Triboelectric nanogenerator based on well-dispersed and oxide-free liquid metal-doped conductive hydrogel as self-powered wearable sensor for respiratory and thyroid cartilage signal monitoring

The poor dispersibility and easy surface oxidation of liquid metal (LM) significantly reduce the conductivity, mechanical property and stability of the composite hydrogels, thereby affecting their sensing performance. Herein, a well-dispersed and oxide-free LM-doped conductive double network (DN) hydrogel (CMC/P(AA-coDAC)/NaCl-LM) is successfully prepared by employing bio-macromolecules (carboxymethyl cellulose (CMC) and double-bond functionalized CMC (CMC-AGE crosslinker) encapsulated oxide-free LM droplet at acidic condition as the first network and poly(acrylic acid-co-acryloyloxyethyltrimethyl ammonium chloride) (P(AA-co-DAC)) as the second network under the presence of NaCl. In this hydrogel, the multiple interactions and the synergistic effect between two interpenetrating networks insures multifunctional features of the hydrogels. As a result, the composite hydrogel exhibits superior mechanical properties (stress of 389.81 kPa and strain of 2866.44 %) and high conductivity (5.27 S/m). Subsequently, a triboelectric nanogenerator (CPL-TENG) is constructed using the composite hydrogel as electrode material, which displayed an excellent electrical out performance (V-OC of 223.32 V, I-SC of 9.78 mu A, Q(SC) of 82.33 nC, and power density of 4.30 W/m(2)) and highly-sensitive (pressure sensitivity of 0.268 kPa(-1)). Eventually, the as-fabricated CPL-TENG as a self-powered sensor for respiratory signal monitoring and machine learning-assisted language recognition is described and its great potential in wearable electronics and energy supply devices is foreseen.