High-Resolution Printed Ethylene Vinyl Acetate Based Strain Sensor for Impact Sensing

The strongly growing interest in digitalizing society requires simple and reliable strain-sensing concepts. In this work, a highly sensitive stretchable sensor is presented using a straightforward and scalable printing method. The piezoresistive sensor consists of conductive core–shell microspheres embedded in an elastomer. As the elastomer, ethylene vinyl acetate (EVA) is employed as an efficient and cost-effective alternative compared to polydimethylsiloxane (PDMS). EVA allows for a significantly lower percolation threshold and low hysteresis compared with PDMS. Using 35 µm microspheres, a detection limit of 0.01% is achieved. When using 4 µm microspheres, the sensor shows a detection limit of 0.015% and electromechanical robustness against 1000 cycles of 0–1% strain. The stretchable strain sensor is successfully implemented as an impact sensor and a diaphragm expansion monitoring sensor. Fast (20 ms) and high-resolution response as well as mechanical robustness to strain values greater than the linear working range of the sensor are demonstrated. The results of this research indicate the promising potential of employing conductive microspheres embedded in the EVA matrix for fast and precise strain detection applications.