Portable pen-like device with miniaturized tactile sensor for quantitative tissue palpation in oral cancer screening

Oral cancer has consistently been ranked among the top ten cancers in terms of mortality with five year survival rates being among the lowest for all major cancers. Consequently, great efforts are being made to develop new diagnostic tools that can enable early detection in a clinical setting. In this study, we report on the design and development of a novel pen-like handheld device, with a miniaturized tactile sensor mounted on the front-end and integrated with a portable back-end readout module. The device can be used for tissue palpation in the oral cavity and obtain quantitative information regarding the elasticity of oral lesions and abnormalities, thus eliminating the need for manual palpation by the clinician. The sensing mechanism of the proposed tactile sensor is based on the two-spring model and employs two components with varying stiffness values, namely a hard copper ball embedded in a soft elastomeric packaging. The differential voltage output of the piezoelectric sensing film corresponding to the two components can provide information regarding the elasticity of the tissue under contact. To simulate feasibility of the tactile sensor in differentiating tissue elasticity, we have contacted the sensor with different elastomeric silicone materials under the same applied force. The experiments confirmed that the sensor response could be used to differentiate five silicones with varying Young’s moduli ranging from 0.2 to 3.1 MPa and a corresponding Shore hardness of 2 to 56 Shore A. A two-stage linear trend was observed with a sensitivity of 0.356/MPa for softer silicones (2 ~ 9 Shore A) and 0.059/MPa for harder silicones (24 ~ 56 Shore A). Furthermore, the portable readout module that we have developed can analyze the data from the tactile sensor and transmit it wirelessly via Bluetooth for cloud computing. The proposed device is easy-to-use in general clinical settings and could enable early detection and improved prognosis of oral cancer.