A Force Measurement Device Using Optical Fiber for Surgical Tools - Basic Concept and Implementation -

The system proposed here measures compressive and tensile stress working longitudinally in an endoscopic surgical-assistant robot tool for the palpation of lung cancer. The force sensor is a safe, sanitary Fiber Bragg Grating (FBG) strain sensor. Such sensors are suitable for medical applications but have the disadvantage of force measurement being adversely affected by temperature. An FBG sensor on a workpiece is strained simultaneously with the workpiece to measure force based on the strain degree. A workpiece with a high Young’s modulus decrease strain, compromising sensor measurement resolution. Our proposal, discussed and evaluated in the sections that follow, solves these problems of temperature compensation and measurement resolution. The trial device we fabricated amplifies strain to enhance measurement resolution. We measured FBG sensor performance by applying compressive and tensile stress longitudinally on the trial device and determined, based on measurement results, that strain was amplified. We also confirmed that FBG sensormeasurement corresponded linearly to the compressive and tensile stress of 0-3 N. The trial device we fabricated filtered bending and torsional stress – excluding tensile and compressive stress – applied to the workpiece and confirmed device effectiveness in suppressing bending and torsional stress. Our trial device for temperature compensation solves the problems of the FBG sensor within a small, lightweight package.