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

## TL;DR

A sustainable, elastic biocarbon aerogel made from crab shells can sense both pressure and temperature changes, offering a versatile material for smart electronics.

## Contribution

A single-component biocarbon aerogel with reversibly tunable electrical and thermal conductivities for dual-mode sensing is developed from sustainable resources.

## Key findings

- The aerogel has a low through-plane thermal conductivity of 0.031 W m–1 K–1 in its uncompressed state.
- It enables temperature-invariant pressure sensing with a sensitivity of up to 36.8 kPa–1 at 100 °C.
- Switching between compressed and uncompressed states alters temperature sensitivity due to changes in thermal conductivity.

## Abstract

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.