Medical device

Abstract

A medical device is described having a handle, a shaft coupled to the handle and an end effector coupled to the shaft. In one embodiment, the device includes an ultrasonic transducer and is arranged so that ultrasonic or electrical energy can be delivered to a vessel or tissue to be treated. Various novel sensing circuits are described to allow a measure of the drive signal to be measured and fed back to a controller. An active fuse circuit is also described for protecting one or more batteries of the device from an over-current situation.

1 .- 22 . (canceled) 
     
     
         23 . A medical device comprising:
 an end effector for gripping a vessel/tissue;   one or more batteries for providing a DC voltage supply;   a signal generator coupled to the one or more batteries for generating a cyclically varying drive signal from the DC voltage supply for driving energy into the vessel/tissue;   a controller operable to control the signal generator to control the energy delivered to the vessel/tissue; and   an active fuse circuit coupled between the one or more batteries and the signal generator for protecting the one or more batteries.   
     
     
         24 . A device according to  claim 23 , wherein the active fuse circuit comprises a switch that is electrically coupled between a terminal of the one or more batteries and the signal generator; and control circuitry configured to switch the switch. 
     
     
         25 . A device according to  claim 24 , wherein the switch is arranged to disconnect the signal generator from the one or more batteries or is arranged to connect a large impedance between the signal generator and the one or more batteries. 
     
     
         26 . A device according to  claim 24 , wherein the control circuitry of the active fuse comprises circuitry for sensing a measure of the current being drawn from the one or more batteries and is configured to switch the switch in the event that the current measure exceeds a threshold. 
     
     
         27 . A device according to  claim 26 , wherein the control circuitry of the active fuse comprises a comparator for comparing the current measure with the threshold and wherein an output of the comparator controls the opening and closing of the switch. 
     
     
         28 .- 39 . (canceled)