Lazarova Katerina, Christova Darinka, Georgiev Rosen, Georgieva Biliana, Babeva Tsvetanka
Institute of Optical Materials and Technologies ''Acad. J. Malinowski'', Bulgarian Academy of Sciences, Akad. G. Bonchev str., bl. 109, 1113 Sofia, Bulgaria.
Institute of Polymers, Bulgarian Academy of Sciences, Akad. G. Bonchev Str., bl. 103-A, 1113 Sofia, Bulgaria.
Nanomaterials (Basel). 2019 Jun 10;9(6):875. doi: 10.3390/nano9060875.
Thin films with nanometer thicknesses in the range 100-400 nm are prepared from double hydrophilic copolymers of complex branched structures containing poly(-dimethyl acrylamide) and poly(ethylene oxide) blocks and are used as humidity sensitive media. Instead of using glass or opaque wafer for substrates, polymer thin films are deposited on Bragg stacks and thin (30 nm) sputtered Au-Pd films thus bringing color for the colorless polymer/glass system and enabling transmittance measurements for humidity sensing. All samples are characterized by transmittance measurements at different humidity levels in the range from 5% to 90% relative humidity. Additionally, the humidity induced color change is studied by calculating the color coordinates at different relative humidity using measured spectra of transmittance or reflectance. A special attention is paid to the selection of wavelength(s) of measurements and discriminating between different humidity levels when sensing is performed by measuring transmittance at fixed wavelengths. The influence of initial film thickness, sensor architecture, and measuring configuration on sensitivity is studied. The potential and advantages of using top covered Bragg stacks and polymer/metal thin film structures as humidity sensors with simple optical read-outs are demonstrated and discussed.
由含有聚（二甲基丙烯酰胺）和聚环氧乙烷嵌段的复杂支化结构的双亲水共聚物制备出厚度在100 - 400纳米范围内的纳米薄膜，并将其用作湿度敏感介质。聚合物薄膜不是沉积在玻璃或不透明晶圆等基底上，而是沉积在布拉格堆栈和薄（30纳米）的溅射金钯薄膜上，从而为无色聚合物/玻璃系统带来颜色，并能够进行湿度传感的透过率测量。所有样品通过在相对湿度5%至90%范围内的不同湿度水平下进行透过率测量来表征。此外，通过使用测量的透过率或反射率光谱计算不同相对湿度下的颜色坐标来研究湿度引起的颜色变化。在通过在固定波长下测量透过率进行传感时，特别关注测量波长的选择以及区分不同湿度水平。研究了初始膜厚度、传感器结构和测量配置对灵敏度的影响。展示并讨论了使用顶部覆盖布拉格堆栈和聚合物/金属薄膜结构作为具有简单光学读出的湿度传感器的潜力和优势。
