Temperature compensated strain sensing catheter

An end effector for a catheter, comprising:

• a deformable body;
• a plurality of optical fiber strain sensors operatively coupled to said deformable body;
• a temperature sensor proximate said plurality of optical fiber strain sensors for determination of the temperature of said plurality of fiber strain sensors;
• a sleeve that surrounds a portion of said deformable body, said plurality of optical fiber strain sensors and said temperature sensor being operatively coupled to said portion of said deformable body surrounded by said sleeve, said sleeve and said deformable body defining an annular gap therebetween, said sleeve including a structural member that resists radial constriction from an external pressure increase without substantially restricting bending or axial compression of said deformable body;
• and
• a thermal insulator comprising a solid material disposed in said annular gap.

A strain sensing system, comprising:

• a strain sensing assembly for an end effector of a catheter, said strain sensing assembly including a plurality of optical fiber strain sensors and a plurality of temperature sensors proximate said plurality of optical fiber strain sensors;
• an electromagnetic source operatively coupled with said plurality of optical fiber strain sensors for transmission of electromagnetic radiation to said plurality of optical fiber strain sensors;
• at least one receiver operatively coupled with said plurality of optical fiber strain sensors for reception of a returned portion of said electromagnetic radiation, said returned portion being returned by said plurality of optical fiber strain sensors;
• at least one signal conditioner operatively coupled with said plurality of temperature sensors for measurement of temperatures proximate said plurality of optical fiber strain sensors;
• a microprocessor operatively coupled with said receiver and said signal conditioner;
• and
• a digital storage device operatively coupled with said microprocessor, said digital storage device containing instructions for execution by said microprocessor, said instructions including:
• determining a plurality of apparent strains, one for each of said plurality of optical fiber sensors, said plurality of apparent strains being inferred from said returned portion of electromagnetic radiation;
• determining a plurality of thermal bias components, one for each of said plurality of apparent strains, said plurality of thermal bias components being inferred from said temperatures proximate said plurality of optical fiber strain sensors;
• and
• inferring an elastic strain for each of said plurality of optical fiber sensors based on said apparent strain and said thermal bias component of each of said plurality of optical fiber sensors.

A method for determining a force exerted on a distal end of a catheter, comprising:

• providing a strain sensing assembly including a plurality of optical fiber strain sensors and a plurality of temperature sensors proximate said plurality of optical fiber strain sensors;
• obtaining a plurality of temperature measurements, one each from said plurality of temperature sensors;
• inferring a plurality of optical fiber strain sensor temperatures, one for each of said plurality of optical fiber strain sensors, said plurality of temperatures being inferred from said plurality of temperature measurements;
• obtaining a plurality of apparent strain measurements, one for each of said plurality of optical fiber strain sensors;
• inferring a plurality of thermal bias components, one for each of said plurality of optical fiber strain sensors, said plurality of thermal bias components being inferred from said plurality of optical fiber strain sensor temperatures;
• inferring a plurality of elastic strains, one for each of said plurality of optical fiber strain sensors, from said plurality of apparent strain measurements and said plurality of thermal bias components;
• and
• determining a magnitude and a direction of said force exerted on said distal end of said catheter from said plurality of elastic strains.

A method for determining a force exerted on a distal end of a catheter, comprising:

• providing a strain sensing assembly including a trio of optical fiber strain sensors and a plurality of temperature sensors proximate said trio of optical fiber strain sensors;
• obtaining a plurality temperature measurements, one each from said plurality of temperature sensors;
• inferring a trio of optical fiber strain sensor temperatures, one for each of said trio of optical fiber strain sensors, said plurality of temperatures being inferred from said plurality of temperature measurements;
• obtaining a trio of apparent strain measurements, one for each of said trio of optical fiber strain sensors;
• steps for determining a trio of elastic strains of said from said trio of optical fiber strain sensor temperatures and said trio of apparent strain measurements, one elastic strain for each of said trio of optical fiber strain sensors;
• and
• steps for determining a magnitude and a direction of said force exerted on said distal end of said catheter from said trio of elastic strains.