Comparative investigation of different measurement techniques for estimating the electrical capacitance demonstrated using a DE-based smart glove

Dielectric elastomer transducers (DE transducers) have been investigated for years and are constantly being developed. The advantages of DE-based sensor are the high achievable strains, the compatibility with the human movement and the potential simultaneous use as an additional actuator. A DE transducer has a comparatively small capacitance with a relevant internal series resistance due to the conductivity of the electrodes. The research challenge is to precisely determine this capacitance with a sufficient sampling rate in order to allow also sequential evolution of several sensors. Various techniques are used to evaluate a capacitance in general, such as the evaluation via the phase shift, the charging and discharging time, or more advanced the so-called capacitance-to-digital converters. The aim of this contribution is to examine these various techniques regarding their practical suitability for evaluating DE-based sensors. The methods will be implemented and validated using a microcontroller-based circuit board. Finally, a smart DE glove will be used to demonstrate the operation of the developed electronics using multiple sensors detecting the motion of a human hand.