Fiber Bragg grating-based tactile sensing tool for minimally invasive surgery

A novel miniaturized palpation probe for tactile and stiffness sensing based on fiber Bragg gratings (FBGs) is proposed in this article. The FBGs are inscribed point-by-point with femtosecond laser and integrated on a pneumatic actuated silicone membrane on the tip of the palpation probe for measuring the tactile force and the object's stiffness. During measurements, the back-reflected signals of the FBGs are monitored. The pressurecharged membrane deforms upon contact, resulting in changes to the measured FBG signal. These changes can be interpreted as the palpated force applied to the probe. Moreover, the deformation of the sensing membrane can be controlled by modulating the induced pneumatic pressure during object indentation, which results in different FBG signal responses regarding stiffness levels. Consequently, the stiffness of the object can be identified. The proposed sensor demonstrates the functionality of stiffness sensing and has the potential for integration into miniaturized tools for various minimally invasive surgical applications.