Design and testing of a capacitive interface for underwater stretch sensors

The growing popularity of wearable electronics has seen substantial research in soft and flexible strain sensors. From athletic performance analysis to human augmentation, there is a wide range of applications being developed. An area often overlooked is the connections between a network of wearable sensors and their measurement electronics. In dry applications this is as simple as cabling between the two. In underwater environments however this becomes more complicated. Capacitive strain sensors have been used to demonstrate underwater sensor-based motion capture in both a robotic fish and smart glove for divers. Wired connections introduced failure points and eliminated the modularity of the system for potted electronics. In this paper we have demonstrated the use of a capacitive interface as a wireless method to connect wearable strain sensors across an encapsulation to electronics. This removes the need to have wires permanently protruding through the encapsulation. The interfaces' impact on strain sensor sensitivity and measurement method has been investigated for both resistive and capacitive-based strain sensing.