A low-cost, printable, and stretchable strain sensor based on highly conductive elastic composites with tunable sensitivity for human motion monitoring

Abstract

Strain sensors with high stretchability, broad strain range, high sensitivity, and good reliability are desirable, owing to their promising applications in electronic skins and human motion monitoring systems. In this paper, we report a high-performance strain sensor based on printable and stretchable electrically conductive elastic composites. This strain sensor is fabricated by mixing silver-coated polystyrene spheres (PS@Ag) and liquid polydimethylsiloxane (PDMS) and screen-printed to a desirable geometry. The strain sensor exhibits fascinating comprehensive performances, including high electrical conductivity (1.65 × 104 S/m), large workable strain range (> 80%), high sensitivity (gauge factor of 17.5 in strain of 0%–10%, 6.0 in strain of 10%–60% and 78.6 in strain of 60%–80%), inconspicuous resistance overshoot (< 15%), good reproducibility and excellent long-term stability (1,750 h at 85 °C/85% relative humidity) for PS@Ag/PDMS-60, which only contains ∼ 36.7 wt.% of silver. Simultaneously, this strain sensor provides the advantages of low-cost, simple, and large-area scalable fabrication, as well as robust mechanical properties and versatility in applications. Based on these performance characteristics, its applications in flexible printed electrodes and monitoring vigorous human motions are demonstrated, revealing its tremendous potential for applications in flexible and wearable electronics.