GB2528448A

GB2528448A - Method and apparatus for testing dielectric insulation integrity of a device

Info

Publication number: GB2528448A
Application number: GB1412915.9A
Authority: GB
Inventors: William Clive Ross
Original assignee: Zethon Ltd
Current assignee: Zethon Ltd
Priority date: 2014-07-21
Filing date: 2014-07-21
Publication date: 2016-01-27
Also published as: GB201412915D0

Abstract

A method, apparatus 300 and detection circuit 306 for testing the dielectric integrity of an insulated medical instrument 316 such as a diathermy probe, submerged in a conductive solution 320 during test. The circuit supplies a test voltage to the device under test via connector 308, and a representation of the test voltage is compared with a reference or threshold potential to determine whether it is representative of a loading effect, due to a flaw or defect in the insulation integrity significantly lowering resistance and allowing a current to flow to the electrolyte. In embodiments, visual 312, 314 and audible 322 devices alert or notify the operator of a failed or passed test and a wetting agent can be used to ensure maximal surface contact with the insulation coating. In this manner, a uniform test is performed, batch testing is possible and damage caused via sparking is reduced.

Description

Title: METHOD AND APPARATUS FOR TESTING DIELECTRIC INSULATION INTEGRITY OF A

DEVICE

Description

Field of the invention

The field of this invention relates to a method and apparatus for testing the dielectric insulation integrity of one or more device(s), and in particular to a method and apparatus for testing the dielectric insulation integrity of an electro-surgical instrument and/or cable.

Background of the invention

Diathermy is a therapeutic treatment most commonly prescribed for joint conditions such as rheumatoid arthritis and osteoarthritis. Generally, a high frequency electric current is delivered via shortwave, microwave, or ultrasound, in order to generate deep heat in body tissues. The generated heat can be used to increase blood flow, relieve pain, or as a surgical tool to seal off blood vessels or destroy abnormal cells.

In surgical procedures, a diathermy electrode can be applied to a blood vessel, wherein the heat generated in the vessel will cause blood to coagulate and the vessel to be cauterized.

Electro-surgical diathermy instruments are commonly insulated by dip coating with acrylic resins, sleeved polyoletin derivatives or electrostatically sprayed plastic coatings. These materials will deteriorate with use and repeated sterilisation, leading to an array of defects within the insulation.

Severe defects can be identified by longitudinal and radial cracking of the outer surface of the insulation, as well as flaking of the covering at the interface between active and insulated parts.

The integrity of the dielectric (electrical) insulation is profoundly important to prevent inadvertent shock or burns to a patient and/or an operator. Therefore, some manufacturers of diathermy instruments often recommend that high voltage testing should be performed every three uses of the diathermy instrument.

Referring to FIG. 1, a simplified representation of a current limiting topology 100, and a simple representation of a diathermy instrument tester 150 comprising the current limiting topology 100 is illustrated.

The current limiting topology 100 comprises a pulse width modulation (PWM) module 102, operable to control an output voltage contact 104 based on a user defined reference voltage input 106.

A shunt regulator 108 is utilised in order to maintain a steady current within the current limiting topology 100. The shunt regulator 108 continuously adjusts a voltage divider network 110 to maintain a constant output voltage.

A multiplier module 112 up-converts a supply voltage to a DC output voltage of around 3kV, which is output at the output voltage contact 104 and to a feedback contact 114, wherein the feedback contact is fed (not shown) to the PWM module 102 in order to determine a current output.

The output voltage contact 104 is coupled to a brush electrode 152 comprised within the simple representation of the diathermy instrument tester 150, which in this case is a simplified representation of a Buckleys DTU6 diathermy tester. Therein, an output voltage up to around 3.5kV is applied to the brush electrode 152.

A diathermy electrode 154 is operably coupled to the diathermy instrument tester 150, in order to provide a voltage path, via cable 156, back to the current limiting topology 100.

During operation, the diathermy electrode 154 is passed through the brush electrode 152 by a trained operator, thereby (hopefully) ensuring that the trained operator does not make contact with the exposed brush electrode 152.

If the dielectric insulation of the diathermy electrode 154 is intact, a voltage will not be conducted by the diathermy electrode 154 via the cable 156. However, if the dielectric insulation of the diathermy electrode 154 is damaged, voltage will be conducted by the diathermy electrode 154 via the cable 156, causing a short circuit within the diathermy instrument tester 150. In some instances, this short circuit generates an audible alarm and visual illumination of a light emitting diode (LED) in order to inform the operator that the tested diathermy electrode 154 may be faulty.

The inventor of the present application has identified several disadvantages with the prior art diathermy instrument tester 150 and associated current limiting topology 100 illustrated in FIG. 1.

For example, in order for a particular diathermy electrode, for example diathermy electrode 154, to be thoroughly and uniformly tested, an operator is required to pass the whole surface of the diathermy electrode through the brush electrode 152. This can cause the operator difficulty if, for example, the diathermy electrode comprises an irregular shaped complex dielectric layer, which requires multiple passes through the brush electrode 152. In some instances, the brush electrode 152 may not come into contact with the entire surface of the diathermy electrode 154, thereby resulting in one or more test errors that may lead to risks to patients or operators/surgeons of the diathermy electrodes.

Furthermore, the time taken to test the diathermy electrode 154 may take on average around twenty seconds. Therefore, bulk and/or batch testing would take a considerable amount of time.

A knock on effect of the time taken to test a diathermy electrode may also be operator fatigue.

Operators are generally required to test thousands of diathermy electrodes, which is an arduous process and can result in operator error. As a result, faulty diathermy electrodes may be passed as safe to use'. Therefore further levels of quality control may be required to detect operator error.

However, in some instances, some faulty diathermy electrodes may still not be detected, due in part to current sub-standard testing devices.

A further problem with the diathermy instrument tester 150 may be that sparking from the brush electrode 152 can heat and melt an otherwise functional diathermy electrode 154. This may occur if, for example, the voltage is high enough to break down the dielectric coating of the diathermy electrode 154.

In some examples, the sparking may melt dielectric material surrounding a defect within the insulation of the diathermy electrode 154, which may subsequently partially re-seal the insulation around the defect. On a subsequent test, the partially re-sealed defect may not conduct the test voltage from the brush electrode 152, which may lead to a sub optimal diathermy electrode 154 being passed as safe to use.

Therefore, there may be a need to provide a simpler and more effective testing regime, which may allow for uniform testing. Furthermore, there may also be a need to negate or reduce the possibility of human error.

Summary of the invention

In a first aspect of the invention, a medical instrument testing circuit for testing a dielectric integrity of a medical instrument, the medical instrument testing circuit comprising: an output connector arranged to supply a test voltage to a medical instrument at least partially submerged in a solution; and a detection circuit operably coupled to the output connector and arranged to: receive a representation of the test voltage supplied to the medical instrument at least partially submerged in the solution; and determine whether the received representation of the test voltage supplied to the medical instrument at least partially submerged in the solution is representative of a loading effect due to the dielectric integrity of the medical instrument, has been provided. In this manner, a simpler and more effective testing regime, which may allow for uniform testing and negate or reduce the possibility of human error, has been provided.

In an optional example, the detection circuit may be further operable to compare the received representation of the test voltage supplied to the medical instrument at least partially submerged in the solution with a threshold value representative of a loading effect. Advantageously, the detection circuit may be able to determine the dielectric integrity of the medical instrument at least partially submerged in the solution, based on the threshold value.

In an optional example, the medical instrument testing circuit may be further operable to output a first control signal when the test voltage supplied to the medical instrument at least partially submerged in the solution is not representative of the loading effect. Advantageously, the first control signal may be operable to highlight to a user that the dielectric integrity of the medical instrument at least partially submerged in the solution may not be compromised.

In an optional example, the first control signal may be operable to selectively enable a first visual notification device. Advantageously, this example may additionally provide a visual notification to the user.

In an optional example, the detection circuit may be operable to output a second control signal when the test voltage supplied to the medical instrument at least partially submerged in the solution is representative of the loading effect. Advantageously, this may allow the detection circuit to selectively determine whether the dielectric integrity of the medical instrument at least partially submerged in the solution may be compromised.

In an optional example, the second control signal may be operable to selectively enable at least one of: a second visual notification device, an audible notification device. Advantageously, this may visually highlight to the user that the dielectric integrity of the medical instrument at least partially submerged in the solution may be compromised.

In an optional example, the detection circuit may comprise a comparison module operable to compare a reference voltage received from the medical instrument testing circuit with the representation of the test voltage supplied to the medical instrument at least partially submerged in the solution.

Advantageously, the reference voltage may be varied to compensate for different medical instruments.

In an optional example, the detection circuit may comprise a first semiconductor switching device operable to receive the representation of the test voltage supplied to the medical instrument at least partially submerged in the solution and a second semiconductor switching device operably coupled to an output of the first semiconductor switching device.

In an optional example, the first semiconductor switching device may be enabled and the second semiconductor device may be disabled when the representation of the test voltage supplied to the medical instrument at least partially submerged in the solution is not representative of a loading effect.

Advantageously, this may highlight to the user that the dielectric integrity of the medical instrument at least partially submerged in the solution is not compromised.

In an optional example, the first semiconductor switching device may be disabled and the second switching device may be enabled when the representation of the test voltage supplied to the medical instrument at least partially submerged in the solution is representative of the loading effect.

Advantageously, this may highlight to the user that the dielectric integrity of the medical instrument at least partially submerged in the solution is compromised.

In an optional example, the medical instrument may comprise a first conductive layer and a second dielectric layer.

In an optional example, the medical instrument may be an electro-surgical instrument.

In an optional example, the solution may be an electrically conductive solution.

In an optional example, the conductive solution may comprise Fltered water and a welling agent.

In a second aspect of the invention, a medical instrument testing system for testing the dielectric integiity of a medical instrument, the medical instrument testing system comprising: the medical instrument testing circuit of any preceding aspect and/or optional example; and a fluid container operably coupled to the medical instrument testing circuit; wherein, the fluid container is operable to house a solution for receiving the at least partially submerged medical instrument. In this manner, a simpler and more effective testing regime, which may allow for uniform testing and negate or reduce the possibility of human error, has been provided.

In a third aspect of the invention, a method of testing a dielectric integrity of a medical instrument, comprising: supplying a test voltage to a medical instrument at least partially submerged in a solution; detecting a representation of the test voltage supplied to the medical instrument at least partially submerged in the solution; and determining whether the representation of the test voltage supplied to the medical instrument at least partially submerged in the solution is representative of a loading effect due to the dielectric integrity of the medical instrument. In this manner, a simpler and more effective testing regime, which may allow for uniform testing and negate or reduce the possibility of human error, has been provided.

In an optional example, the method may further comprise detecting a reduced representation of the test voltage supplied to the medical instrument at least partially submerged in the solution that is indicative of a fault in the dielectric integrity of the medical instrument. Advantageously, this may allow a fault within the dielectric of the medical instrument at least partially submerged in the solution to be identified.

In an optional example, detecting a reduced representation of the test voltage supplied to the medical instrument at least partially submerged in the solution may be a result of a positive current flowing from the medical instrument at least partially submerged in the solution to the solution.

Advantageously, the solution may contact the entire partially submerged part of the medical instrument and couple any test voltage from the medical instrument at least partially submerged in the solution to the solution.

In an optional example, the positive current flowing from the medical instrument at least partially submerged in the solution to the solution may reduce the received representation of the test voltage supplied to the medical instrument at least partially submerged in the solution. Advantageously, the reduction in the received test voltage may highlight to a user that there may be a defect in the dielectric layer of the medical test instrument at least partially submerged in the solution.

Brief description of the drawings

Further details, aspects and embodiments of the invention will be described, byway of example only, with reference to the drawings. In the drawings, like reference numbers are used to identify like or functionally similar elements. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale.

FIG. 1 illustrates a simplified representation of a diathermy instrument tester and current limiting topology.

FIG. 2 illustrates a block diagram of a simplified dielectric testing circuit 200, according to some examples of the invention.

FIG. 3 illustrates a cross section of a simplified dielectric testing device 300, according to some examples of the invention.

FIG. 4 illustrates a further dielectric testing circuit 400, according to some examples of the invention.

FIG. 5 illustrates a flow chart of an operation of a dielectric testing device, according to some examples of the invention.

Detailed descrirtion Although examples of the invention may be directed to testing diathermy electrodes, this is purely for illustrative purposes, and it is envisaged that some examples of the invention may be applicable to testing any insulated device and/or cable, which may not necessarily be for medical applications.

Further, some examples of the invention may be applicable to any insulated or partially insulated component or tool that is used for high voltage applications, wherein the integrity of the insulation and/or dielectric coating should be maintained for safe operation. Therefore, circuit parameters and device parameters may be scaled to accommodate varying sizes of insulated devices and/or cables to test.

Referring to FIG. 2, a block diagram of a simplified dielectric testing circuit 200 is illustrated, which may be suitable for testing the electrical insulation properties of a fully and/or partially electrically insulated component or tool.

In this example, the simplified dielectric testing circuit 200 may comprise a first power supply module 203, which may be operable to receive an input voltage 201. In some examples, the input voltage 201 may be a 240 volt alternating current (AC) mains supply voltage. Further, the first supply module 203 may be operable to output a direct current (DC) output, which in some examples may be a 12 volt DC output. The output of the first power supply module 203 may be operably coupled to a further supply module 207, which may be a high voltage DC supply module. The first power supply module 203 may output a DC supply voltage 204 to the further supply module 207, which may be operable to receive the DC supply voltage 204 and output up to, say, a 3.5kV DC output voltage to a current limiting module 209. The current limiting module 209 may be operable to receive the up to 3.5kv DC output voltage and piovide a curient limited output to output node 211. In some examples, the current limiting module 209 may provide an output with a microampere current, for example up to 150 microamps.

In some examples, the output voltage at output node 211 may additionally be coupled, via a separate path 213, to a potential divider module 215, for example a resistive divider module. Further, the potential divider module 215 may be operable to reduce the voltage level to a predefined level. An output from the potential divider module 215, which may be a voltage reduced output, may be coupled to a control module 217, which may comprise one or more logic devices.

In this example, the control module 217 may comprise at least one comparison module, which may be operable to compare the output from the potential divider module 215 with a further reference input, which in this example may be derived from the DC supply voltage 204. Therefore, in this example, if there is a change in voltage at output node 211, for example due to a loading condition, the control module 217 may be operable to detect this change in voltage.

In some examples, if the control module 217 detects a change in voltage at output node 211, via for example the potential divider module 215, the control module may output a control signal 1' to indication module 219. If, however, the control module 217 does not detect a change in voltage at output node 211, the control module 217 may output a control signal 0' to indication module 219.

In this example, if the indication module 219 receives a control signal 1' from the control module 217, the indication module 219 may be operable to notify a failed test' to a user. In some examples, a failed test' may be notified to the user via enabling a first visual device and/or an audible device.

In some examples, if the indication module 219 receives a control signal 0' from the control module 217, the indication module 219 may be operable to notify a passed test' to the user. In some examples, a passed test' may be notified to the user via enabling a second visual device and/or a second audible device.

In this example, the indication module 219 may be operably coupled to the DC supply voltage 204 in order to power the indication module 219.

In some examples, the voltage at output node 211 may be operably coupled to an electrically insulated instrument or cable. Further, in the context of the present invention, references to insulated, electrically insulated, and/or dielectrically (or dielectric) insulated are to be considered as interchangeable between one another.

In some examples, the electrically insulated instrument or cable may be an, or part of an, electro-surgical instrument, which may be for example a diathermy, bipolar and/or laparoscopic instrument.

Referring to FIG. 3, a cross section of a simplified dielectric testing device 300 is illustrated, according to some examples of the invention.

In this example, the simplified dielectric testing device 300 may comprise, a casing 302, a fluid container 304, circuitry 306, voltage output connector 308, voltage input connector 310, visual notification modules 312, 314 and audible notification module 322.

In this example, the casing 302 may be manufactured from metal, for example aluminium with a suitable cosmetic coating that can act as a shield to radio frequency radiation, wherein the casing 302 is suitable for accommodating the fluid container 304, which in some examples may be removable. In this example, the fluid container 304 may be manufactured from a conductive metallic sheet material, for example stainless steel.

In some examples, the fluid container 304 may be operably coupled to a high voltage negative supply of the circuitry 306 and earthed via a mains connector. In some examples, the fluid container 304 may be operably coupled to the circuitry 306 via a conductive spring or blade (not shown).

The circuitry 306, which in this example may comprise the simplified dielectric testing circuit 200 of FIG. 2, may be positioned within the casing 302, and be operably coupled to the voltage input connector 310, voltage output connector 308, visual notification modules 312, 314 and audible notification module 322.

In this example, an electrically insulated instrument and/or cable 316 to be tested may be operably coupled via a connector 318 to the voltage output connector 308, and positioned within the fluid container 304. In some examples, the connector 318 may form part of the insulated instrument and/or cable 316.

During a test procedure, the fluid container 304 may be filled, or partially filled, with an electrolyte solution 320, wherein the electrolyte solution 320 may be in direct contact with the entire surface of the electrically insulated instrument and/or cable 316. In some examples, the electrolyte solution 320 may comprise a suitable welling agent, in order to lower the surface tension of the electrolyte solution 320. This may have an advantage of allowing the electrolyte solution 320 to easily encompass substantially the entire surface of the electrically insulated instrument and/or cable 316 instantaneously.

In some examples, in order to determine whether the electrically insulated instrument and/or cable 316 is faulty, the circuitry 306 may be enabled. This may result in a high voltage DC output being operably coupled from the voltage output connector 310 to the electrically insulated instrument and/or cable 316, via connector 318.

In this example, the electrolyte solution 320 is conductive and may be in contact with the entirety of the electrically insulated instrument and/or cable 316. Therefore, if there is a defect within the dielectric material of the insulated instrument and/or cable 316, the high voltage DC output operably coupled to the electrically insulated instrument or cable 316 may cause a positive current flow between the immersed electrically insulated instrument and/or cable 316 and electrolyte solution 320 (coupled via the fluid container 304 to a negative high voltage) located within the fluid container 304, wherein the current flow may cause a loading effect upon an output node, say output node 211 from FIG. 2. Therefore, in some examples, if one or more defects are present within the dielectric material of the insulated instrument and/or cable 316 being tested, this may cause a reduction in the high voltage DC output from the output node 211 via a loading effect.

Subsequently, the voltage across the potential divider module 215 may follow a similar trend to the output node 211, and also reduce. As a result, the control module 217 of FIG. 2 may register a drop in voltage in relation to its (reference) DC supply voltage 204 and, subsequently, output a control signal ito the indication module 219, wherein the indication module 219 may subsequently notify a failed test' by at least illuminating visual notification module 312 and/or audible notification module 322.

In some other examples, where there may be no defects present within the dielectric maternal of the insulated instrument and/or cable 316, the high voltage DC output may not be conducted by the electrolyte solution 320. Therefore, in these examples, there may be no loading effect on the output node 211, which may result in the control circuit 217 not registering a drop in voltage/current at the output node 211. Therefore, the control circuit 217 may output a control signal 0' to the indication module 219, wherein the indication module 219 may subsequently notify a passed test' by at least illumination visual notification module 314.

In some examples, the simplified dielectric testing device 300 may have one or more advantages over the prior art. For example, by immersing an electrically insulated instrument and/or cable 316 to be tested within an electrolyte solution 320, the entire surface of the electrolyte solution 320 may be in contact with the dielectric material of the insulated instrument and/or cable 316. Further, the entire surface of the electrically insulated instrument or cable 316 may be instantaneously in contact with the electrolyte solution 320. Therefore, a user of the simplified dielectric testing device 300 may be able to test the entire surface of the dielectric material of the electrically insulated instrument and/or cable 316 by simply immersing the insulated instrument and/or cable 316 in the electrolyte solution 320, rather than having to methodically and uniformly pass the electrically insulated instrument and/or cable 316 through a brush electrode, such as brush electrode 152 from FIG. 1.

In some examples, a test utilising the dielectric testing device 300 may take only a few seconds, resulting in a much faster and efficient test when compared to known testing systems. Further, some examples of the invention may reduce user error, for example by simplifying the test procedure.

In one example, the voltage input connector 310 may comprise a mains input via an International Electrotechnical Commission (IEC) connector, which in some examples may include a fuse, radio frequency filter, and/or an illuminated on/off switch. Further, visual notification module 314 may comprise a green illumination device, for example a light emitting diode or lamp. Further, visual notification module 312 may comprise an illumination device, for example a red light emitting diode or lamp.

The voltage output connector 308 may comprise twin four millimetre sockets, which may be modified for low insertion and/or extraction force, wherein the output current may be limited to around, say, 150 microamps.

The fluid container 304 may be manufactured from stainless steel, wherein the fluid container 304 in this example may have a nominal capacity of around, say, three litres. In some examples, the fluid container 304 may be operably coupled via a conductive element, for example a conductive spring or blade (not shown), to a negative terminal of the high voltage output node, such as voltage output node 211 of FIG. 2. Further, the fluid container 304 may be earthed via the voltage input connector 310.

In this example, an audible warning sounder 322, for example a piezo electric buzzer, may be mounted within the simplified testing device 300.

Further, in this example, the outer casing 302 may define a cube structure of around, say, 200 millimetres in dimension, and weighing around, say, 2 kilograms.

The voltage input connector 310 may receive an AC input of 240 volts, single phase, with SVA max at 50Hz. The output voltage at the output node may be around 3.5kV at 150 micro amps. Further, the first power supply module may comprise a 12V DC 0.SA AC-DC converter.

In this example, the test voltage source resistance may be around 20 megohms, and a defect conductivity of an electrically insulated instrument and/or cable 316 conducted via the electrolyte solution 320 may have an equivalent resistance of around lOOK ohms to 500K ohms. Therefore, if a defect conductivity is present within the electrolyte solution 320, the high voltage output at output node may be reduced to a much lower level.

In this example, the electrolyte solution 320 may comprise clean filtered tap water. In some other examples, an additional wetting agent may be added to the electrolyte solution 320 to ensure complete and uniform contact between the electrolyte solution 320 and the electrically insulated instrument and/or cable 316.

In some other examples, the electrolyte solution 320 may be any conductive solution.

In some examples, the electrically insulated instrument or cable 316 may be too large to be immersed within the fluid container 304. Therefore, in some examples, the fluid container 304, and therefore the simplified dielectric testing device 300, may be scaled to accommodate an array of different sized insulated instruments and/or cables.

Further, in some other examples, the fluid container 304 may comprise a series of partitioned fluid containers, which may each be isolated from each other. Therefore, in some examples, utilising a number of testing circuits 200, audible notification modules and visual notification modules 312, 314, a plurality of electrically insulated instruments and/or cables 316 may be tested concurrently.

In a further example operation, the electrically insulated instrument or cable 316 may be operably coupled to the voltage output connector 308, and at least partially submerged in the electrolyte solution 320. A DC test voltage may be applied to the electrically insulated instrument and/or cable 316 via connector 318, which in some examples may or may not be part of the electrically insulated instrument and/or cable 316. If the at least partially submerged electrically insulated instrument and/or cable 316 conducts the DC test voltage, i.e. there is a defect within the dielectric layer, the DC test voltage may be coupled to the electrolyte solution 320. This may result in a voltage drop at the output supplying the DC test voltage, which may be due to a positive current flowing from the at least partially submerged electrically insulated instrument and/or cable 316 and the electrolyte solution 320, which may be housed within fluid container 304 operably coupled to a negative supply. In some examples, this positive current flow may reduce the resistivity of the electrically insulated instrument or cable, wherein the reduced resistivity may be between 100k and 500k ohms.

In some examples, a representation of the voltage drop at the output supplying the DC test voltage may be received by the circuitry 306, wherein the circuitry 306 may be operable to enable a first visual and audible notification to a user of the simplified dielectric testing device 300. In some examples, the visual notification device may comprise a red LED and the audible notification device may comprise a buzzer, wherein the visual and audible notification devices may represent a faulty electrically insulated instrument and/or cable.

If, however, there are no detectable defects within the dielectric layer of the at least partially submerged electrically insulated instrument and/or cable 316, there may be no current flow between the at least partially submerged electrically insulated instrument or cable 316 and the electrolyte solution 320. Therefore, in this instance, there may be no reduction in resistivity of the at least partially submerged electrically insulated instrument and/or cable 316, wherein the resistivity may be around megohm. Therefore, in this example, the circuitry 306 may not receive a representation of a voltage drop at the output supplying the DC test voltage and, therefore, a second visual notification device may be enabled instead of the first visual and audible notification devices.

In some examples, the resistivity, current flow, and voltage drop, etc., may be dependent upon one or more of the conductivity of the electrolyte solution, size of defect in the dielectric layer, and/or the volume of the electrolyte solution etc., in contact with the at least partially submerged electrically insulated instrument or cable.

Referring to FIG. 4, a further dielectric testing circuit 400 is illustrated, according to some examples of the invention. In some examples, the further dielectric testing circuit 400 may be incorporated within the simplified dielectric testing device 300 from FIG. 3.

In this example, the dielectric testing circuit 400 may comprise an input voltage module 402, which may be operably coupled to an AC-DC converter 404. In some examples, the input voltage module 402 may output a 240 volt AC supply to the AC-DC converter 404, which may subsequently output, in some examples, a 12 volt DC supply to some other elements within the dielectric testing circuit 400.

In some examples, the AC-DC converter 404 may be operable to output a positive voltage output 405, and a negative voltage output 406.

In this example, the voltage outputs, 405, 406 from the AC-DC converter 404 may be operably coupled to a high output DC voltage supply module 408. Further, one or more decoupling capacitors 410 may be operably coupled between the positive voltage output 405 and the negative voltage output 406, for example to reduce noise within dielectric testing circuit 400.

A positive output 410 of the high output DC voltage supply module 408 may be operably coupled to a dual output node 412 and to an input of a potential divider 414. In this example, the potential divider 414 may comprise a resistive divider network operably coupled to ground 415. An output of the potential divider 414 may be operably coupled to a gate of a first semiconductor switching device 416, wherein a source of the first semiconductor switching device 416 may be operably coupled to ground 415, and a drain of the first semiconductor switching device 416 may be operably coupled to the positive voltage output 405 via, in some examples, a first visual notification device 418. Further, in some examples, the drain of the first semiconductor switching device 416 may be additionally operably coupled to a gate of a second semiconductor switching device 420. A source of the second semiconductor switching device 420 may be operably coupled to ground 415, and a drain of the second semiconductor switching device 420 may also be operably coupled to the positive voltage output 405 via a second visual notification device 422 and/or an audible notification device 424.

In this example, an electrically insulated instrument and/or cable, for example the electrically insulated instrument and/or cable 316 from FIG. 3, may be operably coupled to the dual output node 412, and subsequently positioned within a fluid container, for example fluid container 304 from FIG. 3. In some examples, the electrically insulated instrument and/or cable may be completely immersed within an electrolyte solution, for example electrolyte solution 320 from FIG. 3.

-13 -In some examples, the electrically insulated instrument and/or cable 316 may require one or more insulating protective covers/sleeves to be applied, in order to insulate otherwise deliberately exposed metallic element(s). In some examples, the deliberately exposed metallic element(s) may comprise one or more non-insulated active electrode tips of the electrically insulated instrument and/or cable 316.

In the examples illustrated in FIG. 2, a control module 217, which may comprise at least one comparison module, may be operable to compare a representation of the voltage operably coupled to the electrically insulated instrument and/or cable (say cable 316 from FIG. 3) with a reference voltage.

In the example illustrated in FIG. 4, the control module 217 of FIG. 2 may be replaced by the first semiconductor switching device 416 and the second semiconductor switching device 420, which may be operable to determine whether a received voltage is below a predefined threshold level.

In some examples, the first semiconductor switching device 416 and the second semiconductor switching device 420 may be N-channel enhancement metal oxide semiconductor field effect transistor (MOSFET) devices.

During an example operation, the input voltage module 402 may supply a 240 volt mains supply voltage to the AC-DC converter 404. Subsequently, the AC-DC converter 404 may output around, say, a 12 volt supply to the supply module 408 and to drain connections of the first semiconductor switching device 416 via the first visual notification device 418, and the second semiconductor switching device 420 via the second visual notification device 422 and audible notification device 424.

The supply module 408 may subsequently output a high DC supply voltage, up to around, say, 3.5kV, to the dual output node 412 and the potential divider 41 4.

In some examples, the dual output node 412 may be operably coupled to a suitably electrically insulated instrument and/or cable such as cable 316 from FIG. 3, which may not have any defects within its dielectric layer. Therefore, if immersed within the electrolyte solution, there may not be any substantial current flow between the electrically insulated instrument and/or cable and the electrolyte solution.

In this example, the electrolyte solution may be in direct contact with substantially the entire surface, and/or a significant enough number of molecules, of the immersed electrically insulated instrument and/or cable. In some examples, a wetting agent may be added to the electrolyte solution in order to reduce the surface tension of the utilised electrolyte solution. This may allow the electrolyte solution to spread more easily overthe immersed electrically insulated instrument and/or cable.

Therefore, there may not be a loading effect on the supply module 408, as there may be no current conducted into the electrolyte solution 320. As a result, a constant output and source impedance of the supply voltage 408 of around 20 megohm may be achieved.

A representation of the constant output and source impedance of the supply voltage 408 may be provided to the gate of the first semiconductor switching device 416 by the potential divider 414. In some examples, the representation may be substantially lower than the output voltage supplied to the dual output node 412, which may be due in part to the component values of the potential divider 414.

In this example, the representation of the supply voltage 408 may be sufficient to enable' the first semiconductor switching device. For example, the representation of the supply voltage 408 may be sufficient to provide a required threshold voltage to the gate of the first semiconductor switching device 416, which may enable the first semiconductor switching device 416. Therefore, this may enable the first visual notification device 418 to turn on', which in this example may be an LED device. In this example, the first notification device 418 may represent a pass' of the tested device, if it is enabled and, therefore in this example, the first notification device 418 may comprise a green LED.

Further, as the first semiconductor switching device 416 may be enabled, there may be insufficient voltage to enable the second semiconductor switching device 420, which may result in the second visual notification device 422 and audible notification device 424 being disabled.

In another example, a further electrically insulated instrument and/or cable may be operably coupled to the dual output node 412. However, in this example, the dielectric layer of the electrically insulated instrument and/or cable may be damaged. For example, there may be one or more microscopic defects within the dielectric layer of the electrically insulated instrument and/or cable, which may comprise one or more of a crack, blow hole, burr, air bubble or inclusion.

In this example, as discussed previously, the damaged dielectric layer of the electrically insulated instrument and/or cable 316 may be operably coupled to the dual output node 412, and positioned within the electrolyte in order to allow the electrolyte to contact substantially the entire surface of the insulated instrument or cable. However, in this example, if a high voltage output from the supply voltage 408, for example up to a 4.5kV output, is applied to the dual output node 412, a positive current flow between the damaged dielectric layer of the electrically insulated instrument and/or cable 316 and the electrolyte solution 320 (negative) may occur. In some examples, the resultant current flow may, and in some examples will, produce a loading effect on the high voltage supply 408 and the dual output node 412.

In some examples, which may be dependent on the volume of electrolyte solution 320 surrounding the damaged dielectric layer of the electrically insulated instrument and/or cable, the loading effect may be representational of a load of around 1 OOk-SOOk ohms.

The loading effect on the high voltage supply 408 may result in a reduced output voltage at the dual output node 412, wherein a representation of this reduced output voltage may be provided by the potentialdivider4l4tothegate ofthe firstsemiconductorswitching device 416.

-15 -Due to the loading effect caused by the damaged dielectric layer of the electrically insulated instrument and/or cable conducting with the electrolyte solution 320, the reduced representation of the output voltage may be below a threshold voltage required to enable the first semiconductor switching device 416. Subsequently, the first semiconductor switching device 416 may be disabled, or turn off S if previously enabled, thereby disabling the first visual notification device 418. Further, the gate of the second semiconductor switching device 420 may now receive a voltage above its threshold voltage, thereby resulting in the second semiconductor switching device turning on'. In response to this, the second visual notification device 422 and the audible notification device may be enabled.

In this example, as the second visual notification device 422 may relate to a defect within the dielectric layer of the electrically insulated instrument and/or cable, it may comprise a red LED.

If, subsequently, the damaged dielectric layer of the electrically insulated instrument and/or cable is removed from the electrolyte solution, there may no longer be any current flow between the damaged dielectric layer of the electrically insulated instrument and/or cable and the electrolyte solution.

Therefore, the previous loading condition on the supply voltage 408 may cease, and a suitable threshold voltage may be operably coupled to the gate of the first semiconductor switching device 416.

An advantage of utilising some or all of the abovementioned examples of the invention may be that a surface of an electrically insulated instrument and/or cable 316 may be completely in contact with the electrolyte solution 320. This may result in a faster and more efficient testing regime compared to the current testing of electrically insulated instrument and/or cable devices.

Furthermore, utilising some or all of the abovementioned examples of the invention may reduce operator error, as an operator may only be required to immerse an electrically insulated instrument and/or cable in the electrolyte solution for a test to be performed. This may reduce a possibility of an operator forgetting to pass one or more portions of the surface of the electrically insulated instrument and/or cable through a brush electrode, which may result in a defective electrically insulated instrument and/or cable 316 being approved by the operator.

Further, in the current testing of electrically insulated instrument and/or cable devices, a likelihood of sparking between a brush electrode and the electrically insulated instrument and/or cable is relatively common. Usually, the sparking is caused by a defect within the dielectric layer of the insulated instrument and/or cable. It is common for the sparking to generate enough heat to reflow the dielectric layer of the insulated instrument and/or cable, which can partially cover the defect. This partial covering is generally not regarded as being sufficient for the electrically insulated instrument and/or cable to be passed' for use. However, the partial covering may be sufficient to not enable contact between a brush electrode and the partial covered defect, thereby resulting in an incorrect pass' result utilising current testing methods. Such an issue may not occur utilising some examples of the invention, as substantially the entire surface of the insulated instrument may be surrounded by a conductive electrolyte solution.

-16 -Referring to FIG. 5, a flow chart 500 illustrating an operation of a dielectric testing device, according to some examples of the invention, is shown.

Initially, at 501 a device to be tested, for example an electrically insulated instrument and/or cable, such as electrically insulated instrument and/or cable 316 from FIG. 3, may be operably coupled to an output connector of a dielectric testing device. In some examples, one or more insulating sleeves may be positioned on one or more non-insulated active electrode tips of the electrically insulated instrument and/or cable. This may be performed in order to allow the dielectric portion(s) of the electrically insulated instrument and/or cable to be tested for defects.

In some examples, an electrolyte solution, such as electrolyte solution 320 of FIG. 3, may be positioned within a fluid container of the dielectric testing device prior to testing the device.

At 503, the device to be tested may be operably coupled to an output connector of the dielectric testing device and be positioned within the electrolyte solution. In some examples, the entire surface of the device to be tested may be immersed within the electrolyte solution. In some other examples, only a part of the device to be tested may be immersed within the electrolyte solution. For example, if it is determined that the device does comprise a fault, an operator may selectively immerse the device to be tested in order to determine an area where the fault may be located.

At 505, a test voltage may be enabled and operably coupled via the output connector of the dielectric testing device to the device to be tested, which in this example may be immersed within the electrolyte solution. In some examples, the test voltage may be a DC voltage up to around 3.5kv.

At 507, circuitry within the dielectric testing device may receive a representation of the test voltage operably coupled to the device to be tested in order to determine whether the test voltage is representative of a loading effect. In some examples, the circuitry may comprise comparison logic and/or semiconductor switching devices, in order to determine whether the test voltage is representative of a loading effect, wherein in some examples determining whether the test voltage is representative of a loading effect may involve comparing the test voltage with a reference value and/or threshold value.

If it is determined at 507 that the representation of the test voltage operably coupled to the device to be tested is below a threshold value and/or representative of a loading effect, the dielectric testing device may, at 509, enable a visual notification device and/or an audible notification device. In some examples, determining at 507 that the test voltage is below a threshold value may relate to the device being tested comprising one or more defects. Therefore, in some examples, enabling the visual notification device and/or the audible notification device may inform an operator that the device being tested comprises one or more defects within its dielectric layer.

-17 -Subsequently, the operator may mark the tested device as unsuitable, or failed, and return to 501, wherein a further device to be tested may be coupled to the output of the dielectric testing device.

If it is determined at 507 that the test voltage is above the threshold value and/or not representative of a loading effect, the dielectric testing device may, at 511, enable a further visual notification device. In some examples, determining at 507 that the test voltage is above a threshold value may relate to the device being tested not comprising any detectable defects. Therefore, in some examples, enabling the further visual notification device may inform the operator that the device being tested does not comprise any detectable defects within its dielectric layer.

Subsequently, the operator may mark the tested device as suitable, or passed', and return to 501, wherein a further device to be tested may be coupled to the output of the dielectric testing device.

In some examples, utilising one or more examples of the invention may enhance patient and operator safety. In some examples, references to a medical instrument, electrically insulated instrument or cable, and diathermy device may be used interchangeably.

In some examples, references to a partially submerged device, for example a medical instrument, may refer to at least a portion of the submerged device's dielectric layer being in contact with a solution. Further, in some examples, the at least a portion of the submerged device's dielectric layer may comprise one or more sleeved metal tips.

In some examples, references to the solution may refer to any electrically conductive solution.

Further, the terms electrolyte solution and electrically conductive solution may be interchangeable.

For example, an electrolyte solution may be any solution that comprises an ionizing solvent and a substance that ionizes with the ionizing solvent. For example, an ionizing solvent may be water and an example of a substance that ionizes with the ionizing solvent may be most soluble salts, acids and bases.

In some examples, an example of an electrolyte solution may be filtered tap water, which in some examples may comprise an additional wetting agent to further enhance contact with the surface area of a device to be tested.

In some examples, references to a received representation of a test voltage supplied to a medical instrument may relate to a voltage reduced representation of the test voltage supplied to the medical instrument. For example, the received representation of the test voltage supplied to the medical instrument may pass via a resistive divider circuit, in order to reduce the magnitude of the voltage.

In some examples, references to determining whether a received representation of a test voltage is representative of a loading effect may relate to comparing the received representation of the test voltage with a reference voltage, wherein the reference voltage may be considered as a threshold voltage that may be predefined.

-18 -In some other examples, references to determining whether a received representation of a test voltage is representative of a loading effect may relate to enabling a threshold voltage of one or more semiconductor switching devices, wherein the threshold voltage of the one or more semiconductor switching devices may be predefined.

In some examples, a loading effect may relate to an increased loading condition on the voltage supply arranged to supply a test voltage to a medical instrument to be tested. In some examples, an increased loading condition may cause a voltage drop at the output of the voltage supply arranged to supply the test voltage to the medical instrument. In some examples, the voltage drop may be caused by a reduced resistance caused by a defect in a dielectric layer of the medical instrument allowing a conductive portion of the medical instrument to conduct with an electrically conductive solution. In some examples, a positive current may flow from the conductive portion of the medical instrument to the solution, wherein the solution may be housed in a fluid container operably coupled to a negative high voltage.

In the foregoing specification, the invention has been described with reference to specific examples of embodiments of the invention. It will, however, be evident that various modifications and changes may be made therein without departing from the scope of the invention as set forth in the appended claims and that the claims are not limited to the specific examples described above.

The connections as discussed herein may be any type of connection suitable to transfer signals from or to the respective nodes, units or devices, for example via intermediate devices. Accordingly, unless implied or stated otherwise, the connections may for example be direct connections or indirect connections. The connections may be illustrated or described in reference to being a single connection, a plurality of connections, unidirectional connections, or bidirectional connections.

However, different embodiments may vary the implementation of the connections. For example, separate unidirectional connections may be used rather than bidirectional connections and vice versa.

Also, plurality of connections may be replaced with a single connection that transfers multiple signals serially or in a time multiplexed manner. Likewise, single connections carrying multiple signals may be separated out into various different connections carrying subsets of these signals. Therefore, many options exist for transferring signals.

Although specific conductivity types or polarity of potentials have been described in the examples, it will be appreciated that conductivity types and polarities of potentials may be reversed.

Each signal described herein may be designed as positive or negative logic. In the case of a negative logic signal, the signal is active low where the logically true state corresponds to a logic level zero. In the case of a positive logic signal, the signal is active high where the logically true state corresponds to a logic level one. Note that any of the signals described herein can be designed as either negative or positive logic signals. Therefore, in alternate embodiments, those signals described as positive logic signals may be implemented as negative logic signals, and those signals described as negative logic signals may be implemented as positive logic signals.

-19 -Those skilled in the art will recognize that the boundaries between logic blocks are merely illustrative and that alternative embodiments may merge logic blocks or circuit elements or impose an alternate decomposition of functionality upon various logic blocks or circuit elements. Thus, it is to be understood that the architectures depicted herein are merely exemplary, and that in fact many other architectures can be implemented which achieve the same functionality.

Claims

Claims: 1. A medical instrument testing circuit for testing a dielectric integrity of a medical instrument, the medical instrument testing circuit comprising: an output connector arranged to supply a test voltage to a medical instrument at least partially submerged in a solution; and a detection circuit operably coupled to the output connector and arranged to: receive a representation of the test voltage supplied to the medical instrument at least partially submerged in the solution; and determine whether the received representation of the test voltage supplied to the medical instrument at least partially submerged in the solution is representative of a loading effect due to the dielectric integrity of the medical instrument.
2. The medical instrument testing circuit of Claim 1, wherein the detection circuit is further operable to compare the received representation of the test voltage supplied to the medical instrument at least partially submerged in the solution with a threshold value representative of a loading effect.
3. The medical instrument testing circuit of Claims 1 or2, wherein the detection circuit is further operable to output a first control signal when the test voltage supplied to the medical instrument at least partially submerged in the solution is not representative of the loading effect.
4. The medical instrument testing circuit of Claim 3, wherein the first control signal is operable to selectively enable only a first visual notification device.
5. The medical instrument testing circuit of Claims 1 012, wherein the detection circuit is further operable to output a second control signal when the test voltage supplied to the medical instrument at least partially submerged in the solution is representative of the loading effect.
6. The medical instrument testing circuit of Claim 5, wherein the second control signal is operable to selectively enable at least one of: a second visual notification device, an audible notification device.
7. The medical instrument testing circuit of any preceding Claim, wherein the detection circuit comprises a comparison module operable to compare a reference voltage received from the medical instrument testing circuit with the representation of the test voltage supplied to the medical instrument at least partially submerged in the solution.
3. The medical instrument testing circuit of any of preceding Claims ito 7, wherein the detection circuit comprises a first semiconductor switching device operable to receive the representation of the -21 -test voltage supplied to the medical instrument at least partially submerged in the solution and a second semiconductor switching device operably coupled to an output of the first semiconductor switching device.
9. The medical instrument testing circuit of Claim 8, wherein the first semiconductor switching device is enabled and the second semiconductor switching device is disabled when the representation of the test voltage supplied to the medical instrument at least partially submerged in the solution is not representative of the loading effect.
10. The medical instrument testing circuit of Claim 8, wherein the first semiconductor switching device is disabled and the second semiconductor switching device is enabled when the representation of the test voltage supplied to the medical instrument at least partially submerged in the solution is representative of the loading effect.
11. The medical instrument testing circuit of any preceding Claim, wherein the medical instrument comprises a first conductive layer and a second dielectric layer.
12. The medical instrument testing circuit of any preceding Claim, wherein the medical instrument is an electro-surgical medical instrument.
13. The medical instrument testing circuit of any preceding Claim, wherein the solution is an electrically conductive solution
14. The medical instrument testing circuit of Claim 13, wherein the electrically conductive solution comprises filtered water and a wetting agent.
15. A medical instrument testing system for testing the dielectric integrity of a medical instrument, the medical instrument testing system comprising: the medical instrument testing circuit of any preceding Claim; and a fluid container operably coupled to the medical instrument testing circuit; wherein, the fluid container is operable to house a solution for receiving the at least partially submerged medical instrument.
16. A method of testing a dielectric integrity of a medical instrument, comprising: supplying a test voltage to a medical instrument at least partially submerged in a solution; detecting a representation of the test voltage supplied to the medical instrument at least partially submerged in the solution; and determining whether the representation of the test voltage supplied to the medical instrument at least partially submerged in the solution is representative of a loading effect due to the dielectric integrity of the medical instrument.-22 -
17. The method according to Claim 16, further comprising detecting a reduced representation of the test voltage supplied to the medical instrument at least partially submerged in the solution that is indicative of a fault in the dielectric integrity of the medical instrument.
18. The method according to Claim 17 wherein detecting a reduced representation of the test voltage supplied to the medical instrument at least partially submerged in the solution may be a result of a positive current flowing from the medical instrument at least partially submerged in the solution to the solution.
19. The method according to Claim 18, wherein the positive current flowing from the medical instrument at least partially submerged in the solution to the solution reduces the received representation of the test voltage supplied to the medical instrument at least partially submerged in the solution.
20. The medical instrument testing circuit substantially as herein before described with reference to the drawings.