An EIT-based piezoresistive sensing skin with a lattice structure

Spatially distributed sensing has gained significant value in diverse domains, with wearables as a notable application. In this work, a flexible skin-like sensor was developed for distributed pressure sensing. The sensing skin comprised a carbon black/silicone composite lattice structure embedded in a silicone sheet. The lattice-patterned structure is a distinct departure from conventional uniform sensing skins. Electrical impedance tomography (EIT) was employed to reconstruct electrical resistance over the sensing area, which was then mapped into pressure distribution based on the principle of piezoresistivity. EIT offers continuity and design simplicity as it eliminates the need for internal wiring, making it a promising technique in the wearable industry. The lattice sensing skin offered favorable sensing attributes, including quick response and recovery (75 ms and 84 ms at 85 kPa), a linear response with sensitivity as high as 0.119 kPa−1, a full-scale range of at least 100 kPa, and high repeatability (∼0.5% drop in maximum relative resistance over 300 cycles). The sensing skin was responsive over its entire area in both flat and non-planar conditions and was able to detect both single- and multi-point touch. The sensitivity and tactile area detectability varied depending on the position of applied pressure over the sensing area. Future studies will examine other lattice patterns and conductive composite fillers with the intention to develop a framework for optimizing the lattice sensing skin for tailored accuracy and resolution.