A Tactile-Based Capsule Endoscope for Detecting Tissue Stiffness

Usage of the tactile sensing technology in biomedical applications has gradually increased to measure biomechanical properties of in-vivo and ex-vivo tissue and hence understand the relationship between the tissue stiffness and histopathological diagnosis. With this aim, we have developed a tactile sensing capsule endoscope to measure tissue's Young's Modulus, in situ. Inspired by force microscopy, the proposed capsule harbors four cantilever structures that probe the tissue surface using a single miniaturized actuator. The force applied by tissue on the cantilever tip is measured via the deformed piezoelectric layer integrated on anchor of the cantilever due to bending caused by the interaction between the tissue and the cantilever. The exerted force varies with the tissue stiffness. The tactile sensing capsule was tested on ex-vivo animal tissue, and gelatin-based tissue. According to the experimental results, the proposed tactile sensing capsule demonstrates the ability to measure the mechanical properties differences of tissue. The system can measure the Young's modulus values for ex-vivo bovine tissue as 15.135 kPa for chicken breast, 5.9 kPa for bovine liver, and 4.45 kPa and 23.65 kPa for gelatin-based samples. Overall, our proposed tactile-based capsule endoscope has a compact form and easy-to-fabricate process. Furthermore, it is localized and has the capability of quantitative Young's modulus measurements.