A flexible dual-mode sensor with decoupled strain and temperature sensing for smart robots

Flexible dual mode strain-temperature sensors that mimic human skin functions are highly desired for wearable devices and intelligent robots. However, integrating dual sensing characteristics into a single sensor for simultaneous and decoupled strain-temperature detection still remains a challenge. Herein, we report a flexible dual-modal sensor that uses a "neutral surface" structural design technique to integrate an independently prepared temperature sensing layer (TSL) and strain sensing layer (SSL), for simultaneous monitoring of strain and temperature, in a decoupled manner. The TSL consists of a PDMS/BaTiO₃ based dielectric layer whose dielectric constant and thickness change in response to temperature fluctuations. The SSL consists of a resistive type Ni₈₀Cr₂₀ film whose resistance changes in response to external strain. After optimizing the temperature and strain sensing characteristics of the TSL and SSL, the obtained dual-modal flexible sensor has shown a broad temperature sensing range (30 to 200 °C), with high temperature sensitivity (-160.90 fF °C^-1), excellent linearity (0.998), and highly discernible temperature resolution (0.1 °C). Additionally, the sensor has also exhibited a wide strain monitoring range (20 to 1000 με), good strain resolution (20 με or 0.002%), and a fast strain response time (54 ms). When practically demonstrated, our sensor has successfully shown independent perception of strain and temperature, which highlights its promising application potential in the fields of smart robotics and intelligent prosthetics.