Soft Transducers With Notch Filters for Spatially Distributed Strain Sensing

Sensor arrays for soft and stretchable electronics typically require a large number of electrical leads that scale with the number of sensing nodes within an array. Whereas rigid electronics can incorporate transistors and complex CMOS architectures for sensor multiplexing, soft material circuits are largely limited in how individual sensing nodes can be addressed. To overcome this challenge, we introduce an approach that utilizes a variable-frequency notch filter to encapsulate resistive or capacitive soft-material and rigid sensors for use in the detection of phenomena including material strain, applied force, and temperature. This design builds on the rich and growing body of research using capacitive and resistive soft material sensors, providing a customizable framework on which to build distributed sensing networks. In particular, we investigate how incorporating strain-sensitive components into a notch filter enables tuning of the sensor’s sensitivity, independent of the particular capacitor or resistor design, allowing sensor responses to be isolated and allow network reconfiguration without calibration. Our approach offers a straightforward means of connecting multiple sensors, even of different types, in a common sensing network with minimal wiring and interface requirements. The active filters were designed to fit in a small area and require minimal rigid components to facilitate incorporation into highly stretchable or bendable soft systems.