A Fabry-Perot optical fiber force sensor based on intensity modulation for needle tip force sensing

The force feedback absence in minimally invasive surgeries (MIS) is a chronic problem. The main obstacle is the intensive magnetic resonance (MR) influence on traditional electronic signals. This paper proposes a miniature and MR compatible optical force sensor based on Fabry-Perot interference (FPI) principle and interferometric-intensity modulation method. The FPI sensor, with 400μm outer diameter, is embedded in the tip of a rigid puncture needle with 1.0mm inner diameter. The sensor is simulated and fabricated, followed by signal processing using Fourier and wavelet transform analysis. Calibration results at 20 °C show that the force sensing range and resolution are 0-5N and 0.1N, respectively. Silicon rubber skin phantom insertion experiments suggest that the FPI sensor could identify clearly the type of tissues during the insertion and extraction procedure.