Institute of Electronic Sensor Systems, Graz University of Technology, 8010 Graz, Austria.
Institute of Solid State Physics, NAWI Graz, Graz University of Technology, 8010 Graz, Austria.
Sensors (Basel). 2019 Feb 26;19(5):999. doi: 10.3390/s19050999.
With the application of a recently developed deposition method called initiated chemical vapor deposition (iCVD), responsive hydrogel thin films in the order of a few hundred nanometers were created. When in contact with humid air, the hydrogel layer increases its thickness considerably. The measurement of the thickness change was realized interferometrically with a laser and a broadband light source in two different implementations. The relative change in thickness with respect to humidity can be described with the Flory⁻Huggins theory. The required Flory⁻Huggins interaction parameter was determined for the actual hydrogel composition. The setup was designed without electric components in the vicinity of the active sensor layer and is therefore applicable in harsh environments such as explosive or corrosive ones. The implemented sensor prototype delivered reproducible relative humidity ( R H ) values and the achieved response time for an abrupt change of the humidity τ 63 ≤ 2.5 s was about three times faster compared to one of the fastest commercially available sensors on the market.
采用一种新开发的沉积方法，即引发化学气相沉积（iCVD），可以制备出厚度约几百纳米的响应性水凝胶薄膜。当与潮湿空气接触时，水凝胶层的厚度会显著增加。通过两种不同的实现方式，使用激光和宽带光源进行干涉测量来实现厚度变化的测量。厚度变化相对于湿度的关系可以用 Flory-Huggins 理论来描述。对于实际的水凝胶组成，确定了所需的 Flory-Huggins 相互作用参数。该装置的设计没有在有源传感器层附近使用电子元件，因此适用于恶劣环境，如爆炸或腐蚀性环境。所实现的传感器原型能够提供可重复的相对湿度（RH）值，并且对于湿度的急剧变化，达到τ63≤2.5 s 的响应时间比市场上最快的一种商用传感器快约三倍。
