Circuit and Signal Processing for Capacitance Measurement of Breast Tissue

In previous studies, electrical capacitance tomography has been developed and applied for imaging breast tissue to detect abnormalities within the breast caused by simple cysts, benign tumors and malignant cancers. For accurate screening and early detection of such abnormalities, high sensitive capacitance sensor is necessary. This study proposes a novel capacitance sensor circuit and signal conditioning and processing based on capacitance–voltage circuit for breast tissue measurement. The new sensor circuit design used a biopotential capacitance electrode, capable of measuring capacitance value with a resolution as low as 0.1 fF, a sensitivity of 1.6 V/pF, and linearity of 0.98. The experiment was conducted with a hemisphere 3D sensor 24 electrodes. The experiment strategy is as follow, first the system will be calibrated using network analyzer, secondly experiment using phantom 1, and the third experiment using phantom 2. In the design, we used a reference electrode made from fixed plate to measure capacitance inside the system, which will be used further for compensation against signal fluctuation caused by environmental condition such as humidity, temperature, pressure, etc. As a result, more stable system is achieved. Based on the experiment, the system can detect abnormalities of the human breast which are represented by two phantoms with different condition.