Design and response performance of capacitance meter for stretchable strain sensor

Flexible and stretchable electronics are expected to contribute to electric conductors, sensors and actuators for various applications, such as robotic systems and power-assisted systems. In this study, a stretchable strain sensor is proposed as a length sensor for a pneumatic artificial muscle. To measure the length of the artificial muscle, the stretchable strain sensor is required to have quick response characteristics. A capacitance measurement circuit based on a band-pass filter is analyzed, and is tuned by the parameters of its electric components. The circuit measures the capacitance of the strain sensor with accuracy equivalent to a commercially available LCR meter. We confirm that the combination of the capacitance meter and the strain sensor measures the length of the artificial muscle with a high sampling rate of 10 kHz.