A Flexible Capacitive Tactile Sensor Array With CMOS Readout Circuits for Pulse Diagnosis

Pulse diagnosis is one of the major methods used in traditional Chinese medicine to evaluate a patient's health conditions. Determination of pulse patterns is, however, a matter that depends on technical skill and subjective experience of a doctor. Development of a pulse diagnosis apparatus can lead to modernization and advancement of the field by providing more objective and accurate evaluations. This paper aims at demonstrating real-time pulse measurement using the developed flexible capacitive tactile sensors. A 5× 5 sensor array of 0.75 cm × 1 cm in size was implemented using flexible printed circuit boards and integrated with CMOS switched-capacitor readout circuits. The measured average output sensitivity was 1.57 mV/mmHg and minimum detectable pressure and capacitance were at the sub-mmHg and sub-fF levels, respectively. The cross sensitivity was measured to be 7.8%. Real-time pulse measurement has been successfully demonstrated using the developed flexible sensor array.