Single-Component Elastic Biocarbon Aerogel with Reversibly Mechanotunable Electrical and Thermal Conductivities for Dual-Mode Pressure-Temperature Sensing.

Flexible dual-mode pressure-temperature sensors enable the construction of soft and smart miniature electronics and have been fabricated using assemblies with intricate structures and multiple active components derived from limited resources but are challenging to realize using a single active component derived from sustainable resources. Herein, a crab shell-derived chitin nanofiber dispersion is subjected to directional freeze-drying followed by morphology-retaining pyrolysis to afford a single-component elastic biocarbon aerogel with a high compressibility, robust elasticity, and reversibly mechanotunable pore structure and electrical and thermal conductivities. Owing to its low through-plane thermal conductivity (0.031 W m-1 K-1) in the pristine (uncompressed) state and pressure-dependent electrical conductivity, this aerogel enables temperature-invariant dynamic pressure sensing with a sensitivity of up to 36.8 kPa-1 at a unilateral heating temperature of up to 100 °C. Upon switching between compressed (80% strain) and uncompressed (0% strain) states, the temperature sensitivity of the aerogel alternates between 0.44 and 0.01 °C-1, respectively, because of the concomitant reversible change in thermal conductivity (0.031 and 0.223 W m-1 K-1, respectively). The developed aerogel provides a simple, robust, and sustainable platform for dual-mode pressure-temperature sensing in on-skin health monitoring, smart tactile electronics in soft robotics, etc.