[17p-Z24-1~14] 12.3 Functional Materials and Novel Devices

▼ [17p-Z24-8] A Highly Sensitive Humidity Sensor Based on AIE luminogen-appended Hygroscopic Microresonator

〇(DC)Airong Qiagedeer¹, Hiroshi Yamagishi^1,2, Minami Sakamoto³, Hanako Hasebe³, Fumitaka Ishiwari³, Takanori Fukushima³, Yohei Yamamoto^1,2 (1.Unv. of Tsukuba, 2.TREMS, 3.Tokyo Inst. of Tech)

Keywords:humidity sensing, microresonator, whispering gallery mode

Whispering gallery mode (WGM) optical resonators confine light via total internal reflection at the outermost surface of the resonator. This efficient light confinement strongly enhances light–matter interaction, especially at the periphery of the resonator. Therefore, their unique spectral feature which strongly depends on the size, geometry and refractive index of the resonator can be applied to highly sensitive chemical and physical sensing. Humidity is one of the major targets in the field of sensors because water molecules often affect the high precision manufacturing processes or chemical synthesis/purification processes. High precision and active configuration of the WGM optical humidity sensors are particularly advantageous for this purpose. However, existing active WGM humidity sensors often suffer from poor luminescence intensity and poor chemical robustness toward moisture uptake. To overcome these problems, here we newly design a hygroscopic polymer appended with aggregation-induced emission (AIE) luminogen and prove its excellent performance as a WGM humidity sensor. The newly synthesized polymer (PAA-TPE) is composed of poly(acrylic acid) and AIE luminescent branches. PAA-TPE microspheres, formed by sluggish self-assembly in solution, work as WGM resonators and exhibit peak shift when increasing or decreasing the surrounding humidity with a sensitivity as high as 255 pm/%RH, which is the highest value among the reported active optical sensors. The sensitivity toward humidity is kept intact even after several cycles of absorption and desorption of water vapor.