A Low‐Cost, Handheld Optical Stiffness Sensor for Minimally Invasive Surgery

Palpation is a vital diagnostic tool constrained by its reliance on clinical expertise and the lack of direct tissue access in minimally invasive surgery. To address these challenges, a novel soft miniature stiffness sensor that can simultaneously estimate both applied pressure and resulting strain in biological tissue is reported. The system integrates two fiber‐optic sensing mechanisms within a unified compact structure that is just 1 cm in diameter. The compliant force sensing module, based on optical attenuation within a deformable translucent medium, is specifically designed to minimize tissue damage during force measurement, while an integrated optical reflection sensor enables precise displacement monitoring. The optical soft force sensor measures axial forces up to 5 N at a resolution of 0.027 N, while the optical displacement sensor detects displacements of up to 4 mm at a resolution of 0.04 mm. Validation on materials with Shore hardness 00‐10 to 30 A demonstrates high stiffness measurement accuracy with a mean error of 4.23%. This approach offers a reliable, cost‐effective solution for providing objective diagnostic data and enabling virtual palpation in medical applications.