A low-cost piezoresistive pressure sensor with a wide strain range – featuring polyurethane sponge@poly(vinyl alcohol)/sulfuric gel electrolyte

Abstract

Piezoresistive pressure sensors based on conductive polyurethane (PU) sponge have attracted much attention due to their facile fabrication, convenient signal collection and good stability, yet it is a challenge to prepare a cost-effective PU composite for pressure sensing with good sensitivity and a wide strain range. Herein, a conductive poly(vinyl alcohol)/sulfuric gel electrolyte@PU (PVA/H₂SO₄@PU) composite is fabricated by impregnating commercial PU sponge into a PVA/H₂SO₄ gel electrolyte. The conductivity of the as-prepared composite is provided by the gel electrolyte and the carbonized PU sponge by sulfuric acid. Due to the typical porous structure of the elastic PU sponge and the high elasticity of the PVA/H₂SO₄ gel electrolyte, the composite shows excellent compression performance. The PVA/H₂SO₄@PU-based piezoresistive pressure sensor exhibits a good sensitivity of 0.080 kPa⁻¹ in a tiny and low pressure range (0.51–3.01 kPa), a wide sensing range (0–80.0%) and a long durability over 1800 s (1325 cycles). Thereafter, the pressure sensor was used to monitor facial muscle movements, airflow, finger bending, grasping different amounts of weights, etc. This indicates that the pressure sensor obtained in this work has broad application prospects in human activity monitoring. Furthermore, the PVA/H₂SO₄ gel electrolyte is readily available and inexpensive, which reduces the cost of the composites for pressure sensing.