In-situ copolymerization Ion-Gel-based flexible sensor for wearable dimethyl methylphosphonate detection

Flexible electronics have been extensively investigated in recent years due to their convenient and wearable properties. Considering the practical applications in the external environment, the demand for portable and miniaturized sensing systems is prominent, for example, detecting harmful and toxic gases. Flexible sensors provide a potential novel solution for achieving the above goals, which is wearable sensing. In this paper, we develop a flexible sensor based on the ionic gel (Ion-Gel) for the detection of dimethyl methylphosphonate (DMMP). DMMP is a kind of organophosphorus gas, which may cause pollution to the environment and harm to biology. The Ion-Gel sensitive film is prepared through in-situ copolymerization of the polymer monomer poly(ethylene glycol) diacrylate (PEGDA), ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM-TFSI) and gas-sensing group hexafluoroisopropyl alcohol (HFIPA) under 365 nm ultraviolet light. The sensitive film can be patterned through a shadow mask on the interdigital electrodes ultimately. The sensor exhibits good sensitivity to the DMMP, with a lower limit of detection reaching 100 ppb under room temperature. Noteworthily, the sensor's detecting upper limit is successfully extended to high gas concentrations at 800 ppm and maintains good linearity. A flexible print board circuit (FPCB) front-end is developed for the flexible DMMP sensor to construct a wearable platform that can be attached to the hand to achieve real-time detection. When the alarm threshold is set to 2 ppm DMMP, the proposed wearable detection platform can successfully give an alarm signal within 15 s