of a needle magnetizing arrangement  1  according to the present invention. In an exemplary embodiment, the arrangement  1  is used to magnetize a needle  2  which is attached to a removable needle assembly  8 . For example, the needle  2  may be a double-tipped needle in the needle assembly  8  which can be removably engaged (e.g., threaded) to a medicament delivery device and/or a medicament cartridge. In another exemplary embodiment, the needle  2  may be coupled to a syringe. Those of skill in the art will understand that the needle  2  may be coupled to any transcutaneous device. 
     In an exemplary embodiment, the needle magnetizing arrangement  1  comprises a controller  4  having a coil  3 . When activated, the controller  4  passes a current through the coil  3  to generate a magnetic field for magnetizing the needle  2 . Magnetizing the needle  2  may create magnetic poles  2 . 1 ,  2 . 2  on the needle  2 , which exhibit a magnetic field F. 
     In an exemplary embodiment, the needle magnetizing arrangement  1  includes a magnetic field sensor  5  for determining a magnetic field strength of the needle  2  before and after the magnetization. A magnetic guide  6  disposed adjacent the sensor  5  may comprise a magnetically soft material for guiding a magnetic flux of the needle  2  to the magnetic field sensor  5 . The guide  6  may thus focus and/or amplify the magnetic field strength detectable by the magnetic field sensor  5 . A magnetic shield  7  may be arranged around the magnetic field sensor  5  and the needle  2  for limiting impact of ambient magnetic fields on the magnetic field sensor  5 . For example, the magnetic shield  7  may enclose an area around the needle  2  and facilitate measurement of low magnetic field strengths. 
     In an exemplary embodiment, the sensor  5  may generate an electrical signal that is utilized by a processor  10  for taking a predetermined action. For example, if the signal indicates the needle  2  has been previously magnetized, the processor  10  may prevent an injection procedure from occurring, may provide a feedback to a user, etc. When a new, magnetically neutral needle is detected, the processor may allow an injection procedure, may provide a feedback to a user, etc. 
     In an exemplary embodiment, the arrangement  1  may be integrally formed with an medical device or may be removably coupled thereto. For example, the arrangement  1  may be utilized with a plurality of different medical devices which utilize needles or components having needles. 
       FIG. 2  is a schematic top cross sectional view of an exemplary embodiment of the needle  2 , the magnetic shield  7  and the magnetic guide  6 . In the exemplary embodiment, the shield  7  circumferentially encloses the needle  2  and the guide  6 . This configuration may limit noise (e.g., due to ambient magnetic fields) in the signal generated by the sensor  5 . In other exemplary embodiments, the shield  7  may partially enclose the needle  2 . In another exemplary embodiment, the guide  6  may be embedded wholly or partially in the shield  7 . 
       FIG. 3  is a schematic view of an exemplary embodiment of the needle magnetizing arrangement  1  prior to use. Prior to use, the needle  2  is magnetically neutral. 
       FIG. 4  is a schematic view of an exemplary embodiment of the needle magnetizing arrangement  1  during use. The magnetization controller  4  passes a current I through the coil  3  thereby generating a magnetic field F. In an exemplary embodiment, the magnetization controller  4  may generate the current I by discharging a capacitor  9 . As the needle  2  is exposed to the magnetic field F, the needle  2  is magnetized, thus providing a magnetic orientation with a north pole  2 . 1  and a south pole  2 . 2 . This magnetic orientation remains even after removing the magnetic field F by switching off the current I through the coil  3 . Hence, the needle  2  has a permanent (or semi-permanent) magnetic field F R  as illustrated in  FIG. 5 . 
     Those of skill in the art will understand that the current I may passed through the coil  3  in the opposite direction thereby switching the orientation of the magnetic field F and reversing the magnetic orientation of the needle  2 . 
     Preventing re-use of needles may reduce the risk for causing the user pain when inserting a blunt needle and mitigate the risk of cross contamination by used non-sterile needles. 
     In an exemplary embodiment when using a needle  2  with a net magnetization of zero prior to use, the needle magnetizing arrangement  1  may be used to distinguish three different states of the needle  2  by detecting whether the net magnetization is different from zero and whether the north pole  2 . 1  points in a distal direction D or in a proximal direction P. The magnetization controller  4  may be arranged to accordingly magnetize the needle  2 . In order to detect a direction of the magnetic field F R  the magnetic field sensor  5  may for example be arranged as an XMR sensor using one of the magneto resistant quantum effects GMR (giant magneto resistance), AMR (anisotrope magneto resistance), CMR (colossal magnetor resistance), or TMR (tunnel magnetor resistance). If the direction of the magnetic field F R  is irrelevant the magnetic field sensor  5  may also be a Hall sensor. 
     In another exemplary embodiment the magnetization controller  4  may be arranged to de-magnetize a magnetized needle  2  by driving an alternating current through the coil  3 . In this case an unused needle  2  could have an initial net magnetization different from zero while a used needle would be marked by de-magnetizing it. 
     Those of skill in the art will understand that modifications (additions and/or removals) of various components of the apparatuses, methods and/or systems and embodiments described herein may be made without departing from the full scope and spirit of the present invention, which encompass such modifications and any and all equivalents thereof.
A needle magnetizing arrangement ( 1) comprising a controller ( 4) adapted to generate a first magnetic field (F) for magnetizing a needle ( 2), and a magnetic field sensor ( 5) adapted to generate a signal based on a second magnetic field (F R) of the needle ( 2).