Mechanical–electric dual characteristics solid–liquid interfacing sensor for accurate liquid identification
Lingjie Xie, Bohan Lu, Zhengdi Sima, Yina Liu, Haifeng Ji, Zhenqiu Gao, Peng Jiang, Harm van Zalinge, Ivona Z. Mitrović, Xuhui Sun, Zhen Wen
Abstract
The demand for portable and rapid identification of liquids has challenged traditional laboratory methods. Here, we propose a high-accuracy liquid identification strategy that integrates water droplet mechanics and solid-liquid interface contact electrification. By applying non-Hookean mechanical properties of droplets, we fabricate a lotus leaf-inspired ZnO-Polydimethylsiloxane (PDMS) superhydrophobic solid-liquid sensor. Based on the special mechanical-electric coupling interface, it achieves the highest droplet pressure sensitivity of 281 mV/Pa. We have made a breakthrough in detecting diverse solution composition with a high monitoring resolution of 5 nM metal ions and 0.1% of alcohol concentration. Through the design of double-stacked devices, triboelectric signals are able to be decoupled into mechanical and contact electrification dual-mode signals. With the integration of a gated recurrent unit (GRU) model, intelligent identification of ten liquids has reached an ultrahigh accuracy of 99%, opening up a pathway for portable liquid monitoring.