Shape Sensing with Electrostatic Differential Capacitance for Ultrasound Imaging by Flexible Array Transducer

Flexible ultrasound (US) transducer, which has a potential to fit various regions of human body for diagnosis, need to have its geometry accurately measured for US image reconstruction. This paper serves a shape sensing system with the electrostatic differential capacitance for the imaging with the flexible US transducer. The shape sensing system is composed of two strips as a pair, each end of which is fixed, and focuses on the relative shift between capacitance sensors embedded in the inner and outer strips when bending the sensing system. For increasing the capacitance, we applied a silicon oil to the sensor substrate and changed the size of electrodes. Experimental results showed that the estimation error was improved by the average of 52.8% when applying the silicon oil and the average of 10.4% by increasing the size of electrodes. Additionally, US simulation was performed for investigating the influence of image reconstruction due to the sensing error. The simulation results enabled to visualize all point targets and demonstrated the feasibility that the developed sensing system are applicable for the flexible US transducer.