Ultrastretchable Polyaniline-Based Conductive Organogel with High Strain Sensitivity

Strain sensors, as a key component of wearable/stretchable electronics, typically exhibit an intrinsic conflict between large strain (>100%) and high sensitivity (gauge factor > 10). This Letter reports a solution to this trade-off by creating a high-conductivity thin layer of polyaniline (PANi) percolated through the outer surface of a polymethyl acrylate organogel. The highly robust, conductive organogel can achieve both high gauge factor and large strain via the mismatch between the fragile PANi and the elastic polyacrylate blending layer. The high gauge factor over the entire strain range of 2000% enables its broad sensing range from human pulse to massive deformation. The water-free conductive organogel provides purely electronic conductivity and allows for working under extreme conditions, which typical conductive hydrogels cannot withstand. These merits allows the sensor to present high sensitivity for both subtle movement (8% resistance change for pulse detection) and large strain (a gauge factor of 376 at 460% strain). Such a conductive organogel also demonstrated great sustainability under harsh operating conditions, as demonstrated by a dielectric elastomer actuator based on it, capable of generating a horizontal displacement of 15.7 mm (46% of the total length) at -12 degrees C, as a substitute for conventional hydrogels as the electrode.