Multicore Fiber Fabry-Perot Interferometers Probe for 3-Dimensional Contact-Force (Tactile) Sensing

We propose a novel three-dimensional (3D) contact-force sensing probe that incorporates PDMS microcavities fabricated at the end face of a multicore fiber using the lift-and-pull method, forming multiple Fabry-Perot interferometers. A new method was developed to determine the cavity length by monitoring changes in the interference spectra from the Fabry-Perot cavities across different cores, enabling the accurate reconstruction of 3D contact-forces. The probe's ability to measure both the magnitude and direction of contact-force was validated through simulations and experimental tests. Additionally, the crosstalk between force magnitude and temperature is as low as 0.057 mN/°C, with the force direction measurement remaining completely immune to temperature variations. This highly compact and easily manufacturable probe shows significant potential for applications in flexible robotics and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in vivo</i> sensing.