Highly sensitive and selective multidimensional resistive strain sensors based on a stiffness-variant stretchable substrate

Highly stretchable strain sensors that are capable of collecting complex multi-axial, multidimensional strain information in real time are crucial in practical applications for human motion detection. Here we present a highly sensitive and selective multidimensional resistive strain sensor based on a monolithic integration of a stiffness-variant stretchable substrate and sensing film comprising a cross-shaped silver nanowire percolation network in a single device. The multidimensional strain sensor efficiently distinguishes strains in various directions with a large gauge factor (GF) of >20 and a wide strain-detectable range of up to 60%. The sensor also features a maximum difference in GF between the x- and y-axes of >20 and long-term performance stability for up to 500 strain cycles. The practicality of the sensor as a human motion detector is demonstrated by attaching it directly to a part of the human body and measuring the multidimensional strains that occur during motions in real time.