This paper is concerned with the development of a palpation sensor for detecting the prostatic cancer and hypertrophy. The sensor is a layered medium with two polyvinylidene fluoride (PVDF) films embedded in the matrix rubber block. The temporal mean values, I1 and I2, of absolute voltage signals from the polymer films are calculated and their ratio I1/I2 is used as the sensor output. First, the fundamental characteristics of sensor are examined on a rectangular sensor with a plane surface. Then, the surface geometry of sensor is designed so that the sensor output clearly extracts the features on the stiffness of the materials. Finally, a compact cylindrical sensor which is inset in the doctor's forefinger is presented and its characteristics as a palpation sensor are studied experimentally. Some representative clinical data on the hardened and normal prostate glands are also presented.
