Traditional ionic liquids are sensitive to humidity but with long response time and nonlinear response. Pure liquid-state ionic liquids are usually hard for dehydration which have ultralong response time for humidity sensing. The immobilization of ionic liquids provide a possible way for high performance humidity sensing. Hydrophobic materials and structures also promised faster response in humidity sensing, because of easier desorption of water. In this work, we prepared flexible humidity sensitive composites based on hydrophobic ionic liquid and polymer. The combination of hydrophobic ionic liquid with hydrophobic polymer realized linear response, high sensitivity with low hysteresis to humidity. By adjusting the ratio of ionic liquid, not only the impedance but also the hydrophobicity of composite could be modulated, which had a significant influence on the humidity sensing performance. The morphology and microstructure of the material also affected its interaction with water molecules. Due to the diverse processing methods of polymer, highly transparent film fabricated by spinning-coating and nanofibrous membrane fabricated by electrospinning could be prepared and exhibited different response time, which could be used for different application scenarios. Especially, the fibrous membrane made with electrospinning method showed an ultrafast response and could distinguish up to 120 Hz humidity change, due to its fibrous structure with high specific surface area. The humidity sensors with ultrafast, linear response and high sensitivity showed potential applications in human respiratory monitoring and flexible non-contact switch. To better show the multifunction of ionic liquid-polymer composite, as a proof of concept, we fabricated an integrated humidity sensitive color change device by utilizing lower ionic liquid content composite for sensing in the humidity sensing module and higher ionic liquid content composite as the electrolyte in the electrochromic module.

传统的离子液体对湿度敏感，但响应时间长且具有非线性响应。纯液态离子液体通常难以脱水，对湿度感应的响应时间超长。离子液体的固定化为高性能的湿度感测提供了一种可能的方式。疏水性材料和结构还有望在湿度感测中具有更快的响应速度，这是因为水分易于解吸。在这项工作中，我们基于疏水性离子液体和聚合物制备了柔软的对湿度敏感的复合材料。疏水性离子液体与疏水性聚合物的结合实现了线性响应，高灵敏度和低滞后性。通过调节离子液体的比例，不仅可以调节复合材料的阻抗，而且可以调节其疏水性，这对湿度感测性能有重大影响。材料的形态和微观结构也影响了它与水分子的相互作用。由于聚合物的加工方法多样，可以制备旋涂法制备的高透明薄膜和电纺丝法制备的纳米纤维膜，并表现出不同的响应时间，可用于不同的应用场合。特别地，由于静电纺丝法制得的纤维膜具有高的比表面积，因此该纤维膜显示出超快的响应并且可以区分高达120Hz的湿度变化。具有超快，线性响应和高灵敏度的湿度传感器在人体呼吸监测和灵活的非接触式开关中显示出潜在的应用。