A Flexible Strain Sensor of Ba(Ti, Nb)O₃/Mica with a Broad Working Temperature Range

Abstract Flexible strain sensors have captured a lot of attention since first being proposed. Most studies are focused on adopting new materials or developing novel structures to detect strain, temperature, and even to realize multifunction. The reliability of flexible strain sensors in harsh environments such as at low and high temperatures, however, has so far received little attention because traditional bendable or stretchable substrates, including polyethylene terephthalate, polyimide, polydimethylsiloxane, paper, silk, and cotton, cannot withstand high temperature. The poor thermostability limits their potential applications in harsh conditions such as in interstellar probes, polar exploration, petrochemical, and metal smelting. Here, a heat‐resisting flexible strain sensor is shown, consists of a BaNb_0.5Ti_0.5O₃ film on top of a 4.5 µm thick mica substrate. The device exhibits excellent thermal stability in a wide temperature range from 20 to 773.15 K. Owing to the ultrathin mica substrate and low resistance, the device demonstrates low power consumption (0.96 µW cm⁻²), is lightweight (2.06 g cm⁻³), together with having high stability over 5000 bending cycles. This work opens a path for pressure sensors applying ceramic materials that can be used from an ultralow to a high temperature.