Patent Publication Number: US-2021187206-A1

Title: Syringe destruction

Description:
This invention relates to an apparatus and method for the safe destruction of used syringes. 
     Syringes are used ubiquitously in medicine and other applications, and generally comprise a syringe main body and a hypodermic needle affixed to the syringe main body. The syringe main body typically comprises a cylinder and a plunger, whicn acts as a piston to force and/or draw fluids through an opening at the end of the cylinder. The opening is typically formed as a spigot, to which the hypodermic needle is sealingly affixed. Meanwhile, the hypodermic needle comprises a hub, which connects to the syringe&#39;s spigot, and a tubular needle with a sharp tip, which protrudes therefrom. The hub can be connected to the spigot by frictional engagement, via a screw-threaded connection, a bayonet-type connection, etc. 
     The syringe can be used for injecting or withdrawing liquid substances into, or from, a patient&#39;s circulatory system in a manner that is well understood. The needle for a hypodermic syringe typically comprises a fine metal tube with a sharp end, which is adapted, in use, to pierce the patient&#39;s skin and, in many cases, enter a blood vessel for the delivery of a liquid medicament, or the extraction of a fluid, as the case may be. Once used, a hypodermic needle needs to be disposed of safely because the needle becomes contaminated during use. If a medical practitioner inadvertently suffers a “needle stick injury”, i.e. if he/she pierces their own skin with a contaminated needle, then there is a risk of disease/infection being passed from the patient to the medical practitioner. 
     Various methods of disposing of hypodermic needles are known, for example, the use of “sharps bins” into which used/contaminated needles are placed. A sharps bin generally comprises a pierce-resistant main body, which prevents, or inhibits, the contaminated needle points from coming into contact with people. The sharps bin usually has an obstructed opening that permits needles to be placed into the main body, but which prevents or restricts a user from placing their hand or other body parts into the main body. 
     Other methods of hypodermic needle destruction are disclosed in, for example, published PCT application No. WO2015/011443. In this disclosure, the sharp end of the needle is inserted into a device, whereupon a current is passed through the needle to soften/melt its tip. Axial compression of the needle, whilst in the softened/melted state, causes the needle tip to be deformed into a blunt ball, which prevents the formerly sharp tip from posing a needlestick injury. Moreover, hypodermic needle destruction devices of this general type also have the advantage of heating the needle to or near its melting point, the heat of which destroys any viruses, bacteria and contaminants. Devices of this general type therefore offer two-fold protection, that is: blunting and sterilising the needle. 
     It will be appreciated from the foregong, that devices and methods for the disposal of hypodermic needles are well-known. However, once “destroyed” there still exists a potential problem with waste management because even though the needle has been blunted/sterilised, it is still attached to the syringe. 
     As such, a further problem exists in relation to the waste stream for used syringes because of the materials of manufacture, namely the metal of the needle, the epoxy resin/piastic of the hub, as well as the plastic of the main body of the syringe. When these materials are “co-mingled”, recycling of these various components is extremely difficult—especially where a biohazard is involved as well. 
     The needle and syringe can therefore benefit from being treated/processed via different waste streams (e.g. plastics vs metals vs non-recyclables), and so it is often desirable to disassemble the syringe, that is to say, to separate the blunted/sterilised needle from the syringe so that the two can be disposed of separately. 
     Whilst needle destruction devices, such as that described in published PCT application No. WO2015/011443 are known, there still exists a need to further “process” the syringe by disassembling it, which according to the state of the art, requires a user to manually separate the needle from the syringe. Further, even though devices such as that described in published PCT application No. WO2015/011443 can destroy the needle, there is nevertheless a finite risk of needlestick injury whilst handling the un-treated syringe prior to destruction, and whilst manipulating it into the needle destruction device. 
     A need therefore exists for a solution to one or more of the above problems, which this invention aims to provide. 
     Various aspects of the invention are set forth in the appended independent claim or claims. Optional or preferred features of the invention are set forth in the appended dependent claims. 
     According to an aspect of the invention, there is provided: a syringe processing apparatus for syringe disposal, the syringe comprising a main body and a hypodermic needle affixed thereto, the main body comprising a spigot to which a hub that supports a needle part of the hypodermic needle is affixed, the syringe processing apparatus comprising: a needle destruction assembly for destroying the needle part of the hypodermic needle, the needle destruction assembly comprising a conductive clamping electrode adapted to clamp the needle part of the hypodermic needle at a point between the hub and its tip, a conductive tip electrode for contacting the tip of the needle part of the hypodermic needle, the tip electrode being driven to move coaxially with an axis of the needle part of the hypodermic needle, means for applying a voltage between the clamplng electrode and the tip electrode as the tip electrode is advanced towards the hub, such that resistive heating of the needle occurs in conjunction with axial compression exerted by the tip electrode on the needle, which softens/melts the tip of the needle, thereby blunting and sterilising the needle tip, the apparatus further comprising: a cradle for supporting and holding the main body and being driven to move the main body along a locus that is parallel with the said axis; and a hub grip assembly for gripping the hub of the hypodermic needle, which comprises an annular grip part adapted to engage the hub of the hypodermic needle when the cradle is driven along the said axis, wherein the cradle and hub grip assembly are relatively moveable so as to separate the hub of the hypodermic needle from the spigot of the mam body. 
     By making the cradle and hub grip assembly relatively moveable, it is possible to automate the disassembly of the hypodermic needle from the syringe. In certain embodiments, a controller is provided that coordinates the relative movement so as to overcome frictional engagement between the hypodermic needle and the spigot of the syringe and/or to unscrew the hypodermic needle from the spigot of the syringe; and/or disconnect a bayonet-type connection between the hypodermic needle and the spigot of the syringe. 
     Suitably, the needle destruction assembly further comprises a containment cylinder, which surrounds the needle part of the hypodermic needle, and within which the tip electrode is arranged to move. The containment cylinder suitably prevents or inhibits the needle part of the hypodermic needle from bowing or buckling as the axial compressive force is applied thereto. 
     The containment cylinder may additionally comprise a heater coil, for pre-heating the containment cylinder or a needle located therein. This can be useful for driving-off moisture or liquids within the containment cylinder and/or within the bore of the needle part of the hypodermic needle prior to the application of the voltage and axial compression. If moisture is present during the heating compression process, vapour droplets can form, which can adversely affect the formation of a blunt ball of metal at the needle tip. 
     In certain embodiments of the invention, there is provided an induction coil surrounding the needle, which carries an electric current that incuces, in use, a current in the needle. Resultant eddy current heating of the needle can be used to assist the melting process via resistive/Ohmic heating. 
     The voltage applied between the tip electrode and the clamping electrode can be of any suitable type, such as a DC voltage, an AC voltage, and RF voltage or any other suitable voltage. A control/feedback system is suitably provided for coordinating the application of the voltage and the axial compression force. As the needle tip melts, it will tend to recede from the tip electrode, thereby either breaking the circuit and/or by increasing the resistance in the circuit. As such, a high speed feedback circuit ts suitably provided, which controls the applied voltage end displacement of the tip electrode so as to maintain the tip electrode in contact with the tip, whilst maintaining the current within the needle (between the clamping and tip electrodes) within specified parameters. 
     The tip electrode suitably comprises a formation, such as a recess, for centralising the tip of the needle part of the hypodermic needle with the centre of the tip electrode. 
     The tip electrode is driven to move coaxially with an axis of the needle part of the hypodermic needle and this can be by way of a pulley belt arrangement, a rack and pinion, a worm screw, a linear actuator, or by any suitable means. 
     The cradle supports and holds the main body of the syringe and is driven to move the main body along a locus that is parallel with the said axis. Movement of the cradle can be by way of any suitabie means, such as a pulley belt arrangement, a rack and pinion, a worm screw, and/or a linear actuator. 
     In one embodiment, the cradle comprises a main body, which is shaped to receive the syringe main body. The shape suitably comprises end abutments, which engage the distal and proximal ends of the syringe main body, thereby preventing or inhibiting axial displacement of the syringe relative to the cradle. 
     In certain applications, the hypodermic needle is not coaxial with the centreline of the syringe main body, and this can make it difficult to maintain the required axial alignment of the various parts of the syringe processing apparatus. In certain embodiments, therefore, means is provided for adjusting the cradle configuration such that the hypodermic needle automatically aligns with a datum line, which datum line can be brought into alignment with the axis of the syringe processing apparatus. 
     In one embodiment, a centraliser is provided, which comprises a tapered aperture that “catches” the hypodermic needle as a syringe is placed into the syringe processing apparatus. The taper is suitably configured to cause the needle part of the hypodermic needle to align with an axis of the centraliser, and be retained thereby, for example, by gravity. With the needle part of the hypodermic needle (with the syringe attached thereto) temporarily retained by the centraliser, adjustable grip means of the cradle can be used to grip the syringe main body before the configuration is effectively locked-in. Now, the centraliser can be removed, and the alignment of the needle part of the hypodermic needle is fixed relative to a datum of the cradle, which conveniently aligns with the axis of the syringe processing apparatus, and so now the apparatus is correctly set-up and aligned. 
     The hub grip assembly grips the hub of the hypodermic needle by way of an annular grip part adapted to engage the hub of the hypodermic needle when the cradle is driven along the said axis. The annular grip part suitably comprises a resiliently deformable annulus, for example, manufactured from an elastomeric material, which frictionaily engages the hub as it is axially inserted into it. 
     The cradle and hub grip assembly are relatively moveable so as to separate the hub of the hypodermic needle from the spigot of the mam body. This can be by way of axial displacement of the cradle relative to the hub grip. This configuration may be used to disconnect a frictionally-engaged hub from the syringe&#39;s spigot. In this case, the frictional engagement of the hub with the hub grip should be greater than the frictional engagement of the hub with the syringe&#39;s spigot. 
     However, in certain embodiments, the hub grip can be configured to rotate about the said axis, for example, by driving the annual hub grip using a ring gear driven by an electric motor. By such means, the hub can be rotated (about the said axis) relative to the spigot of the syringe. Rotating/oscillating the hub relative to the spigot can often be sufficient to separate it from the spigot. 
     In certain embodiments, the rotation/oscillation of the hub relative to the spigot is coordinated with axial displacement of the hub relative to the spigot. A controller may be used for this purpose, which measures and/or controls the forces and/or displacements that occur. It will be appreciated that the coordinated use of relative rotational and relative axial displacement can be used to unscrew a screw-threaded hub from the spigot and/or to disconnect a bayonet connected hub from the spigot. 
     The control system could comprise a logic circuit, which attempts to disconnect the hub from the spigot via various methods, such as: axial displacement (friction-fitted hub); axial displacement+rotational oscillation (tightly friction-fitted hub); axial displacement+rotation (screw-fitted hub); axial rotation+linear displacement (bayonet-connected hub). By measuring the forces and displacements, the control system could be configured to assess whether each method has worked, before proceeding to another method if not. 
    
    
     
       Syringe destruction devices in accordance with the invention are shown in the accompanying drawings in which: 
         FIG. 1  is a schematic side view of a first embodiment of an apparatus in accordance with the invention; 
         FIGS. 2, 3, 4, 5, 6, 7, 9 and 10  are a sequence showing the operation of the apparatus shown in  FIG. 1 ; 
         FIG. 8  is a partial perspective view of a feature shown in  FIG. 7 ; 
         FIG. 11  shows an alternative embodiment of the invention comprising a centraliser; and 
         FIGS. 12-14  are a sequence showing the operation of the apparatus shown in  FIG. 11 . 
     
    
    
     A syringe disposal device  10  in accordance with the invention comprises a cradle  12  adapted to receive, and retain, a syringe  14 . The syringe  14  has a main body  16  and an internal plunger  18 , and the main body  16  has a spigot  20 , to which the hub  22  of a hypodermic needle  24  is fixed. The hypodermic needle  24  also comprises a needle part  26 , which is attached to the hub  22  using a grout or an adhesive. 
     The apparatus  10  has an opening (not shown) through which the syringe  14  can be placed, where it drops  28  down into the cradle  12 . The cradle  12  has a rear abutment  30 , which engages a flange  32  of the main body  16  of the syringe  14 ; a front abutment  34 , which engages the front face  36  of the syringe main body  16 . 
     Once inserted, as shown in  FIG. 2 , the syringe  34  sits in, and is retained by, the cradle  12 . The cradle  12  is mounted on a linear actuator  40 , which in the illustrated embodiment, comprises a rack  42  and pinion  44  arrangement, although other types of linear actuator  44  are within scope of the invention, for example, a pulley system and/or a worm screw. Regardless, the linear actuator  40  allows the cradle  12 , and hence the syringe  14  to be advanced, to the position as shown in  FIG. 3  of the drawings. 
     Referring back to  FIG. 1  of the drawings, the apparatus  10  comprises a hub engagement part  50 , which has an annulus  52 , with a tapered through-hole  54 , frictionally-engages the hub  22  when inserted therein, as shown in  FIG. 3 . The rubber anulus  52  is contained within an annular ring gear  54 , which meshes with a pinion gear  56 , driven by a motor  58 . The operation of the hub-gripping part  50  is described in greater detail below. 
     The apparatus  10  also comprises a set of clamping electrodes  60 , which are made of metal, and which can be separated, as shown in  FIG. 1  to enable the needle  26  to pass therebetween; or moved towards one another, as shown in  FIGS. 4 and 5  of the drawings, so as to clamp the needle  26  therebetween and form an electrical contact therewith. 
     The apparatus  10  also comprises a tip electrode  62 , which is also made of metal, and which has a dish-shaped end  64 , which serves to centralise the tip electrode  62  on the needle  26  tip, in use. 
     The tip electrode  62  is also mounted on a linear actuator  26  which in the illustrated embodiment, comprises a rack  68  and a pinion  70  arrangement, although other linear actuators may equally be used, such as pulley belt system and/or a worm screw. 
     Referring back to  FIG. 3  of the drawings now, the cradle  12  has been advanced such that the hub  22  is fictionally engaged in the rubber anulus  52  and the needle  26  protrudes to a containment cylinder  72  with the tip electrode  62  in a retracted position. An induction and/or heater coil  73  surrounds the containment cylinder  72 . 
     Referring now to  FIG. 4  of the drawings, the clamping electrodes  60  have been moved together so as to clamp the needle  24  therebetween. A voltage  74  is then applied between the clamping electrodes  60  and the tip electrode  62  such that an electric current passes through the needle  24 . Due to resistive/ohmic heating, the needle  24  softens as it heats, and at the same time, the tip electrode&#39;s linear actuator  66  is driven so as to push the tip electrode, along the axis of the needle  24 , towards the hub  22 . 
     The end result is shown in  FIG. 5  of the drawings where the tip electrode  62  has been fully advanced and the needle  24  tip has been blunted and melted into a round ball  74 . The process of heating/melting the needle tip  74  serves to sterilise it as the temperature involved is above that at which bacteria, viruses and other pathogens can survive; whilst at the same time blunting the tip, and thereby removing any risk of a “needle stick” injury. 
     Once the needle  24  has been blunted and sterilised, as shown in  FIG. 6 , the voltage  74  can be removed, the clamping electrodes  60  moved apart and the tip electrode  62  retracted, if necessary. At this point, the hub  22  is still gripped by the anulus  52 . 
     Referring to  FIGS. 7 and 8  of the drawings, it can be seen that the hub grip assembly  50  is now manipulated, by driving the motor  58 , so as to turn the pinion gear  56  and thus the ring gear  54 , which thereby rotates the hub about an axis  76 , which is co-axial with the longitudinal axis of the needle  24 . At the same time, the cradle&#39;s linear actuator  40  is driven so as to slowly retract the cradle  12 , and hence the main body  16  of the syringe  14  such that the rotation of the hub  22  relative to the fixed orientation of the syringe  24  unscrews or releases the hub  22 , and hence the needle  24  from the main body  16 . 
     The result is shown in  FIG. 9  of the drawings, where it can be seen that the syringe body  16  has been fully-separated from the hub  22  of the hypodermic needle  24 . In order to disengage the hub  22  from the anulus  52 , the tip electrode  62  can be advanced again, using its drive mechanism  66 , so as to axially displace the hub  22  from the rubber anulus  52 , thereby releasing it. Referring to  FIG. 10 , a needle waste receptacle  80  is provided to catch the hypodermic needle  24 , after processing, as it falls away from the hub grip assembly  52 . Also shown in  FIG. 10 , is the cradle  12  being inverted so that the remainder of the syringe  14  can fall away  84  into a further waste receptacle  86 . 
     It will be appreciated from the foregoing description that the syringe/needle  14 / 24  can be safely destroyed and disassembled and its parts separated into separate waste streams,  80 ,  86 . Due to the provision or a cradle, it is not necessary for an operator to hold the syringe  24 /needle  24  once it has been used: It can simply be dropped into the apparatus  10 , where the destruction process proceeds automatically, without further user intervention. 
     A further embodiment  100  of the syringe processing apparatus in accordance with the invention comprises an outer housing  102  with an aperture  104  through which a syringe can be dropped  6 , in use. Identical reference signs have been used in  FIGS. 11 to 14  to those used in  FIGS. 1 to 8 , to identify identical features and thus avoid unnecessary repetition herein. 
     The main difference between the embodiment  100  shown in  FIGS. 11-14  of the drawings, and that shown in  FIGS. 1-10  of the drawings, is the addition of a “self centralising” cradle  110 . The self-centralising cradle  110  comprises a main cradle part  112 , which carries a pair of adjustable grips  114 , which are driven to move by actuators  116 , in this case, rack  118  and pinion  120  devices. The adjustable grips  114  are mounted on a plate  122  which has a slotted aperture  124 , which permits the plate  122  to move left/right (as shown in the drawing). A mount  126  locates within the slotted aperture  124  and allows the plate  122  to move left/right (as shown in the drawing) as previously described, and a locking ring  128  enables the position of the plate  122  relative to its mount  126  to be locked. 
     As shown in  FIG. 12  of the drawings, when a syringe  14  is dropped into the device  100  via the aperture  104 , the needle  24  is guided by the tapered centraliser parts  132  such that the needle  24  falls into the space  136  between the centraliser parts  132 . This aligns the needle with the axis of the tip electrode  64 . Once in this position, the adjustable grip parts  114  can be driven  142  towards the syringe  14  such that they engage with the sides of the main body  16  of the syringe  14 . 
     It will be appreciated that the right-hand grip part  114  (as shown in the drawing) will contact the main body  16  and the syringe  14  first (in this example), at which point the plate  122  will slide  150  right, as indicated by the arrow  150  in  FIG. 12 . Eventually, the second grip part  114  will engage the opposite side of the syringe  14  main body  16  and the syringe  14  will be clamped between the grip parts  114 . At this point, the locking ring  128  can be tightened to lock plate  122  relative to its mount  126  and now the plate  122  can be moved  152  axially with the needle  24  centralised on the axis  140  of the device  100 . 
     This configuration is shown in  FIG. 13 , whereby the grip parts  114  have engaged the main body  16  of the syringe  14  and the plate  122  has moved  150  so that the needle  24  is aligned with the axis  140 . 
     Referring now to  FIG. 14  of the drawings, the centraliser parts  132  have been moved apart and this enables the plate  122  to be driven  154  downwards (in the drawings), for example using a rack  42  and pinion  44  actuator arrangement  40 . The plate  122  can be driven down  154  until the hub  22  engages the annular hub grip  52  in the manner previously described, and the needle destruction procedure and needle/syringe separation procedure can proceed in the manner previously described with reference to  FIGS. 1 to 10  above. 
     It will be appreciated that the invention is not restricted to the details of the foregoing embodiments, which are merely exemplary of the invention. For example, the linear actuators have been described as being rack and pinion devices, they could equally be pulley belt type arrangements, linear actuators or worm screws.