A Two-Dimensional (2D) Distributed-Deflection Sensor for Tissue Palpation With Correction Mechanism for Its Performance Variation

This paper presents a proof-of-concept study on a two-dimensional distributed-deflection sensor for tissue palpation and the associated correction mechanism for its performance variation. The core of the sensor is one whole polydimethylsiloxane microstructure embedded with a 3 × 3 sensing-plate/transducer array. Upon pressing the sensor against a tissue, the sensing-plate array translates its elasticity distribution to the deflection distribution, which registers as resistance changes by the transducer array and is further converted into the stiffness distribution. The connection of the sensing-plate/transducer array into one piece allows the sensor interacting with a tissue in a continuous manner and, thus, unifies misalignment errors from non-ideal normal contact between the sensor and the tissue. A correction mechanism is developed to remove the effect of performance variation among the sensing-plate/transducer array on the measured stiffness distribution of a tissue. The stiffness distribution normalized to the minimum stiffness across a tissue is utilized to identify the existence and location of a tumor. The related measurement errors are both theoretically and experimentally examined.