Flexible and Transparent Polymer-Based Optical Humidity Sensor

Thin spin-coated polymer films of amphiphilic copolymer obtained by partial acetalization of poly (vinyl alcohol) are used as humidity-sensitive media. They are deposited on polymer substrate (PET) in order to obtain a flexible humidity sensor. Pre-metallization of substrate is implemented for increasing the optical contrast of the sensor, thus improving the sensitivity. The morphology of the sensors is studied by surface profiling, while the transparency of the sensor is controlled by transmittance measurements. The sensing behavior is evaluated through monitoring of transmittance values at different levels of relative humidity gradually changing in the range 5-95% and the influence of up to 1000 bending deformations is estimated by determining the hysteresis and sensitivity of the flexible sensor after each set of deformations. The successful development of a flexible sensor for optical monitoring of humidity in a wide humidity range is demonstrated and discussed.

Automated summary

Thin spin-coated polymer films of amphiphilic copolymer obtained by partial acetalization of poly(vinyl alcohol) are used as humidity-sensitive media for flexible humidity sensor applications. Pre-metallization of the substrate is implemented to increase the optical contrast and sensitivity of the sensor. The sensing behavior is evaluated by monitoring transmittance values at different humidity levels, and the sensor's hysteresis and sensitivity are determined after bending deformations. The successful development of a flexible sensor for optical monitoring of humidity in a wide range is demonstrated and discussed.