Sensitivity–stability trade-off in conductive foam-based pressure sensors

Abstract

Flexible conductive foam-based pressure sensors, as a crucial component of wearable electronics, have garnered extensive attention in the fields of soft robotics and human–machine interaction due to their light weight, simple fabrication process and low cost. The majority of published studies, however, have focused on their foundational mechanical sensing properties including high sensitivity, wide detection range, etc., while ignoring the instability caused by low interfacial bonding strength between conductive fillers and foam skeleton, as well as the external environment in practical applications. Herein, through surface modification and interfacial microstructure design, a piezoresistive foam-type pressure sensor with high sensitivity and high stability is developed. The synergistic effect of the combination of surface modification and interfacial microstructure endows the sensor with great sensitivity (14.16 kPa⁻¹ for the pressure range of 0–5 kPa), a low limit of detection (∼6.3 × 10⁻⁶ kPa), and exceptional durability (over 13 000 compression/recovery cycles). Furthermore, a wireless pressure acquisition system based on a 5 × 5 piezoresistive foam-type sensor array is developed, which can accurately recognize the spatial pressure distribution of the placed objects. This work presents a straightforward approach for realizing the trade-off between sensitivity and stability of conductive foam-based sensors, paving the way for their practical applications in wearable electronics, bionic robots, and other fields.