Organic ionic fluid-based wearable sensors for healthcare

Wearable sensors for healthcare, as an offshoot of prospective medical devices, have been invested in with a great deal of expectations and efforts. Encouragingly, the past decades have witnessed an increased number of flexible sensing materials and some satisfactory milestones have been achieved. Among the explosive emergence of flexible materials, organic ionic fluids rank as a new dazzling star and have been widely applied in wearable sensors for healthcare due to their attractive merits, particularly their high flexibility, wide electrochemical window, design diversity, negligible saturated vapor pressure and excellent solubility. This review article systematically summarizes the categories of organic ionic fluids and the fabrication strategies of electrical sensors based on them. At the same time, the roles that organic ionic fluids play in sensors for healthcare are also interpreted in detail from the aspect of their operating principles. More importantly, combined with specific disease models, the advances and accessibility of these sensors towards various healthcare objects have been fully summarized, including body temperature, human movement, the respiratory system, the cardiovascular system and biomarkers in sweat. Finally, constructive perspectives are put forward for the future development of this exciting field.