Breathable Foam Piezoresistive Sensor with High Sensitivity and Fast Response for Body Motion and Voice Monitoring

Foam-based piezoresistive sensors, known for their lightweight property, flexibility, and breathability, have attracted considerable attention for applications in health and motion monitoring. However, these sensors often face a critical challenge: balancing response speed and sensitivity, as higher sensitivity typically results in slower response times. In this study, we present composite foam piezoresistive sensor with three-dimensional (3D) conductive networks to address this challenge. This sensor was fabricated using thermoplastic polyurethane (TPU), carbon nanotubes (CNTs), and MXene, through a combination of salt-templating and dip-coating techniques. Experimental measurements demonstrate that this sensor achieves both high sensitivity (4.26 kPa −1) and fast response/recovery times (104/63 ms). Additionally, it offers remarkable advantages, including excellent breathability that does not cause skin irritation even after 24 h of continuous attachment, and outstanding stability with no significant performance degradation after more than 10,000 compression cycles. A stable conductive network, as well as its lightweight and flexibility, make the sensor highly suitable for real-time and long-term monitoring of diverse motion and vocal signals with minimal discomfort. The sensor's versatility is evident in smart wearable applications and demonstrated through devices for tracking body movement, gesture, and voice, it can be applied to the training of civil aviation pilots.