Piezoelectric tactile sensor for submucosal tumor detection in endoscopy

In this study, we have fabricated a miniaturized piezoelectric tactile sensor (Ø = 1.4 mm) that is suitable for mounting on an endoscope to detect submucosal tumors. The sensing mechanism is based on a tandem spring model and consists of two components with varying stiffness, namely a hard inner structure embedded in a soft outer packaging. The voltage output of the PVDF sensing film is proportional to the localized normal stress exerted by each component and this differential output can be used to extract information about the elasticity of the test object/biological tissue. The sensor design has been tested by embedding different elastomers and artificial tumors in a pig's stomach for simulating the conditions of submucosal tumors in humans and shows good agreement with theoretical analysis and numerical simulations. The sensor response is proportional to the Young's modulus of test sample over a range of 1.01-3.51 MPa, making it suitable for detection of tumors present in soft tissues. The proposed miniaturized tactile sensor utilizes a passive sensing element, is wired to the external readout system through the metal catheter which can be inserted into the endoscopic channel, is safe for insertion into the stomach as it has a biocompatible packaging and can thus be utilized to provide tactile information during regular endoscopy.