Electrosurgical instrument

Abstract

The invention provides an electrosurgical instrument for electroporation of a biological tissue, the electrosurgical instrument comprising: a transmission line for conveying electromagnetic energy having an electroporation waveform; a radiating tip electrically connected to the transmission line so as to receive the electroporation waveform from the transmission line to thereby generate an electric field across the biological tissue for electroporation of the biological tissue, the radiating tip comprising one or more electrode pairs, each electrode pair comprising: a first electrode; and a second electrode, wherein the first electrode and the second electrode define a cavity therebetween for receiving the biological tissue.

Description

[0001] Electrosurgical instrument

[0002] Field of the Invention

[0003] The present invention relates to electrosurgical instruments and particularly, although not exclusively, to electrosurgical instruments for electroporation of a biological tissue.

[0004] Background

[0005] A wide variety of medical procedures and microbiological processes require the delivery of matter, such as chemical compounds, pharmaceuticals, electrode arrays, DNA and the like, to a cell or group of cells. However, the cell membrane presents a barrier to the introduction of such matter to the desired cells. In particular, the lipid bilayer prevents highly charged molecules, such as DNA, from passing into cells.

[0006] Electroporation, also known as electropermeablilization, is a technique in which an electrical field is applied to cells in order to increase the permeability of the cell membrane. Electroporation has been found to be approximately ten times more effective in increasing the permeability of the cell membrane.

[0007] Typical parameters for achieving electroporation are in the range of 300 - 400mV for < 1ms across the cell membrane. Upon the application of the electric field the cell membrane charges, behaving similarly to a capacitor, and once the critical electric field is achieved, there is a rapid localized rearrangement in lipid morphology, increasing the permeability of the cell membrane.

[0008] It should be noted that the potential difference of 300 - 400mV stated above is the potential difference across the cell membrane; however, it is rarely possible to generate a potential difference localised to be only across the cell membrane. Therefore, in order to achieve this potential difference in most applications requires an extremely strong electric field is required, with a potential difference in the order of 200V / cm, which can quickly lead to potential differences of >1 kV being applied.

[0009] Typically, medical electroporation is performed by locating an electrode internally within the patient and placing a separate return electrode external to the patient, for example on the skin of the patient, in order to generate an electric field across a treatment region. However, such an arrangement, where electrode separation frequency exceeds 5cm, required very strong (>1 kV potential difference) electric fields to be generated in order to achieve electroporation.

[0010] The present invention has been devised in light of the above considerations.

[0011] Summary of the Invention

[0012] At its most general, the invention provides an electrosurgical instrument capable of electroporation in a minimally invasively manner with reduced voltage requirements. The electrosurgical instrument may be conveyed through an instrument channel of a surgical scoping device (e.g. an endoscope, gastroscope, bronchoscope or the like) to enable the instrument to be transported to the treatment site in a non- percutaneous manner. 008582645

[0013] 2

[0014] According to the present disclosure, there is provided an electrosurgical instrument for electroporation of a biological tissue, the electrosurgical instrument comprising: a transmission line for conveying electromagnetic energy having an electroporation waveform; a radiating tip electrically connected to the transmission line so as to receive the electroporation waveform from the transmission line to thereby generate an electric field across the biological tissue for electroporation of the biological tissue, the radiating tip comprising one or more electrode pairs, each electrode pair comprising: a first electrode; and a second electrode, wherein the first electrode and the second electrode define a cavity therebetween for receiving the biological tissue.

[0015] The invention provides a means of generating an electric field across a biological tissue for focused electroporation of the biological tissue.

[0016] In other words, the invention provides a means of electroporation of a biological tissue between two electrodes positioned around the biological tissue. That is, the two electrodes are positioned substantially close to or adjacent to, for example, in contact with, the biological tissue.

[0017] Put another way, there is provided a means of causing electroporation in a biological tissue with a lower input voltage by locating a pair of electrodes either side of the target biological tissue as opposed to locating a separate return electrode spaced apart from the biological tissue.

[0018] By locating a biological tissue for electroporation between two electrodes, for example, using the electrodes to grasp the tissue therebetween, the electric field density required to cause electroporation may be achieved using a significantly lower voltage compared to conventional electroporation systems in which the electrodes are spaced further from the tissue, thereby improving the safety of the electroporation procedure.

[0019] Further, by generating the electric field across the biological tissue, i.e. , between the two electrodes where the biological tissue is received, the electroporation effect may penetrate further into the biological tissue compared to electroporation systems that generate the electric field at a surface of a biological tissue.

[0020] An advantage of the instrument is that no separate return pad is required which, in use, provides one electrode external to the patient, whilst the instrument of the prior art contains the other electrode to generate the electric field therebetween. In contrast, the instrument of the invention provides both electrodes, i.e., the electrode pair, directly around the biological tissue to be treated, thereby enabling a significantly lower voltage to be used in generating the electric field whilst still causing electroporation in the biological tissue.

[0021] The first electrode and the second electrode may be longitudinally extending conductors (e.g. elongate conductors or wires), which extend or protrude from the distal end of the electrosurgical instrument.

[0022] The first electrode and the second electrode define a cavity (or space or gap) therebetween for receiving the biological tissue. When the radiating tip receives the electroporation waveform for generating the 008582645

[0023] 3 electric field, the electric field is generated between the first and second electrodes and across the cavity. Accordingly, the electric field is generated across, i.e., immediately across, a biological tissue received in the cavity between the first and second electrode.

[0024] A biological tissue received in the cavity may be at least partially surrounded , flanked, or encompassed or enveloped, by the first and second electrode, i.e., by the electrode pair.

[0025] The electrosurgical instrument may further comprise a protective sheath for housing the transmission line, and the instrument may be moveable between: a retracted configuration where a radiating portion of the one or more electrode pairs is housed within the protective sheath to prevent the radiating portion of the one or more electrode pairs from contacting the biological tissue; and a deployed configuration where the radiating portion of the one or more electrode pairs is deployed outside the protective sheath from a distal end of the protective sheath to form the cavity for receiving the biological tissue between the first electrode and the second electrode.

[0026] In this way, the one or more electrode pairs may be housed within the protective sheath as the electrosurgical instrument is being manoeuvred to the treatment site, thereby preventing damage to both the electrode pairs and the surrounding tissue.

[0027] The radiating portion of the one or more electrodes pairs, may comprise a distal end portion of the one or more electrodes pairs.

[0028] The instrument may move between the retracted and the deployed configuration through the relative movement of the radiating tip and the protective sheath. For example, the radiating tip may slide back and forth within the protective sheath, such that the radiating tip slides out of the distal end of the protective sheath to occupy the deployed configuration and into the distal end of the protective sheath to occupy the retracted configuration. In an alternative example, the protective sheath may slide back and forth over the radiating tip, such that the protective sheath exposes the radiating tip from the distal end of the protective sheath to occupy the deployed configuration and the protective sheath envelops the radiating tip to occupy the retracted configuration. Any combination of movements of the radiating tip and of the protective sheath may be implemented to move the instrument between the deployed and retracted configurations.

[0029] The radiating tip may further be moveable to a partially retracted position from the deployed position to bring the first and second electrodes together to define a smaller cavity between the first and second electrodes.

[0030] In this way, the one or more electrode pairs may be deployed around the biological tissue in the deployed configuration and then moved to the partially retracted position to contact, grasp, or grip the biological tissue with the first and second electrodes.

[0031] In use, the electrosurgical instrument may be manipulated into a position proximate the biological tissue in the retracted configuration. In this way, damage to both the surrounding tissue and the electrodes may be prevented. When the electrosurgical instrument is in position proximate the biological tissue, the instrument 008582645

[0032] 4 may be moved to the deployed configuration such that the first and second electrodes are positioned loosely around, i.e., on opposing sides of, the biological tissue. The instrument may then be moved to the partially retracted position to shrink the cavity between the first electrode and the second electrode, in order to grip the biological tissue received in the cavity.

[0033] The first and second electrodes may be formed of a shape-memory material, and wherein the first and second electrodes adopt a predetermined geometry in the deployed configuration and deform from the predetermined geometry when moving from the deployed configuration to the retracted configuration.

[0034] In this way, the first and second electrodes may automatically adopt a preferred geometry upon being deployed without requiring further input from the user, thereby simplifying use of the device. For example, the predetermined geometry of the first and second electrodes may define a cavity having a predetermined, or preferable, shape for receiving the biological tissue.

[0035] In an example, the predetermined geometry is substantially pincer shaped. In this way, the radiating tip, and in particular the electrodes, may adopt a pincer shape on deployment. In this way, the electrodes may automatically adopt an arrangement for intuitively surrounding the biological tissue without requiring further input from the user, thereby simplifying use of the device. The predetermined geometry may also be referred to as substantially claw-shaped. Each electrode may adopt a sigmoidal shape in order to form the pincer / claw shape on deployment.

[0036] Put another way, the predetermined geometry may be such that, in a first portion of the first and second electrodes extending between a proximal end and a mid-point of the portion of the first and second electrodes located distally of the distal end of the protective sheath, the first and second electrodes diverge in a curve away from a longitudinal axis of the electrosurgical instrument and, in a second portion of the first and second electrodes extending between the mid-point and a distal end of the portion of the first and second electrodes located distally of the distal end of the protective sheath, the first and second electrodes converge on a line parallel to, but radially offset from, the longitudinal axis of the electrosurgical instrument.

[0037] The electrosurgical instrument may further comprise an insert provided at a distal end portion of the sheath, and wherein the insert comprises one or more channel pairs, each channel pair comprising: a first channel for slidably receiving the first electrode; and a second channel for slidably receiving the second electrode.

[0038] In this way, the relative positions of the electrodes may be made more secure (e.g. predictable, repeatable, consistent), thereby improving the accuracy of the control of the deployment of the electrodes as well as the robustness of the radiating tip.

[0039] In the retracted configuration, a distal end of the first and second electrodes may remain within, or enclosed by, the first and second channels, respectively. In other words, the first and second electrodes may remain slidably received within the first and second channels when housed within the protective sheath. In the deployed configuration, a proximal end of the first and second electrodes, opposite the distal end, may remain within, or enclosed by, the first and second channels respectively. 008582645

[0040] 5

[0041] The first and second channels may have any suitable cross-section and dimensions to accommodate the first and second electrodes. For example, the first and second channels may have a circular, or substantially circular, cross-section having a diameter sufficiently greater than the diameter of the first and second electrodes so as to facilitate sliding of the electrodes in the channels.

[0042] The first and second channels may be shaped to assist the first and second electrodes in adopting the predetermined geometry when moving from the retracted configuration to the deployed configuration.

[0043] For example, the first channel and the second channel may be angled with respect to a longitudinal axis of the sheath such that the first and second channels diverge from the longitudinal axis towards the distal end of the sheath and converge towards the longitudinal axis towards a proximal end of the sheath.

[0044] In this way, the electrodes may be encouraged, urged or caused to (e.g. automatically) splay or spread as the radiating tip is deployed. Accordingly, the electrodes may be deployed about a biological tissue closer to the distal end of the sheath than may otherwise be possible, thereby improving the usability of the instrument in more space limited scenarios.

[0045] The electrosurgical instrument may further comprise a control mechanism adapted to move the instrument between the retracted and deployed configurations in response to a user actuation. In this way, the user may remotely control the deployment and retraction of the radiating tip from and into the sheath.

[0046] The control mechanism may be provided at a proximal end of the transmission line to be accessible to the user. For example, the control mechanism may be provided within a handle of the electrosurgical instrument which is mounted at a proximal end of the transmission line, the handle to be held by the user when operating the electrosurgical instrument. The handle may be held by the user to control how the electrosurgical instrument is manipulated when being moved to and from the treatment site, i.e., towards or away from the biological tissue being treated.

[0047] The control mechanism may comprise a mechanical control mechanism, such as a control handle, trigger, or lever, or dial, that may be actuated by the user for moving the radiating tip between the deployed and retracted configurations.

[0048] For example, the control mechanism may comprise a lever connected to a push rod or control wire, such that an actuation of the lever in a first direction pushes the first and second electrodes out of the protective sheath to move the radiating tip to the deployed configuration and an actuation of the lever in a second (e.g. opposite) direction, pulls the first and second electrodes into the protective sheath to move the radiating tip to the retracted configuration.

[0049] In an alternative example, the control mechanism may comprise a lever connected to a push rod or control wire, such that an actuation of the lever in a first direction pulls the protective sheath towards the proximal end of the electrosurgical instrument to expose the first and second electrodes to move the radiating tip to the deployed configuration and an actuation of the lever in a second (e.g. opposite) direction, pushes the protective sheath towards the distal end of the electrosurgical instrument to cover the first and second electrodes to move the radiating tip to the retracted configuration. 008582645

[0050] 6

[0051] The control mechanism may comprise an electronic control mechanism, such as a switch, a button, a touch sensor and the like.

[0052] The electrosurgical instrument may comprise a motor adapted to move the instrument between the retracted and deployed configurations in response to the user actuation.

[0053] For example, the control mechanism may comprise a button connected to the motor, such that an actuation of the button activates the motor to drive, or push, the first and second electrodes out of the protective sheath to move the radiating tip to the deployed configuration and a further actuation of the button activates the motor to drive, or pull, the first and second electrodes into the protective sheath to move the radiating tip to the retracted configuration.

[0054] In an alternative example, the control mechanism may comprise a button connected to the motor, such that an actuation of the button activates the motor to drive, or pull, the protective sheath towards the proximal end of the electrosurgical instrument to expose the first and second electrodes to move the radiating tip to the deployed configuration and a further actuation of the button activates the motor to drive, or push, the protective sheath towards the distal end of the electrosurgical instrument to cover the first and second electrodes to move the radiating tip to the retracted configuration.

[0055] In some examples, in response to a user actuation when the instrument is in the retracted configuration, the motor is adapted to move the electrosurgical instrument from the retracted configuration to the deployed configuration in a first movement and then move the electrosurgical instrument from the deployed configuration to the partially retracted configuration in a second movement.

[0056] For example, the control mechanism may comprise a button connected to the motor, such that an actuation of the button activates the motor to drive, or push, the first and second electrodes out of the protective sheath to move the radiating tip to the deployed configuration in a first motion. A further actuation of the button activates the motor to drive, or pull, the first and second electrodes partially into the protective sheath to move the radiating tip to the partially retracted configuration in a second motion, for example to reduce the size of the cavity between the first and second electrodes to grip the biological tissue.

[0057] In an alternative example, the control mechanism may comprise a button connected to the motor, such that an actuation of the button activates the motor to drive, or pull, the protective sheath towards the proximal end of the electrosurgical instrument to expose the first and second electrodes to move the radiating tip to the deployed configuration in a first motion. A further actuation of the button activates the motor to drive, or push, the protective sheath towards the distal end of the electrosurgical instrument to partially cover the first and second electrodes to move the radiating tip to the partially retracted configuration in a second motion, for example to reduce the size of the cavity between the first and second electrodes to grip the biological tissue.

[0058] In some further examples, in response to a user actuation when the instrument is in the partially retracted configuration, the motor is adapted to move the electrosurgical instrument from the partially retracted configuration to the deployed configuration in a first movement and then move the electrosurgical instrument from the deployed configuration to the retracted configuration in a second movement. 008582645

[0059] 7

[0060] For example, the control mechanism may comprise a button connected to the motor, such that an actuation of the button activates the motor to drive, or push, the first and second electrodes out of the protective sheath to move the radiating tip from the partially retracted configuration to the deployed configuration in a first motion, for example to increase the size of the cavity between the first and second electrodes to release the gripped biological tissue. A further actuation of the button activates the motor to drive, or pull, the first and second electrodes fully into the protective sheath to move the radiating tip to the retracted configuration in a second motion.

[0061] In an alternative example, the control mechanism may comprise a button connected to the motor, such that an actuation of the button activates the motor to drive, or pull, the protective sheath towards the proximal end of the electrosurgical instrument to expose the first and second electrodes to move the radiating tip from the partially retracted configuration to the deployed configuration in a first motion, for example to increase the size of the cavity between the first and second electrodes to release the gripped biological tissue. A further actuation of the button activates the motor to drive, or push, the protective sheath towards the distal end of the electrosurgical instrument to cover the first and second electrodes to move the radiating tip to the retracted configuration in a second motion.

[0062] The electrosurgical instrument may further comprise a switch adapted to prevent electromagnetic energy being conveyed to the radiating tip when the radiating tip is in the retracted configuration.

[0063] In this way, the electrodes may be prevented from receiving electromagnetic energy when in close proximity with each other, thereby preventing, or reducing the chance of, a short-circuit between the first and second electrodes. The switch may be a mechanical switch linked to the movement of the radiating tip between the deployed configuration and the retracted configuration, such that the switch is actuated to prevent electromagnetic energy being conveyed to the radiating tip when the radiating tip moves towards the retracted configuration and such that the switch is actuated to permit electromagnetic energy being conveyed to the radiating tip when the radiating tip moves towards the deployed configuration.

[0064] The switch may be an electrical switch linked to the change in proximity of the first and second electrodes between the deployed configuration and the retracted configuration, such that the switch is actuated to prevent electromagnetic energy being conveyed to the radiating tip when the radiating tip moves towards the retracted configuration and the distance between the first and second electrodes decreases and such that the switch is actuated to permit electromagnetic energy being conveyed to the radiating tip when the radiating tip moves towards the deployed configuration and the distance between the first and second electrodes increases. The electrical switch may be controlled by way of a controller as described in more detail below.

[0065] The radiating tip may comprise one or more insulating sleeves, wherein each of the one or more insulating sleeves is provided around a respective electrode of the electrode pairs, and wherein each of the one or more insulating sleeves extends along a proximal portion of the respective electrode leaving a distal portion of the respective electrode exposed to contact the biological tissue. 008582645

[0066] 8

[0067] In this way, the shape and extent of the electric field generated between the first and second electrodes may be controlled with greater accuracy because a spacing between exposed electrode portions can be made more reliably consistent. In addition, the insulating sleeve may prevent a short-circuit from occurring between the proximal portions of the first and second electrodes, which may be closer together than the distal portions of the first and second electrodes according to the predetermined geometry of the first and second electrodes. The insulating sleeves may be formed from any suitable insulating material.

[0068] The radiating tip may comprise a plurality of electrode pairs. For example, the radiating tip may comprise four electrode pairs, i.e., four first electrodes and four second electrodes. Each electrode pair defines a cavity between the respective first and second electrode. Each cavity between each respective pair of first and second electrodes may be the same, or substantially the same, size or one or more of the cavities may have a different size. Put another way, the cavity between the set of first electrodes and the set of second electrodes may be uniform or the cavity between the set of first electrodes and the set of second electrodes may vary.

[0069] By providing a plurality of electrode pairs, the strength of the electric field, and the electroporation area, may be increased. By controlling the spacing between the first and second electrodes of each of the electrode pairs, the electric field may be made more consistent or may be shaped according to the application.

[0070] Each electrode pair may moveable between the deployed configuration and the retracted configuration independently. For example, each electrode pair may be provided with a control mechanism as described above in order to deploy and retract each electrode pair independently of the other electrode pairs.

[0071] Alternatively, all of the electrode pairs may be deployed and retracted simultaneously.

[0072] The first electrode may comprise: a plurality of first elongate conductors; and one or more first cross connectors coupled between adjacent first elongate conductors, and the second electrode may comprise: a plurality of second elongate conductors; and one or more second cross connectors coupled between adjacent second elongate conductors. Put another way, the first and second electrodes may be mesh electrodes. That is, the plurality of first cross-connectors may electrically connect together the plurality of first elongate conductors, and the plurality of second cross-connectors may electrically connect together the plurality of second elongate conductors.

[0073] In this way, the first and second electrodes may be formed from a resilient, flexible mesh, which may provide a more robust radiating tip.

[0074] The first electrode and the second electrode may each comprise a pointed distal end. In this way, the radiating tip may pierce the biological tissue when deployed in order to perform electroporation internally within the biological tissue, for example within a focused treatment zone.

[0075] The electrosurgical instrument may comprise a retractable wedge extending longitudinally through the protective sheath. The retractable wedge may be adapted to move along a central axis of the electrosurgical instrument. The retractable wedge may comprise a wedge surface adapted to abut against the first and / or second electrode when the retractable wedge is retracted into the protective sheath. The wedge surface 008582645

[0076] 9 may be adapted to translate the movement of the retractable wedge into the protective sheath along the central axis into a wedging force against the first and / or second electrode, wherein a component of the wedging force is directed away from the central axis of the electrosurgical instrument. Put another way, the retractable wedge may be adapted to force the first and second electrodes apart from each other (e.g. to increase a size of the cavity for receiving biological tissue) when the retractable wedge is retracted into the protective sheath. As such, the retractable wedge may provide a mechanism for steering the electrodes as they are pushed out of the protective sheath.

[0077] The electrosurgical instrument may comprise an extendable collar extending longitudinally over the protective sheath. Alternatively, the extendable collar may be provided coaxially within the protective sheath between the protective sheath and the first and second electrodes. The extendable collar may be adapted to move over, or through, the protective sheath along a central axis of the electrosurgical instrument. The extendable collar may comprise a contact surface of adapted to abut against the first and / or second electrode when the extendable collar is extended over or through the protective sheath. The contact surface may be adapted to translate the movement of the extendable collar over or through the protective sheath into a force against the first and / or second electrode, wherein a component of the force is directed towards the central axis of the electrosurgical instrument. Put another way, the extendable collar may be adapted to force the first and second electrodes towards each other when the extendable collar is extended over, or through, the protective sheath. As such, the extendible collar may provide a mechanism for steering the electrodes as they are pushed out of the protective sheath.

[0078] According to an aspect of the invention, there is provided an electrosurgical apparatus for delivering electromagnetic energy to biological tissue at a treatment site, the apparatus comprising: an electrosurgical generator arranged to output a first electroporation waveform; an electrosurgical instrument as described above connected to the electrosurgical generator so as to receive the first electroporation waveform and generate the electric field across the biological tissue, wherein the transmission line is arranged to convey the first electroporation waveform.

[0079] The electroporation waveform may be a pulsed DC current, i.e. , a square wave oscillating between a target voltage and 0V. In use, the voltage at the first electrode may oscillate between the target voltage and 0V and the second electrode may be held at 0V consistently. Alternatively, the voltage at the second electrode may oscillate between the target voltage and 0V and the first electrode may be held at 0V consistently, thereby reversing the direction of the electric field generated across the biological tissue. The direction of the electrical field may be controlled, for example by way of a user input received at a user interface of the electrosurgical instrument and / or the electrosurgical generator. In the case where the radiating tip comprises a plurality of electrode pairs, each of the electrode pairs may receive the same electroporation waveform, or each of the electrode pairs may receive a different electroporation waveform in order to shape the electric field defined by the radiating tip. 008582645

[0080] 10

[0081] The electrosurgical generator may comprise a pulse generator circuit for generating the first electroporation waveform and the pulse generator circuit may comprise one or more rapid switching elements capable of switching ON / OFF a source voltage at the desired frequency.

[0082] The first electroporation waveform may have any one or more of: a pulse width in the range from 1 ns to 10 ms, a pulse amplitude in the range of 10 V to 10 kV, and a duty cycle equal to or less than 50%.

[0083] The electrosurgical generator may be arranged to output a second signal comprising radiofrequency electromagnetic energy for treating (e.g. coagulating or ablating) and / or sensing the biological tissue, and wherein the transmission line is arranged to convey the second signal to the radiating tip.

[0084] The electrosurgical generator may comprise a controller adapted to monitor an electrical characteristic of the second signal; determine or infer a distance between the first and second electrodes based on the electrical characteristic; and generate a control signal to cause the electrosurgical generator to adjust the first electroporation waveform based on the determined or inferred distance between the first and second electrodes.

[0085] The controller may monitor an electrical characteristic of the second signal, such as a current, a voltage, and / or a phase of the second signal (or variations in one or more of those electrical characteristics over time).

[0086] A combination of the current, voltage and / or phase information may be used to infer or calculate a capacitance between the first and second electrodes. As the capacitance is inversely proportional to the distance between a pair of electrodes, this capacitance value may be used to infer the distance between the first and second electrodes.

[0087] As the first and second electrodes approach each other, for example when the instrument is approaching the retracted configuration, the capacitance will increase. Accordingly, a capacitance exceeding a predetermined threshold may be used to prevent the electrosurgical generator from generating the first signal in order to prevent a short circuit between the two electrodes in the retracted configuration.

[0088] As the first and second electrodes move away from each other, for example when the instrument is approaching the deployed configuration, the capacitance will decrease. Accordingly, a capacitance falling below a predetermined threshold may be used to cause the electrosurgical generator to generate the first signal.

[0089] In this way, the electrosurgical apparatus may include a safety shut-off, which reduces the chance of an electrical short circuit (e.g. an arc) between the first and second electrodes when the instrument is approaching and / or in the retracted configuration, and the two electrodes move physically closer to each other. Also, in this way, the electrosurgical apparatus may adapt the energy delivered to the biological tissue according to the tissue thickness in order to ensure electroporation is achieved throughout the biological tissue received between the electrodes. 008582645

[0090] 11

[0091] The electrosurgical generator may comprise a switch adapted to prevent electromagnetic energy being conveyed to the radiating tip when the radiating tip is in the retracted configuration.

[0092] In this way, the electrodes may be prevented from receiving electromagnetic energy when in close proximity with each other, thereby preventing a short-circuit between the first and second electrodes.

[0093] The switch may be a mechanical switch linked to the movement of the radiating tip between the deployed configuration and the retracted configuration, such that the switch is actuated to prevent electromagnetic energy being conveyed to the radiating tip when the radiating tip moves towards the retracted configuration and such that the switch is actuated to permit electromagnetic energy being conveyed to the radiating tip when the radiating tip moves towards the deployed configuration.

[0094] The switch may be an electrical switch linked to the change in proximity of the first and second electrodes between the deployed configuration and the retracted configuration, such that the switch is actuated to prevent electromagnetic energy being conveyed to the radiating tip when the radiating tip moves towards the retracted configuration and the distance between the first and second electrodes decreases and such that the switch is actuated to permit electromagnetic energy being conveyed to the radiating tip when the radiating tip moves towards the deployed configuration and the distance between the first and second electrodes increases.

[0095] The electrosurgical apparatus may further comprise a surgical scoping device, wherein the radiating tip and the transmission line are dimensioned to be insertable into an instrument channel of the surgical scoping device.

[0096] The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided.

[0097] Summary of the Figures

[0098] Embodiments and experiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures in which:

[0099] Figure 1 shows a schematic representation of an electrosurgical system.

[0100] Figure 2 shows a distal portion of an electrosurgical instrument according to an aspect of the invention.

[0101] Figure 3 shows the electrosurgical instrument shown in Figure 2 provided around a biological tissue.

[0102] Figure 4 shows the electrosurgical instrument shown in Figure 2 generating an electric field across a biological tissue to perform electroporation.

[0103] Figure 5 shows the electrosurgical instrument of Figure 2 moving from a deployed configuration to a retracted configuration.

[0104] Figure 6 shows the electrosurgical instrument of Figure 2 moving from a retracted configuration to a deployed configuration to a partially retracted configuration to grip a biological tissue. 008582645

[0105] 12

[0106] Figure 7A shows an elevation view of an electrosurgical instrument according to an aspect of the invention.

[0107] Figure 7B shows an elevation view of an electrosurgical instrument according to a further aspect of the invention.

[0108] Figure 8 shows an elevation view of an insert provided within a protective sheath of the electrosurgical instrument of Figure 7A.

[0109] Figure 9 shows a cross-section of the insert of Figure 8.

[0110] Figure 10A shows the electrosurgical instrument of Figure 2 in the deployed configuration connected to a motor.

[0111] Figure 10B shows the electrosurgical instrument of Figure 2 in the retracted configuration connected to a motor.

[0112] Figure 11 A shows the electrosurgical instrument of Figure 2 with an additional retractable wedge.

[0113] Figure 11 B shows the electrosurgical instrument of Figure 2 with an additional extendable collar.

[0114] Detailed Description of the Invention

[0115] Aspects and embodiments of the present invention will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference.

[0116] FIG. 1 is a schematic diagram of an electrosurgery system 100 that is capable of supplying an electroporation waveform to the distal end of an invasive electrosurgical instrument. The system 100 comprises a generator 102 for controllably supplying energy for electroporation, for example by way of a pulse generator circuit 101. Energy for electroporation may comprise pulsed or sinusoidal (e.g. continuous wave electromagnetic wave) in the radiofrequency (RF) or low frequency (LF) bands. Herein, reference to RF may mean a frequency in the range of 300 kHz to 300 MHz. Reference to LF may mean a frequency in the range 30 kHz to 300 kHz.

[0117] A suitable generator for this purpose is described in WO 2019 / 185331 A1 , which is incorporated herein by reference. The generator 102 and pulse generator circuit 101 may be arranged to deliver power in a series of pulses as discussed below.

[0118] The generator 102 is connected to an interface joint 106 by an interface cable 104. If needed, the interface joint 106 can house an instrument control mechanism that is operable by sliding a trigger 110, e.g. to control longitudinal (back and forth) movement of one or more control wires or push rods (not shown). If there is a plurality of control wires, there may be multiple sliding triggers on the interface joint to provide full control. The function of the interface joint 106 is to combine the inputs from the generator 102 and instrument control mechanism into a single flexible shaft 112, which extends from the distal end of the interface joint 106. 008582645

[0119] 13

[0120] The interface joint 106 and trigger 110 may be embodied in a handpiece. A suitable handpiece for this purpose is described with reference to Figure 6A and 6B of WO 2019 / 073037 A1 , which is incorporated herein by reference.

[0121] The flexible shaft 112 is insertable through the entire length of an instrument (working) channel of a surgical scoping device 114, such as an endoscope, bronchoscope, gastroscope or the like.

[0122] The surgical scoping device 114 comprises a body 116 having a number of input ports and an output port from which an instrument cord 120 extends. The instrument cord 120 comprises an outer jacket which surrounds a plurality of lumens. The plurality of lumens convey various things from the body 116 to a distal end of the instrument cord 120. One of the plurality of lumens is an instrument channel. Other lumens may include a channel for conveying optical radiation, e.g. to provide illumination at the distal end or to gather images from the distal end. The body 116 may include an eye piece 122 for viewing the distal end. In order to provide illumination at the distal end, a light source 124 (e.g. LED or the like) may be connected to the body 116 by an illumination input port 126.

[0123] The flexible shaft 112 has a distal assembly 118 (not drawn to scale in FIG. 1 ) that is shaped to pass through the instrument channel of the surgical scoping device 114 and protrude (e.g. inside the patient) at the distal end thereof. The distal end assembly includes an electrosurgical instrument for causing electroporation in biological tissue as discussed herein.

[0124] The structure of the distal assembly 118 discussed below may be designed to have a maximum outer diameter equal to or less than 2.0 mm, e.g. less than 1.9 mm (and more preferably less than 1.5 mm) and the length of the flexible shaft can be equal to or greater than 1 .2 m.

[0125] The body 116 includes a power input port 128 for connecting to the flexible shaft, which comprises an energy conveying means, or transmission line, (e.g. a twisted cable pair or the like) for conveying the energy for electroporation.

[0126] As discussed above, it is desirable to be able to control the position of at least the distal end of the instrument cord 120. The body 116 may include a control actuator 130 that is mechanically coupled to the distal end of the instrument cord 120 by one or more control wires (not shown), which extend through the instrument cord 120. The control wires may travel within the instrument channel or within their own dedicated channels. The control actuator 130 may be a lever or rotatable knob, or any other known catheter manipulation device. The manipulation of the instrument cord 120 may be software-assisted, e.g. using a virtual three-dimensional map assembled from computer tomography (CT) images.

[0127] Figure 2 shows an electrosurgical instrument 200 for electroporation of a biological tissue according to an aspect of the invention. The electrosurgical instrument 200 comprises a transmission line 202 for conveying electromagnetic energy having an electroporation waveform, for example from the generator 102, to a radiating tip 204.

[0128] The radiating tip 204 is electrically connected to the transmission line 202 so as to receive the electroporation waveform from the transmission line 202. The radiating tip 204 comprises an electrode pair 206 comprising a first electrode 210 and a second electrode 220. The first electrode 210 and the second 008582645

[0129] 14 electrode 220 define a cavity 225 therebetween for receiving the biological tissue 240 as shown in Figure

[0130] 3.

[0131] In the example shown in Figure 2, the electrosurgical instrument 200 further comprises a protective sheath 230 for housing the transmission line 202.

[0132] Figure 3 shows the electrosurgical instrument 200 of Figure 2, with a biological tissue 240 received in the cavity 225 between the first electrode 210 and the second electrode 220. The biological tissue 240 may be any biological tissue in which electroporation is to be induced, for example: organ tissue; muscle tissue; lung tissue; gastrointestinal tract tissue; and the like. In the example shown in Figure 3, no electric field is being generated between the first electrode 210 and the second electrode 220.

[0133] Figure 4 shows the electrosurgical instrument 200 of Figure 2, with a biological tissue 240 received in the cavity 225 between the first electrode 210 and the second electrode 220. In the example shown in Figure 4, the electroporation waveform has is being delivered to the radiating tip 204 in order to generate an electric field 250 between the first electrode 210 and the second electrode 220, across the cavity 225 and across the biological tissue 240. The electric field 250 is of sufficient strength to cause electroporation to occur in the biological tissue as described in further detail below. As the first 210 and second 220 electrodes are provided directly around the biological tissue 240, as opposed to using a conventional arrangement with a single internal electrode and a return pad external to the patient, the strength of the electric field, and the voltage needed to generate it, for causing electroporation may be significantly lower than conventional arrangements.

[0134] In the example shown in Figure 4, the first electrode 210 and the second electrode 220 each comprise a pointed distal end 255, for example for piecing tissue surrounding the biological tissue 240 or the biological tissue 240 itself.

[0135] In the examples shown in Figures 2 to 4, the first 210 and second 220 electrodes are single elongate conductors with blunt distal ends. In some examples, the first electrode 210 and the second electrode 220 may comprise a pointed distal end for piercing tissue. In some examples, the first 210 and second 220 electrodes may comprise a plurality of elongate conductors and one or more cross connectors coupled between adjacent elongate conductors, thereby forming first and second mesh electrodes.

[0136] Figure 5 shows the electrosurgical instrument 200 of Figure 2 moving from a deployed configuration as shown in view 260, where the radiating portion of the one or more electrode pairs is deployed outside the protective sheath 230 from a distal end of the protective sheath to form the cavity 225 for receiving the biological tissue between the first electrode 210 and the second electrode 220, to a retracted configuration as shown in view 290.

[0137] When the user actuates a control mechanism, which may for example be incorporated into trigger 110, the electrosurgical instrument moves between the deployed configuration shown in view 260 and a retracted configuration, shown in view 290, where the radiating portion of the one or more electrode pairs is housed within the protective sheath 230 to prevent the radiating portion of the one or more electrode pairs from 008582645

[0138] 15 contacting the biological tissue. The control mechanism may be linked to a motor for moving the instrument between the retracted and deployed configurations in response to the user actuation.

[0139] In the sequence shown in Figure 5, the electrosurgical instrument 200 begins in the deployed configuration in view 260 with the first electrode 210 and the second electrode 220 being deployed outside of the protective sheath to define cavity 225.

[0140] In response to a user actuation of the control mechanism, the electrosurgical instrument 200 begins to move from the deployed configuration towards the retracted configuration. It should be noted that in the example shown in Figure 5, this movement is represented as the first 210 and second 220 electrodes being pulled into the protective sheath 230; however, this movement may also be achieved by the protective sheath 230 being pushed over the first 210 and second 220 electrodes.

[0141] As shown in view 270, as the electrosurgical instrument 200 is moved towards the retracted configuration from the deployed configuration, the first 210 and second 220 electrodes deform, for example due to the contact between the electrodes and the protective sheath 230, in order to adopt a geometry suitable for being held within the protective sheath 230.

[0142] As shown in view 280, as the electrosurgical instrument 200 approaches the retracted configuration, the first 210 and second 220 electrodes have deformed to fit entirely within the protective sheath 230. As shown in view 290, the first 210 and second 220 electrodes fit entirely within the protective sheath 230 in the retracted configuration.

[0143] As shown in Figure 5, as the electrosurgical instrument is moved from the deployed configuration shown in view 260 towards the retracted configuration shown in view 290, the space between the first 210 and second 220 electrodes decreases as illustrated in views 270 and 280. In order to avoid arcing between the electrodes, the electrosurgical instrument 200 or the generator 102 further comprises a switch adapted to prevent electromagnetic energy being conveyed to the radiating tip when the radiating tip is in the retracted configuration or has passed a predetermined point travelling between the deployed configuration and the retracted configuration.

[0144] In reverse, the sequence shown in Figure 5 shows the movement of the electrosurgical instrument from the retracted configuration to the deployed configuration shown in view 260.

[0145] In the examples shown in Figures 2 to 5, the first 210 and second 220 electrodes are formed of a shapememory material, such as nitinol. When the instrument is moved to the deployed configuration as shown in view 260 of Figure 5, the first and second electrodes adopt a predetermined geometry and deform from the predetermined geometry when moving from the deployed configuration to the retracted configuration as illustrated in Figure 5. In the examples shown in Figures 2 to 5, the predetermined geometry is substantially pincer shaped.

[0146] Figure 6 shows the electrosurgical instrument 200 of Figure 2 being moved in a sequence to surround and grip a biological tissue 240 between the first 210 and second 220 electrodes. 008582645

[0147] 16

[0148] In the example shown in Figure 6, in response to a user actuation of the control mechanism, when the instrument is in the retracted configuration, the motor moves the electrosurgical instrument 200 from the retracted configuration to the deployed configuration in a first movement. View 292 shows the electrosurgical instrument 200 part of the way through the first movement. View 294 shows the electrosurgical instrument 200 in the deployed configuration after the first movement has been completed.

[0149] In a second movement, the electrosurgical instrument moves from the deployed configuration shown in view 294 to the partially retracted configuration shown in view 296 to reduce the distance between the first 210 and second 220 electrodes and grip the biological material.

[0150] In reverse, the sequence shown in Figure 6 shows the electrosurgical instrument 200 moving from the partially retracted configuration shown in view 296 to the deployed configuration shown in view 294 in a first movement to release the biological tissue 240. In a second movement, the electrosurgical instrument 200 moves from the deployed configuration shown in view 294 to the retracted configuration via the configuration shown in view 292.

[0151] Figure 7 A shows an elevation view of an electrosurgical instrument 300 according to an aspect of the invention.

[0152] In the example shown in Figure 7 A, the electrosurgical instrument 300 comprises a plurality of electrode pairs, each comprising a first electrode 312, 314, 316 and 318 and a corresponding second electrode 322, 324, 326 and 328. The electrosurgical instrument also comprises a protective sheath 330 as described above with reference to Figures 2 to 6.

[0153] In addition, each of the electrodes shown in the example of Figure 7A has an insulating sleeve, 332, 334, 336, 338, 352, 354, 356 and 358 extending along its proximal portion leaving the distal portion of the respective electrode exposed to contact the biological tissue and to generate the electric field therebetween.

[0154] Each electrode pair (312 and 322, 314 and 324, 316 and 326, 318 and 328) in Figure 7A may be moveable between the deployed configuration (shown in Figure 7A) and the retracted configuration independently according to the sequences illustrated in Figures 5 and 6. Alternatively, all of the electrodes shown in Figure 7A may be moveable between the deployed configuration (shown in Figure 7A) and the retracted configuration simultaneously. The electrosurgical instrument may be selectively adjusted to switch between independent and simultaneous deployment according to the preference of the user.

[0155] Figure 7B shows an elevation view of an electrosurgical instrument 360 according to a further aspect of the invention.

[0156] In the example shown in Figure 7B, the first electrode 361 and the second electrode 271 are mesh electrodes. The first electrode 361 comprises a plurality of first elongate conductors 362, 364, 366 and 368 and a plurality of first cross connectors 380 coupled between each of the first elongate conductors 362, 364, 366 and 368. The second electrode 371 comprises a plurality of second elongate conductors 372, 374, 376 and 378 and a plurality of second cross connectors 390 coupled between each of the second elongate conductors 372, 374, 376 and 378. 008582645

[0157] 17

[0158] The electrosurgical instrument 360 also comprises a protective sheath 330 as described above with reference to Figures 2 to 6.

[0159] Each mesh electrode (first electrode 361 and second electrode 371 ) in Figure 7B may be moveable between the deployed configuration (shown in Figure 7B) and the retracted configuration independently according to the sequences illustrated in Figures 5 and 6. Alternatively, both of the electrodes shown in Figure 7B may be moveable between the deployed configuration (shown in Figure 7B) and the retracted configuration simultaneously. The electrosurgical instrument 360 may be selectively adjusted to switch between independent and simultaneous deployment according to the preference of the user.

[0160] Figure 8 shows an elevation view of an insert 400 provided within the protective sheath 330 of the electrosurgical instrument 300 of Figure 7A. Figure 9 shows a cross-section 450 of the insert 400 of Figure 8 taken along line A-A.

[0161] In the example shown in Figure 8, the insert 400 comprises a plurality of channel pairs. Each channel pair comprises a first channel 412, 414, 416 and 418 for slidably receiving a first electrode 312, 314, 316 and 318, respectively. In addition, each channel pair comprises a second channel 422, 424, 426 and 428 for slidably receiving a second electrode 322, 324, 326 and 328, respectively.

[0162] As shown in Figure 9, the first channel 414 and the second channel 424 are angled with respect to a longitudinal axis 460 of the sheath such that the first and second channels diverge from the longitudinal axis towards the distal end 470 of the sheath and converge towards the longitudinal axis towards a proximal end 480 of the sheath .

[0163] Figures 10Aand 10B show the electrosurgical instrument 200 of Figures 2 to 6 in the deployed configuration and the retracted configuration, respectively.

[0164] In the examples shown in Figures 10A and 10B, the first 210 and second 220 electrodes are coupled to a motor 500 adapted to move the electrosurgical instrument 200 between the retracted and deployed configurations in response to a user actuation, for example a user actuation of the trigger 110 as described above.

[0165] The motor 500 may be coupled to both the first 210 and second 220 electrodes, or each of the first 210 and the second 220 electrodes may be provided with an individual motor for controlling the movement of the electrodes independently of each other. As such, the motor 500 may be a motor assembly comprising multiple motors.

[0166] The motor 500 may be coupled to the first 210 and / or second 220 electrode by way of a push rod / pull wire arrangement 510 for translating a movement of the motor 500 into a movement of the first 210 and / or second 220 electrodes between the retracted and deployed configurations.

[0167] In the examples shown in Figures 10A and 10B, the first 210 and second 220 electrodes are electrically connected to the generator 102 by way of a switch 520, which may be provided in the electrosurgical instrument or in the generator. The switch 520 is adapted to close when the instrument is in the deployed configuration as shown in Figure 10A in order to couple the first 210 and second 220 electrodes to the 008582645

[0168] 18 generator 102 in order to deliver the electroporation waveform to the tissue. The switch 520 is further adapted to open when the instrument is in, and approaches, the retracted configuration as shown in Figure 10B in order to decouple the first 210 and second 220 electrodes from the generator 102 in order to prevent delivery of the electroporation waveform to the electrodes and generating an arcing short circuit between the electrodes.

[0169] Figure 11A shows an electrosurgical instrument 600 comprising a retractable wedge 610 extending longitudinally through the protective sheath 230.

[0170] The retractable wedge 610 may be pulled into the protective sheath 230 such that a wedge surface 615 of the retractable wedge 610 abuts against the first 210 and / or second 220 electrode, thereby forcing the first 210 and / or second 220 electrode away from a central axis 605 of the electrosurgical instrument 600 and the electrodes apart from each other. In this way, retracting the retractable wedge 610 to force the electrodes apart may widen the cavity between the first 210 and second 220 electrodes. For example, retraction of the wedge can cause the electrodes to splay apart.

[0171] In the case where the first 210 and second 220 electrodes are formed of a shape memory material, the release of the retractable wedge 610 such that the wedge surface 615 of the retractable wedge 610 no longer abuts against the first 210 and / or second 220 electrode allows the first 210 and / or second 220 electrode to return to their / its original shape, thereby narrowing the cavity between the first 210 and second 220 electrodes.

[0172] Figure 11 B shows an electrosurgical instrument 620 comprising an extendable collar 630 extending longitudinally over the protective sheath 230. In some examples, the extendable collar 630 may be provided coaxially within the protective sheath 230 between the protective sheath 230 and the first 210 and second 220 electrodes.

[0173] The extendable collar 630 may be pushed over, or through, the protective sheath 230 such that a contact surface 635 of the extendable collar 630 abuts against the first 210 and / or second 220 electrode, thereby forcing the first 210 and / or second 220 electrode towards a central axis 605 of the electrosurgical instrument 620 and the electrodes towards each other. In this way, extending the extendable collar 630 to force the electrodes together may decrease the cavity between the first 210 and second 220 electrodes.

[0174] In the case where the first 210 and second 220 electrodes are formed of a shape memory material, the retraction of the extendable collar 630 such that the contact surface 635 of the extendable collar 630 no longer abuts against the first 210 and / or second 220 electrode allows the first 210 and / or second 220 electrode to return to their / its original shape, thereby widening the cavity between the first 210 and second 220 electrodes.

[0175] The energy for electroporation is essentially RF or low frequency (LF) high voltage pulses or bursts of sinusoidal energy configured to open pores in cell membranes. The electrosurgical instrument of the invention may be used in scenario where a therapeutic agent in present in the treatment site, whereby open pores in the cell membrane facilitates or enables the therapeutic agent to enter the cells. In other words, the instrument may be used in conventional electroporation procedures. 008582645

[0176] 19

[0177] Alternatively or additionally, the energy for electroporation may be configured to permanently open pores, thereby to cause irreversible disruption to the cell membrane causing the cells to die. In other words, the instrument can be used for irreversible electroporation (IRE).

[0178] In order to provide the energy for electroporation, the generator may comprise a pulse generator circuit for generating a pulsed or otherwise amplitude varying electrical signal. In one example, the pulse generator circuit may output a continuous wave (e.g. sinusoidal signal) in one or more discrete bursts. In another example, the pulse generator circuit may comprise one or more rapid switching elements (e.g. MOSFET transistors) capable of switching ON / OFF a drain-source voltage at the desired frequency for the electroporation energy. For example, the pulse generator circuit may be based on high voltage (VDSmax>1 kV) power MOSFETs in a push-pull arrangement. In order to charge up the gate-source capacitance and gate-drain capacitances fast enough, the pulse generator circuit may include gate drivers that can source high enough current to charge up the input capacitances.

[0179] In one example, the pulse generator circuit operates from a ground potential (0 V) and produces positive pulses using two 1.7 kV MOSFETs in a push-pull arrangement in order to achieve a fast turn-on / turn off rate of around 900V / 50 ns.

[0180] The pulse generator circuit may output an electroporation waveform for delivery along the auxiliary transmission line to the microelectrode array.

[0181] The electroporation waveform may have a pulse width in the range from 1 ns to 10 ms, although the invention need not be limited to this range. Shorter duration pulses (e.g. equal to or less than 10 ns) may be preferred for reversible electroporation. Preferably the rise time of each pulse is equal to or less than 90% of the pulse duration, more preferably equal to or less than 50% of the pulse duration, and most preferably equal to or less than 10% of the pulse duration. For the shorter pulses, the rise time may be of the order of 100 ps.

[0182] The electroporation waveform may have a pulse amplitude in the range of 10 V to 10 kV, although the invention need not be limited to this range. With this arrangement, the instrument may be able to provide an electric field amplitude of up to 2 kV / cm (20 kV / mm) between the oppositely poled electrode element pairs.

[0183] The electroporation waveform may be a single pulse or a plurality of pulses, e.g. a period train of pulses. The waveform may have a duty cycle equal to or less than 50%, e.g. in the range 0.5% to 50%.

[0184] As mentioned above, the waveform can be sinusoidal or discrete (e.g. square wave or the like). The pulses may be positive pulses from a ground potential, or a sequence of alternating positive and negative pulses from a ground potential.

[0185] The electroporation energy may be delivered during a treatment period that is selected depending on the desired effect. For example, the treatment period may be short, e.g. less than 1 second, or a few seconds, or around 1 minute. Alternatively the treatment period may be longer, e.g. up to an hour. 008582645

[0186] 20

[0187] For irreversible electroporation, longer duration pulses or more pulses may be used relative to reversible electroporation. For example, pulse widths of the order of 200 ms delivered in a series of 10 to 100 pulses may be used for irreversible electroporation. In one example, the electroporation waveform may comprise 10x300 ps pulses of amplitude 100V / cm - 500V / cm - 1.5 kV / cm (150 V / mm) delivered three times with around 1 minute between delivery. This waveform can cause cell apoptosis or death in hepatocellular carcinoma.

[0188] The pulse generator circuit may be controllable to adapt or vary the electroporation waveform to suit the desired treatment. Thus, any of the duty cycle, pulse width and pulse amplitude may be adjustably variable.

[0189] The instrument disclosed herein may be suitable for delivering a combination of RF energy and energy for electroporation to a variety of different treatment sites. For example, the instrument may be used to treat tumours in the lung, gastrointestinal tract, brain, pancreas, and the like. The electroporation energy may be suitable for cell neutralization of glioblastoma and medulloblastoma.

[0190] The ability to perform irreversible electroporation may provide the instrument with a tissue treatment modality that is focussed at the distal tip. This may in turn permit the RF ablation modality to be used to treat a larger volume around the distal tip. In combination, the instrument can be controlled to select the volume of tissue to which energy is delivered.

[0191] In another example, the microelectrode array may be incorporated into an existing needle-based instrument used for endoscopic retrograde cholangio-pancreatography (ERCP). In this example, the microelectrode array may comprise a single electrode pair or an array of very small diameter electrodes incorporated into the needle to enable irreversible electroporation to be used as means for killing cancer cells.

[0192] The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

[0193] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

[0194] For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

[0195] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0196] Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be 008582645

[0197] 21 understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0198] It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example + / - 10%.

Claims

00858264522Claims:

1. An electrosurgical instrument for electroporation of a biological tissue, the electrosurgical instrument comprising: a transmission line for conveying electromagnetic energy having an electroporation waveform; a radiating tip electrically connected to the transmission line so as to receive the electroporation waveform from the transmission line to thereby generate an electric field across the biological tissue for electroporation of the biological tissue, the radiating tip comprising one or more electrode pairs, each electrode pair comprising: a first electrode; and a second electrode, wherein the first electrode and the second electrode define a cavity therebetween for receiving the biological tissue.

2. The electrosurgical instrument claimed in claim 1 , wherein the electrosurgical instrument further comprises a protective sheath for housing the transmission line, and wherein the instrument is moveable between: a retracted configuration where a radiating portion of the one or more electrode pairs is housed within the protective sheath to prevent the radiating portion of the one or more electrode pairs from contacting the biological tissue; and a deployed configuration where the radiating portion of the one or more electrode pairs is deployed outside the protective sheath from a distal end of the protective sheath to form the cavity for receiving the biological tissue between the first electrode and the second electrode.

3. The electrosurgical instrument claimed in claim 2, wherein the radiating tip is further moveable to a partially retracted position from the deployed position to bring the first and second electrodes together to define a smaller cavity between the first and second electrodes.

4. The electrosurgical instrument claimed in any of claims 2 to 3, wherein the first and second electrodes are formed of a shape-memory material, and wherein the first and second electrodes adopt a predetermined geometry in the deployed configuration and deform from the predetermined geometry when moving from the deployed configuration to the retracted configuration.

5. The electrosurgical instrument claimed in claim 4, wherein the predetermined geometry is substantially pincer shaped.

6. The electrosurgical instrument claimed in any of claims 2 to 5, wherein the electrosurgical instrument further comprises an insert provided at a distal end portion of the sheath, and wherein the insert comprises one or more channel pairs, each channel pair comprising: a first channel for slidably receiving the first electrode; and a second channel for slidably receiving the second electrode.008582645237. The electrosurgical instrument claimed in claim 6, wherein the first channel and the second channel are angled with respect to a longitudinal axis of the sheath such that the first and second channels diverge from the longitudinal axis towards the distal end of the sheath and converge towards the longitudinal axis towards a proximal end of the sheath.

8. The electrosurgical instrument claimed in any of claims 2 to 7, wherein the electrosurgical instrument further comprises a control mechanism adapted to move the instrument between the retracted and deployed configurations in response to a user actuation.

9. The electrosurgical instrument claimed in claim 8, wherein the instrument comprises a motor adapted to move the instrument between the retracted and deployed configurations in response to the user actuation.

10. The electrosurgical instrument claimed in claim 9, when dependent on claim 3, wherein, in response to a user actuation when the instrument is in the retracted configuration, the motor is adapted to move the electrosurgical instrument from the retracted configuration to the deployed configuration in a first movement and then move the electrosurgical instrument from the deployed configuration to the partially retracted configuration in a second movement.

11. The electrosurgical instrument claimed in claim 10, wherein, in response to a user actuation when the instrument is in the partially retracted configuration, the motor is adapted to move the electrosurgical instrument from the partially retracted configuration to the deployed configuration in a first movement and then move the electrosurgical instrument from the deployed configuration to the retracted configuration in a second movement.

12. The electrosurgical instrument claimed in any of claims 2 to 11 , wherein the electrosurgical instrument further comprises a switch adapted to prevent electromagnetic energy being conveyed to the radiating tip when the radiating tip is in the retracted configuration.

13. The electrosurgical instrument claimed in any preceding claim, wherein the radiating tip comprises one or more insulating sleeves, wherein each of the one or more insulating sleeves is provided around a respective electrode of the electrode pairs, and wherein each of the one or more insulating sleeves extends along a proximal portion of the respective electrode leaving a distal portion of the respective electrode exposed to contact the biological tissue.

14. The electrosurgical instrument claimed in any preceding claim, wherein the radiating tip comprises a plurality of electrode pairs, and optionally wherein the radiating tip comprises four electrode pairs.

15. The electrosurgical instrument claimed in any of claims 14 to 15, when dependent on claim 2, wherein each electrode pair is moveable between the deployed configuration and the retracted00858264524 configuration independently.

16. The electrosurgical instrument claimed in any preceding claim, wherein the first electrode comprises: a plurality of first elongate conductors; and one or more first cross connectors coupled between adjacent first elongate conductors, and wherein the second electrode comprises: a plurality of second elongate conductors; and one or more second cross connectors coupled between adjacent second elongate conductors.

17. The electrosurgical instrument claimed in any preceding claim, wherein the first electrode and the second electrode each comprise a pointed distal end.

18. An electrosurgical apparatus for delivering electromagnetic energy to biological tissue at a treatment site, the apparatus comprising: an electrosurgical generator arranged to output a first electroporation waveform; an electrosurgical instrument according to any preceding claim connected to the electrosurgical generator so as to receive the first electroporation waveform and generate the electric field across the biological tissue, wherein the transmission line is arranged to convey the first electroporation waveform.

19. The electrosurgical apparatus claimed in claim 18, wherein the electrosurgical generator comprises a pulse generator circuit for generating the first electroporation waveform.

20. The electrosurgical apparatus claimed in claim 19, wherein the pulse generator circuit comprises one or more rapid switching elements capable of switching ON / OFF a source voltage at the desired frequency.

21. The electrosurgical apparatus claimed in any one of claims 18 to 20, wherein the first electroporation waveform has any one or more of: a pulse width in the range from 1 ns to 10 ms, a pulse amplitude in the range of 10 V to 10 kV, and a duty cycle equal to or less than 50%.

22. The electrosurgical apparatus claimed in any one of claims 18 to 21 , wherein the electrosurgical generator is arranged to output a second signal comprising radiofrequency electromagnetic energy for coagulating or ablating the biological tissue, and wherein the transmission line is arranged to convey the second signal to the radiating tip.

23. The electrosurgical apparatus claimed in claim 22, wherein the electrosurgical generator comprises a controller adapted to: monitor an electrical characteristic of the second signal;00858264525 infer a distance between the first and second electrodes based on the electrical characteristic; and generate a control signal to cause the electrosurgical generator to adjust the first electroporation waveform based on the inferred distance between the first and second electrodes.

24. The electrosurgical apparatus claimed in any one of claims 18 to 23, when dependent on claim 2, wherein the electrosurgical generator comprises a switch adapted to prevent electromagnetic energy being conveyed to the radiating tip when the radiating tip is in the retracted configuration.

25. An electrosurgical apparatus according to any one of claims 18 to 24 further comprising a surgical scoping device, wherein the radiating tip and the transmission line are dimensioned to be insertable into an instrument channel of the surgical scoping device.

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