METHOD AND APPARATUS FOR DESTROYING NEEDLES

Abstract: Biohazardous needles, in one embodiment, are destroyed by the application of an electrical arc that progressively destroys the needle and seals hollow needles. An elongated electrode that slopes up and away from the needle supports is used to strike and then progressively support the destructive arc. In another embodiment, an electrical arc is used to blunt the sharp end of the needle by melting it and allowing it to solidify into a spherical cap.

Description: METHOD AND APPARATUS FOR DESTROYING NEEDLES BACKGROUND OF THE INVENTION This invention relates to the destruction of biohazardous needles and, in particular, to the electrical destruction of used hypodermic needles. Increasing emphasis has been placed on protecting patients and health professionals from needle sticks that may spread such pathogens as hepatitis and HIV. Various disposal containers have been used. Needles with various shielding schemes have been employed. Devices that cut needles have been tried. To destroy the needle itself, devices have been used that melt the needle by connecting the needle across a large current source. Such devices reguire an extreme amount of current because of the relatively low resistance of the needle. This makes portable use impractical and line-powered power supplies expensive. In addition, this destruction mechanism soon destroys the contacts of the device as well as the needles. SUMMARY OF THE INVENTION An apparatus for destroying a biohazardous needle having a proximal portion and a distal tip portion includes: an upper electrode adapted to contact the proximal portion; a lower electrode; and an electric arc supply connectable between the upper and lower electrodes. The supply is adapted to produce an electric arc between the lower electrode and the distal tip portion to destroy the needle. A method for destroying a biohazardous needle having a proximal portion and a distal tip portion includes: providing an electric arc supply having an upper and a lower output contact; connecting the upper output contact to the proximal portion; and creating an arc between the distal tip portion and the lower output contact where the arc progressively destroys the needle. In a modified embodiment of the invention, the electrical arc treatment is essentially limited to the sharp distal end of a needle such as a hypodermic needle, that has been used and is, therefore, potentially biohazardous. In this method, the sharp end of the needle is first transformed into a molten mass globule which is then allowed to solidify almost instantly into an integral, blunt, closed cap on the remainder of the needle. The blunt character of the needle makes it "stick" resistant such that the risk that it will accidentally pierce a person's skin is greatly reduced. Moreover, the fusion of the material into an integral cap prevents discharge of any residual material that might exist in the remainder of the needle or piston chamber of the syringe. This point blunting embodiment simplifies the apparatus over that required to destroy the full length of a needle and to contend with the remnants of the needle material. The apparatus is simplified in large part because it need only receive a known length portion of any needle regardless of the needle's actual full length. With simple componentry and relatively small electrical power requirements to treat a needle tip, the invention can be embodied in a small portable device. Such a device can be carried by a medical professional or assistant making it available where needles are used, ideally, right at a patient's side. This allows needles to be blunted immediately or shortly after use with relative ease. Consequently, the danger of accidental needle sticks is greatly minimized since the number of times a needle must be handled before it is blunted is reduced and the number of people potentially handling or otherwise exposed to a needle before it is blunted is reduced. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a needle destroying apparatus according to the invention; FIG. 2 is a perspective view with portions cut away of an apparatus according to the invention; FIG. 3 is a fragmentary cross-sectional view of a needle blunting apparatus according to a second embodiment of the invention receiving a sharp needle end; FIG. 4 is a block diagram of the electrical power system of the second embodiment; FIG. 5 is a cross-sectional view of a base of the apparatus of the second embodiment; and FIG. 6 is a fragmentary cross-sectional view of the apparatus of the second embodiment, similar to FIG. 3, showing a blunted needle end. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a needle destroying apparatus 10 includes an upper electrode 12, a lower electrode 14, an arc power supply 16 and a control 18. The needle 1 may be advantageously immobilized by a shutter effect between a stationary aperture 20 and an aperture 22 in the plate-like electrode 12 when the electrode 12 is moved along the direction A. The electrode 12 may be moved by various mechanisms, including, for example, a manually operated linkage or camming action or such other well-known techniques as an electrically-operated solenoid or motor and gear train or linkage. The upper electrode may be, for example, comprised of stainless steel. It would of course be possible to maintain the electrode 12 stationary and instead move the aperture 20 (i.e., a member containing the aperture 20) The electrode 14 may advantageously be an elongated member lying generally in a plane through the needle 1. The lower portion of the electrode 14 is located closer to the tip or distal portion of the needle 1 than is the upper portion of the electrode 14 with respect to the upper or proximal portion of the needle 1. In the preferred embodiment, the electrode 14 is a straight rod of a heat-resistant electrical conductor. The electrode may be, for example, stainless steel, or for higher heat resistance, tungsten. The electrode 14 may be, for example, a circular rod as long or longer than the needle to be destroyed and between 0.020 and 0.060 inches in diameter, with 0.032 inches preferred. The electrode 14 may be mounted on a carrier more fully described below. The electrode 14 may be moved along the direction B by various mechanisms, including, for example, a manually operated linkage or camming action or such other well-known techniques as an electrically-operated solenoid or motor and gear train or linkage. As more fully described below, movement of the electrode along the direction B facilitates the striking of an electric arc between the electrode 14 and the needle 1, as well as the removal of "ash" from the end of the needle 1. The arc power supply 16 provides high voltage between the electrodes 12, 14 sufficient to establish an air arc between the needle 1 and the electrode 14 while the proximal portion of the needle 1 is in electrical contact with the electrode 12. The arc supply 16 provides sufficient current in combination with the voltage to destroy the needle 1 using the heat of the arc to a point close to the electrode 12. The arc supply 16 may include, for example, a battery or line powered oscillator driving a step-up transformer. The output of the arc supply may be, for example, about 25 milliamps at 800 volts for needles in the range of 27-32 gauge. Larger needles of 18-26 gauge may require about 125 milliamps at 800 volts. In general, a maximum arc distance of about one-quarter inch has been satisfactory. In the preferred embodiment, the arc supply 16 includes a full-wave rectifier that provides direct curient to the electrodes 12 , 14 with the electrode 12 having a negative polarity with respect to the electrode 14. The control 18 controls the operation of the apparatus 10. The control 18 may be, for example, simply a manual switch to control power to the arc supply 16 or it may be a more complex device as described more fully below. In operation, the needle 1 of a syringe or other biohazardous needle is inserted into the aperture 20. The electrode 12 is moved to contact the needle 1 trapping it between the walls of the aperture 20 and the aperture 22. The arc supply 18 is energized and the electrode 14 moved against the distal tip of the needle 1, temporarily shorting the arc supply 18, and the electrode 14 is then pulled away from the needle 1 thereby striking an arc between the needle 1 and the electrode 14. The resulting arc melts/burns the tip of the needle 1 and the arc continues up the portion of the electrode 14 closest to the remaining lower portion of the needle 1, progressively destroying the needle as the arc travels upward. After the needle 1 is destroyed by the arc, the electrode 12 is released and the stub of the needle 1 withdrawn from the apertures 20, 22. The increasing distance between the electrode 14 and the needle 1 towards the upper proximal portion of the needle 1 helps ensure that the arc starts at the distal tip of the needle 1 and moves toward the proximal portion. This is due to a combination of air heated by the arc tending to push the arc upward balanced by the tendency for the arc to jump to the closest point between the electrode 14 and the needle 1. The needle/electrode are not required to be in a vertical plane but the proximal portion of the needle 1 should be higher than the distal tip. The angle between the needle 1 and the electrode 14 may be, for example, between 10 and 15 degrees with 12 degrees being satisfactory. In the case of hollow hypodermic needles, the apparatus 10 has the further advantage that the progressive melting of the needle 1 results in a melted bead of metal that both blunts and seals any remaining portion of the needle 1. By maintaining the electrode 12 negative with respect to the electrode 14, it has been found that the majority of the heat from the arc is transferred to the needle 1 instead of to the electrode 14, greatly improving the durability of the electrode 14. It has been found that the use of an air arc to destroy the needle, as opposed to destroying it with a short circuit, requires much less power and greatly improves the durability of the contact electrodes. The lower power required makes it possible to operate the device for small gauge needles such as insulin syringes on a few AA batteries for hundreds of needles. In this low power configuration, it is desirable to move the electrodes 12, 14 with a manually operated linkage that also operates a switch for the control 18. Referring to FIG. 2 a solenoid-based embodiment of the invention includes a carriage 24 carrying the electrode 14 at the bottom of a v-shaped groove. The carriage 24 may be, for example, an electrically insulating plastic or, for higher heat resistance, a ceramic material. The carriage 24 is mounted on the plunger of a solenoid 26 and the electrode 12 is mounted to the plunger of a solenoid 28. A light emitting diode 30 and a phototransistor 32 are mounted about the needle 1. In this case, the control 18 uses the diode 30 and the transistor 32 to detect the presence of a needle 1. The control 18 energizes the solenoid 28 to move the electrode 12 to contact and grasp the needle 1. The control 18 also energizes the solenoid 26 to bring the electrode 14 into momentary contact with the needle 1 to strike the arc. When operating with larger gauge needles, ash may be left in place of portions of the needle 1 resulting in interference with the progression of the arc. The solenoid 26 may also be energized by the control 18 to use the carriage 24 to periodically knock this ash loose. For longer needle lengths, the electrode 14 can be advantageously increased in length also. This results in an electrode having an upper portion that would be much farther away from the needle 1 when the lower portion of the needle was in contact with or close to the distal tip of the long needle. This would then require a much higher voltage to sustain the arc at the proximal portion of the needle 1. This would in turn negatively impact the required power, the dissipated heat and the required electrical insulation and electronic component working voltages. As an alternative, the electrode 14 can be initially positioned in an intermediate position suitable for shorter needles. Then a longer needle can be sensed by the control 18 when the distal tip of the needle contacts the electrode 14 prior to the electrode 14 being moved to strike an arc. The control 18 can then energize the solenoid 26 (or another unshown solenoid) to move the electrode 14 further away to accommodate the longer needle. If the arc to the proximal portion of the longer needle extinguishes because of the further distance, the control 18 can energize the solenoid 26 to move back to the intermediate position and to then strike a new arc. Additional increments of movement by the electrode 14 can of course be employed to accommodate even a wider range of needle lengths. The control 18 may include, for example, discrete logic or a microprocessor to perform the required control functions. The present invention may be readily extended to neutralize not only biohazardous needles but also sharps in general such as sharp-edged surgical instruments like scalpels. Because of the large mass involved, the goal is to dull the cutting edge with an electrical arc rather than trying to destroy the whole blade. In this case, rather than using an elongated electrode that roughly corresponds to the straight needle, a more localized (e.g., a point source) electrode is mechanically moved not just in one direction, but in two, to follow the contour of the cutting edge. Various edge tracking techniques can be used, but the preferred embodiment employs measuring the arc resistance to provide a measure of the distance between the electrode and the cutting edge. This measurement is then used to control servos that position the electrode. This device can of course also be used to destroy needles. Referring now to FIG. 3, apparatus 40 for blunting a distal sharp end 41 of a hollow needle 42 of a hypodermic syringe 43 includes a path 44 for receiving the distal end and a portion of the needle rearward of the end. The path 44, in the illustrated arrangement, is generally vertical and is formed by generally vertical wall areas of a cylindrical bore 46 in a body 47. The body 47 is made of a rigid high temperature electrically insulating material such as ceramic material. The path 44 can take the illustrated form of the cylindrical walls of the bore 46 or can have other forms that, like the bore 46, are capable of guiding the lead or sharp end 41 of the needle 42 to a receiving zone 48. The illustrated receiving zone 48 is formed by a pocket in the body 47 with tapered or conical walls 49 that direct the needle tip or end 41 towards the center or axis of the path 44, which is coincident with the axis of the cylindrical bore 46, as the end 41 is lowered vertically into this zone. A small bore 51 radial to the central axis of the path 44 is formed in the body 47 and receives an electrode 52. The electrode 52 is positioned in the bore 51 with its end 53 recessed slightly from an edge 54 where the bore 51 intersects with the wall 49 of the receiving zone 48. A terminal blade, screw or other suitable element (not shown) permits an electrical circuit discussed below to be connected to the electrode 52. A relatively flat bottom 56 of the receiving zone 48 arrests axial or longitudinal motion of the needle 42 into the receiving zone. Associated with the path 44 is an electrode 57 comprising a pair of opposed electrical conductors 58 in the form of flat blade metal springs. The electrode springs 58 have arcuate configurations that are normally configured to contact or nearly contact one another from opposite sides of the path 44. As shown, the electrode springs 57 in both axial directions along the path 44 extend away from the longitudinal center of the path 44 formed by the axis of the cylindrical bore 46. The electrode springs 58 are each provided with a terminal blade or other suitable element (not shown) for connecting it to the electrical circuit discussed below. FIG. 4 illustrates an electrical power system 60 for developing a destructive needle consuming arc. The power system 60 includes a power source 61, a control circuit 62 and a voltage step-up circuit 63. The power source 61, in the preferred embodiment, comprises a DC battery which can be of a conventional dry cell type or a conventional rechargeable type. The control circuit 62 in its simplest form can be a manually operated switch. The step-up circuit 63, of any suitable type of known electrical circuits, increases the voltage supplied by the power source 61 through the control circuit 62. The voltage can be increased to about 2,000 volts, open circuit, by way of example, where a gap 66 is initially about 1/16 inch with the step-up circuit 63. Depending on the size of the gap 66, other voltages between about 1,000 and 10,000 volts, and even as high as 40,000 volts, open circuit, can be employed. The voltage output of the step-up circuit 63 is connected to the electrodes 52, 57 by high voltage lines 64, 65 with the negative side preferably applied to the spring blade electrode elements 58. FIG. 5 illustrates an optional part 68 of the control circuit 62 that can be used to reduce the risk that the device or apparatus 40 will be used while. being "hand-held" and thereby reduce the risk of accidental needle sticks. This control circuit part 68 includes a set of four electrical switches 69 (two are shown in the plane of FIG. 5) that sense whether or not the apparatus 40 is supported on a flat surface. The switches include fixed contacts 71 and movable spring blade contacts 72. The switches 69 are normally open by virtue of the configuration of the blade 72. Associated with each switch 69 is a foot or button 73 vertically movable in a hole 74 in a housing or base 76 in which other parts of the apparatus 40 are contained. The switches 69 are connected in series with each other and with the ' electrical power source 61. Therefore, unless all four feet 73 are positively moved into the housing 76 to close the switches 69, from the illustrated position in FIG. 5, there is no electrical power delivered to the step-up circuit 63. The weight of the apparatus 40 is sufficient to deflect all of the spring contact blades 72 to close the switches 69 when the apparatus 40 is placed on a flat surface. However, if the apparatus is held directly in a person's hand, all of the feet 73 will not be readily supported from underneath so that the apparatus 40 will not ordinarily operate in such a situation. This feature discourages the practice of using the device while holding it in a person's hand. In operation, a needle is inserted through an opening 77 in the housing 76 and is moved vertically downwardly and longitudinally along the path 44. The sharp distal end 41 of the needle 42 moves through a space between the opposed electrode blades 57 until this end rests against the flat bottom 56 of the receiving zone 48. The control circuit 62 is energized, such as by operation of a manual switch, to apply voltage from the step-up circuit 63 across the electrodes 52, 57. The spring character of the electrode blades 58 establishes and maintains electrical contact with the exterior surface of the needle which is typically an electrically conductive metal. The voltage applied across the electrodes 52, 57 is preferably high enough to enable an arc to jump across the gap between the electrode 52 and the needle tip or end 41. The arc is maintained for a time and power level sufficient to melt the sharp point of the end 41 into a molten mass. The arc extinguishes and the mass agglomerates into a somewhat spherically shaped solid 78 which is thus blunt and serves to weld or cap the hollow needle closed. The result of this action is shown in FIG. 6. By way of example, an arc power of approximately 40 watts can be used to achieve sufficient blunting of a needle 42, requiring about 1/2 second for a typical 27 gauge needle to about 1-1/2 seconds for a typical 18 gauge needle. Particularly where the needle 42 is relatively small, the end of the needle may be melted or otherwise consumed by the arc such that the needle recedes away from the electrode 52 up the length of the needle to a point where the length of the arc by a line of sight from this electrode is greater than that which the voltage can sustain, at which point the arc extinguishes itself. The curved configuration of the blades 58 enable the needle end to be withdrawn regardless of a moderate enlargement of its diameter at the fused solid 78 where it is blunted. Other configurations of the electrode 57 are contemplated. These include a single blade, or a metal roll or rollers. The voltage supplied by the step-up circuit 63 can be regulated so that an initial high voltage can be used to establish an arc and then the current or power delivered can be reduced to obtain the desired results. The disclosed device is somewhat self-regulating because as the agglomerated mass at the lower end of the needle 42 increases in size, the energy it dissipates by radiation and convection approaches the energy coming from the arc. If the mass becomes large enough to reach the wall of the receiving zone 48 or cylindrical bore 46, the material will solidify almost instantly through conduction and melting of the needle will cease. Where a needle is relatively large size, limited feeding of the needle towards the electrode 52 can be performed to ensure that a solid sealed cap is produced. If desired, physical contact between the needle tip and the electrode can be made by a suitable mechanism to strike an initial arc so that a relatively high voltage is not required to start the arc. While the invention has been shown and described with respect to particular embodiments thereof, this is for the purpose of illustration rather than limitation, and other variations and modifications of the specific embodiments herein shown and described will be apparent to those skilled in the art all within the intended spirit and scope of the invention. Accordingly, the patent is not to be limited in scope and effect to the specific embodiments herein shown and described nor in any other way that is inconsistent with the extent to which the progress in the art has been advanced by the invention.

Claims: WHAT IS CLAIMED: 1. An apparatus for destroying a biohazardous needle having a proximal portion and a distal tip portion, said apparatus comprising: an upper electrode adapted to contact said proximal portion; a lower electrode; and an electric arc supply connectable between said upper and lower electrodes, said supply being adapted to produce an electric arc between said lower electrode and said distal tip portion wherein said arc destroys said needle. 2. An apparatus according to claim 1, wherein said arc seals said needle. 3. An apparatus according to claim 1, wherein said electric arc supply is adapted to provide said upper electrode with a negative polarity with respect to said lower electrode. 4. An apparatus according to claim 1, further comprising a lower electrode carriage, said carriage being adapted to move said lower electrode into momentary contact with said needle to strike said arc. 5. An apparatus according to claim 4, wherein said carriage is further adapted to move said lower electrode toward said needle to remove ash therefrom. 6. An apparatus according to claim 4, wherein said carriage is further adapted to move said lower electrode a further distance from said needle if said needle contacts said lower electrode before said lower electrode is moved into momentary contact with said needle. 7. An apparatus according to claim 1, wherein said lower electrode includes an elongate member having a lower portion and an upper portion, said elongate member being adapted to maintain said lower portion closer to said distal tip portion than said upper portion to progressively destroy said needle. 8. A method for destroying a biohazardous needle having a proximal portion and a distal tip portion, said method comprising: providing an electric arc supply having an upper and a lower output contact; connecting said upper output contact to said proximal portion; and creating an arc between said distal tip portion and said lower output contact, said arc progressively destroying said needle. 9. A method according to claim 8, further comprising sealing said needle. 10. A method according to claim 8, wherein said upper output contact has a negative polarity with respect to said lower output contact. 11. A method according to claim 8, further comprising moving said lower output contact into momentary contact with said needle to strike said arc. 12. A method according to claim 8, moving said lower output contact a further distance from said needle if said needle contacts said lower output contact before said lower output contact is moved into momentary contact with said needle. 13. A method according to claim 8, further comprising moving said lower output contact toward said needle to remove ash therefrom. 14. A method according to claim 8, wherein said lower output contact includes an elongate member having a lower portion and an upper portion, said method further comprising maintaining said lower portion closer to said distal tip portion than to said upper portion. 15. An apparatus for neutralizing a biohazardous sharp having a proximal portion and a distal portion, said apparatus comprising: a first electrode adapted to contact said proximal portion; a second electrode; and an electric arc supply connectable between said first and second electrodes, said supply being adapted to produce an electric arc between said second electrode and said distal portion wherein said arc neutralizes said sharp. 16. A method for neutralizing a biohazardous sharp having a proximal portion and a distal portion, said method comprising: providing an electric arc supply having a first and a second output contact; connecting said first output contact to said proximal portion; and creating an arc between said distal portion and said second output contact, said arc neutralizing said sharp. 17. A device for blunting a hypodermic needle comprising a base, a path on the base for receiving the distal end of the needle along a longitudinal direction of the needle, a first electrode adapted to engage the needle when the latter is inserted into the path, a second electrode adjacent the path of the needle, a supply of electrical energy, the supply being electrically connected to the electrodes and being arranged to apply a voltage across the electrodes, the power supply, needle receiving path, and electrode positioning being arranged to establish a destructive arc that melts and agglomerates the distal end of the needle to render it blunt and effectively block its bore. 18. A device as set forth in claim 17, including an electrically insulating material that shields the second electrode from direct contact with the sharp distal end of the needle. 19. A device as set forth in claim 18, wherein said path has a longitudinal direction, said second electrode being laterally displaced from said path. 20. A device as set forth in claim 17, including sensing elements for verifying that the device is supported on a flat surface. 21. A device as set forth in claim 20, wherein said sensing elements are arranged to inhibit actuation of said arc when said sensing elements indicate that said device is not resting on a flat surface. 22. A device as set forth in claim 17, wherein said first electrode is resiliently biased by spring action into said path. 23. A device as set forth in claim 22, wherein said first electrode comprises a pair of opposing electrically conductive elements. 24. A device as set forth in claim 23, wherein said first electrode has surfaces that diverge laterally from a longitudinal direction of the path such that the tip of a needle causes the surfaces to deflect laterally when the tip passes in or out of the path. 25. A method of blunting a biohazardous hypodermic needle or other sharp instrument comprising the steps of contacting the surface of the needle at a location anterior of its sharp end with a first electrode, disposing the sharp end of the needle adjacent a second electrode and establishing an arc between the second electrode and the sharp tip of the needle by a voltage across the electrodes to melt the sharp tip of the needle into an agglomerated mass. 26. A method as set forth in claim 25, wherein the first electrode is arranged at a negative potential relative to the second electrode. 27. A method as set forth in claim 25, wherein voltage across the electrodes is applied at a sufficiently high magnitude to initiate an arc across an air gap between the second electrode and the tip of the needle. 28. A method as set forth in claim 25, wherein the needle is moved longitudinally along a path to where the sharp tip is caused to enter a receiving zone and the second electrode is spaced laterally of said path.

Inventors: ADKINS JOEY B, ADKINS, JOEY, B.
Applicants: ADKINS JOEY B, SAFEGUARD MEDICAL DEVICES INC, ADKINS, JOEY, B., SAFEGUARD MEDICAL DEVICES, INC.
Application year: 2001
Main classification: B23K15
IPC codes: A61M5