Electrosurgical instrument
In one aspect, the disclosure presents an electrosurgical instrument for performing haemostasis by radiating microwave energy from a distal tip, where conductive radiating electrodes are coated in an insulating non-stick material. In another aspect, the disclosure provides an electrosurgical instrument for performing haemostasis using radiofrequency or microwave electromagnetic energy, where a distal tip of the instrument comprises a conductive hollow needle for conveying fluid to or from a treatment site, wherein the hollow needle is electrically grounded.
1. An electrosurgical instrument comprising:
a coaxial feed cable for conveying microwave energy, the coaxial feed cable having an inner conductor, an outer conductor, and a dielectric material separating the inner conductor and the outer conductor;
an instrument tip disposed at a distal end of the coaxial feed cable to receive the microwave energy; and
a fluid channel for conveying fluid to the instrument tip,
wherein the instrument tip comprises:
a dielectric body;
a radiating structure for radiating the microwave energy into biological tissue, wherein the radiating structure is formed in or on the dielectric body, and wherein the radiating structure includes a first electrode that is electrically connected to the inner conductor, and a second electrode that is electrically connected to the outer conductor, the first electrode and the second electrode being exposed on an outer surface of the dielectric body;
a hollow needle in fluid communication with the fluid channel, the hollow needle being arranged to deliver fluid from the fluid channel to a treatment site, and
a grounding element arranged to electrically connect the hollow needle to the outer conductor;
wherein the radiating structure is coated with an insulating non-stick material.
2. An electrosurgical instrument according to claim 1 , wherein the instrument tip is coated with the insulating non-stick material.
3. An electrosurgical instrument according to claim 1 , wherein a coating of the insulating non-stick material over the radiating structure has a thickness equal to or less than 40 μm.
4. An electrosurgical instrument according to claim 3 , wherein the thickness is equal to or less than 10 μm.
5. An electrosurgical instrument according to claim 1 , wherein the insulating non-stick material is Parylene C or Parylene D.
6. An electrosurgical instrument according to claim 1 , wherein the grounding element includes a body having a first connection surface and a second connection surface arranged to retain the hollow needle and outer conductor respectively, wherein the first connection surface and the second connection surface are electrically connected together, and wherein the hollow needle is electrically connected to the first connection surface and the outer conductor is electrically connected to the second connection surface.
7. An electrosurgical instrument according to claim 6 , wherein:
the body of the grounding element has a first channel extending therethrough, the first connection surface being formed within the first channel;
a portion of the hollow needle is received in the first channel; and
the first channel includes a flared portion located at a proximal end of the first channel, the flared portion having a cross-sectional area that increases towards the proximal end of the first channel.
8. An electrosurgical instrument according to claim 7 , wherein:
the body of the grounding element includes a second channel extending therethrough, the second connection surface being formed in the second channel; and
a distal portion of the outer conductor is received in the second channel.
9. An electrosurgical instrument according to claim 6 , further comprising:
a first insulating sleeve arranged at a proximal end of the grounding element to guide the hollow needle into contact with the first connection surface, and
a second insulating sleeve arranged at a distal end of the grounding element to insulate the hollow needle from the radiating structure.
10. An electrosurgical instrument according to claim 1 , wherein the hollow needle is movable relative to the instrument tip between:
a retracted position, in which a distal end of the hollow needle is set back from a distal end of instrument tip; and
an exposed position, in which the distal end of the hollow needle protrudes beyond the distal end of the instrument tip.
11. An electrosurgical instrument according to claim 10 , wherein the hollow needle is slidable relative to the outer conductor, and the electrical connection between the hollow needle and outer conductor passes across a sliding interface.
12. An electrosurgical instrument according to claim 10 , wherein the instrument tip includes an opening at the distal end thereof, and wherein:
when the hollow needle is in the retracted position, the distal end of the hollow needle is located in the instrument tip and does not protrude through the opening;
when the hollow needle is in the exposed position, the distal end of the hollow needle protrudes through the opening.
13. An electrosurgical instrument according to claim 10 , wherein, when in the exposed position, the hollow needle is electrically connected to the outer conductor via the grounding element at a position on the hollow needle that corresponds to an integer number of half wavelengths of the microwave energy away from the distal end of the hollow needle.
14. An electrosurgical instrument according to claim 1 , wherein the dielectric body includes a first groove in which the first electrode is disposed and a second groove in which the second electrode is disposed.
15. An electrosurgical instrument according to claim 1 , wherein the dielectric body is a cylinder having a longitudinal axis aligned with the coaxial cable, and wherein the dielectric body comprises a longitudinally extending channel formed therein, and a portion of the hollow needle is received in the longitudinally extending channel.
16. An electrosurgical instrument according to claim 15 , wherein the first electrode includes a first set of longitudinally extending conductive fingers disposed around a circumference of the dielectric body.
17. An electrosurgical instrument according to claim 16 , wherein the second electrode includes a second set of longitudinally extending conductive fingers disposed around the circumference of the dielectric body, and wherein the first set and second set of conductive fingers are arranged in an interdigitated manner around the circumference of the dielectric body.
18. An electrosurgical instrument according to claim 1 , wherein the instrument tip further comprises a shielding conductor electrically connected to the outer conductor and enclosing an electrical connection between the coaxial feed cable and the radiating structure.
19. An electrosurgical instrument according to claim 1 , wherein a distal end of the instrument tip is shaped in a smoothly contoured manner to be suitable for applying a pressure spot to a target area.
20. An electrosurgical system for treating biological tissue, the system comprising:
an electrosurgical generator arranged to supply microwave energy or radiofrequency energy; and
an electrosurgical instrument according to claim 1 connected to receive the microwave energy or radiofrequency energy from the electrosurgical generator.
21. An electrosurgical system according to claim 20 further comprising a surgical scoping device having a flexible insertion cord for insertion into a patient's body, wherein the flexible insertion cord has an instrument channel running along its length, and wherein the electrosurgical instrument is dimensioned to fit within the instrument channel.
22. An electrosurgical instrument comprising:
a coaxial feed cable for conveying microwave energy or radiofrequency energy, the coaxial feed cable having an inner conductor, an outer conductor, and a dielectric material separating the inner conductor and the outer conductor;
an instrument tip disposed at a distal end of the coaxial feed cable to receive the microwave energy or the radiofrequency energy; and
a fluid channel for conveying fluid to the instrument tip;
wherein the instrument tip comprises:
a dielectric body;
an energy delivery structure for delivering the microwave energy or the radiofrequency energy into biological tissue; and
a hollow needle in fluid communication with the fluid channel, the hollow needle being arranged to deliver fluid from the fluid channel to a treatment site,
wherein the energy delivery structure comprises a radiating structure for radiating the microwave energy received from the coaxial feed cable into biological tissue,
wherein the radiating structure is formed in or on the dielectric body, and wherein the radiating structure includes a first electrode that is electrically connected to the inner conductor, and a second electrode that is electrically connected to the outer conductor, the first electrode and the second electrode being exposed on an outer surface of the dielectric body, and
wherein the hollow needle is electrically connected to the outer conductor to ground the hollow needle.