Catheter and system for using same

A system for controlling a thin flexible thermoplastic catheter comprising:

• a plurality of shape memory alloy filaments attached to the distal end of the catheter, each filament having a solid-state phase and a temperature;
• a means for receiving a strain value for at least one of the filaments;
• a means for determining a solid-state phase change that will result in the strain value, whereby the solid-state phase change is dependent on the temperature and the temperature is dependent on a voltage;
• a means for setting the voltage in each filament thereby resulting in bending of the catheter in three dimensional space;
• a force sensor which measures forces in three degrees of freedom, the force sensor being attached to the distal end of the catheter;
• and
• a means for receiving a signal from the force sensor;
• wherein said force sensor includes:
• a two-dimensional optical position sensing detector located at a predetermined distance from the distal end of the catheter;
• a spring having a distal end and a proximal end, said distal end being attached to the detector and said proximal end being attached to the catheter whereby force on the detector moves the detector relative to the distal end of the catheter;
• a light source located at the end of the catheter coupled to an optical fibre embedded within the catheter whereby the light source emits a beam spot;
• and
• a means for determining the position of the beam spot on the detector.

A method of controlling a catheter having a plurality of shape memory alloy filaments at the distal end thereof comprising the steps of:

• receiving a strain value for at least one of the filaments;
• determining a solid state phase change that will result in the strain value, whereby the solid state phase change is dependent on the temperature and the temperature is dependent on a voltage;
• setting the voltage in each filament thereby resulting in bending of the catheter in three dimensional space;
• and
• receiving a signal from a force sensor attached to the distal end of the catheter,
• wherein said force sensor measures forces in three degrees of freedom, said force sensor comprising:
• a two-dimensional optical position sensing detector located at a predetermined distance from the distal end of the catheter;
• a spring having a distal end and a proximal end, said distal end being attached to the detector and said proximal end being attached to the catheter whereby force on the detector moves the detector relative to the distal end of the catheter;
• a light source located at the end of the catheter coupled to an optical fibre embedded within the catheter whereby the light source emits a beam spot;
• and
• a means for determining the position of the beam spot on the detector.