Transparent, Stretchable, and Adherable Ionogel with\nHigh Electrical Conductivity for Flexible Strain Sensors

Ionogels\nhave attracted considerable attention for application\nin flexible electronics. However, it is still challenging to prepare\nmultifunctional ionogels with high transparency, stretchability, adhesion\nproperties, and electrical conductivity by simple processes. Therefore,\nwe report a one-step process for the preparation of a multifunctional\nionogel, in which the polymer monomers acrylamide and hydroxyethyl\nmethacrylate are dissolved in 1-ethyl-3-methyl­imidazolium chloride,\nand then the multifunctional ionogels were prepared by a photoinitiated\ncopolymerization. Based on the good compatibility between ionic liquid\nand polymer monomer, as well as the hydrogen bonding and ion–ion\ninteraction in the gel network, the obtained ionogels exhibited high\ntransparency (>95%), elongation at break (>410%), adhesion properties\n(744 kPa, with glass as the substrate), and electrical conductivity\n(3.39 × 10<sup>–4</sup> S/cm). In addition, the strain\nsensor prepared with ionogels can be used to monitor human joint\nmotion. This work provides a simple way to prepare multifunctional\nionogels for flexible strain sensors.