Current leakage techniques for radio frequency instruments
Techniques for detecting leakage current of an electrosurgical instrument are provided. In an example, a method of operating an electrosurgical instrument can include applying a radio frequency (RF) signal to electrode conductors of the electrosurgical instrument, determining leakage current of an leakage conductor coupled to the electrosurgical instrument exceeds a first threshold, and providing a first indication in response to the determining the leakage current of the leakage conductor exceeds the first threshold.
1 . A system for detecting leakage current, the system comprising:
a first electrode configured for applying therapy to a patient;
a support member having a channel, the support member configured to mechanically support the first electrode;
a first electrical conductor in the form of an insulated wire coupled to the first electrode and configured to couple with an electrosurgical unit (ESU), the first electrical conductor configured to extend from the first electrode to the ESU via the channel;
a second electrical conductor in the form of an insulated wire electrically coupled to the support member, configured to detect an unintended electrical connection between the first electrical conductor and the support member; and
a leakage current detector circuit configured to receive and detect current of the second electrical conductor, to compare the detected current to a threshold value, and in response to the detected current exceeding the threshold value, to provide an indication of a leakage current condition.
2 . The system of claim 1 , wherein the leakage current detector circuit is configured to apply a test signal to the first electrode, to compare current of the second electrical conductor to a current limit in response to the test signal, and to provide the indication in response to the current of the second electrical conductor exceeding the current limit.
3 . The system of claim 1 , wherein the first electrode is coupled to a first jaw of an electrosurgical instrument, the first jaw mechanically coupled to the support member.
4 . The system of claim 1 , wherein the ESU includes the leakage current detector circuit.
5 . The system of claim 1 , including a second electrode mechanically coupled with the first electrode; and
a third electrical conductor coupled to the second electrode and configured to couple with the ESU, the third electrical conductor configured to extend from the second electrode to the ESU via the channel.
6 . The system of claim 5 , wherein the leakage current detector circuit is configured to receive the third electrical conductor, to compare current of the third electrical conductor to a second threshold value, and in response to the current of the third electrical conductor exceeding the second threshold value, to provide a second indication of a second leakage current condition.
7 . The system of claim 6 , wherein the leakage current detector circuit is configured to apply a first test signal to the first electrode, to compare current of the second electrical conductor to a current limit in response to the first test signal, and to provide the indication in response to the current of the second electrical conductor exceeding the current limit.
8 . The system of claim 7 , wherein the leakage current detector circuit is configured to apply a second test signal to the second electrode, to compare current of the second electrical conductor to the current limit in response to the second test signal, and to provide the second indication in response to the current of the second electrical conductor exceeding the current limit.
9 . The system of claim 6 , wherein the first electrode is coupled to a first jaw of an electrosurgical instrument, the first jaw mechanically coupled to the support member.
10 . The system of claim 9 , wherein the second electrode is coupled to a second jaw of the electrosurgical instrument, the second jaw mechanically coupled to the first jaw.
11 . The system of claim 1 , wherein the leakage current detector circuit includes:
a sense resistor coupled to the second electrical conductor, wherein the sense resistor is configured to receive the leakage current and generate a voltage at a node of the sense resistor, wherein the voltage at the node represents the leakage current; and
a comparator configured to receive the voltage at a node of the sense resistor, to receive a voltage representing a current limit reference, and to base the indication on a comparison of the voltage that represents the leakage current with the voltage that represents the current limit reference.
12 . The system of claim 11 , wherein the leakage current detector circuit includes a latch coupled to an output of the comparator and configured to latch the indication in response to the voltage that represents the leakage current exceeding the voltage that represents the current limit reference.