Bio-disintegrable elastic polymers for stretchable piezoresistive strain sensors

The fast-growing usage of electronics is creating large amounts of e-waste (electronic waste), most of which are directly sent into landfills or incinerated as recycling is either impractical or too costly. Therefore, it is believed that degradable, environmentally friendly materials are the solution to this pressing issue. Herein, disintegrable, durable, and highly stretchable strain sensors are developed based on elastic thin films made of sodium carboxymethyl cellulose, glycerol, and polyvinyl alcohol. The polymer thin films show a failure strain up to ≈ 330% and low hysteresis (5.74% at the second cycle) when subjected to 50% cyclic strain, due to the formation of inter or intramolecular hydrogen bonds. Carbon nanofibers with Au thin film are deposited on the elastic thin film, resulting in highly stretchable piezoresistive strain sensors with a maximum gauge factor of 1.7. More interestingly, the as-developed sensors can be completely broken down in hot water (at ≈ 95 °C) within ≈ 25 min, indicating their remarkable disintegrability. This unique characteristic is expected to contribute to environmental sustainability. The applications of the sensor for joint bending recognition as well as physiological sign measurement have been demonstrated.