Simultaneously Achieving Ultrahigh Sensitivity and Wide Detection Range for Stretchable Strain Sensors with an Interface-Locking Strategy

The development of stretchable strain sensors is crucial for the implementation of electronic skins and wearable electronics. Resistive-type strain sensors are typically composed of an electrically conductive sensing layer coupled to a stretchable substrate. When a sensor is stretched, microstructural changes in the sensing layer lead to a strain-dependent change in resistance. However, strain sensors with high sensitivity and specificity often suffer from a limited detection range along with reliability issues. Here, a novel strain sensor composed of Ag particles and long-range entangled carbon nanotubes (CNTs) with a special composite design is proposed, in which a strain-induced self-locking effect is introduced at the interface between the CNT film and a percolating network consisting of Ag particle filler. As a result, the sensors achieve significantly enhanced performance such as large stretchability (>= 120%), high gauge factor (3990.8), fast response time (<33 ms), and high mechanical durability. A range of wearable applications including radial artery, facial expression, and joint motion monitoring are demonstrated, which range from minute deformation to excessive stretching of the sensor.