Calixto Sergio, Piazza Valeria, Marañon-Ruiz Virginia Francisca
Centro de Investigaciones en Óptica, Loma del Bosque 115, Leon C.P. 37150, Gto., Mexico.
Laboratorio de Ciencias Químicas/Área de Química Orgánica, Departamento de Ciencias de la Tierra y de la Vida, Universidad de Guadalajara, Centro Universitario de los Lagos, Enrique Diaz de León 1144, Col. Paseo de la Montaña, Lagos de Moreno C.P. 47460, Jalisco, Mexico.
Materials (Basel). 2019 Jan 21;12(2):327. doi: 10.3390/ma12020327.
The use of electronic devices to measure Relative Humidity (RH) is widespread. However, under certain circumstances, for example when explosive gases are present, a spark-free method should be used. Here we suggest the use of stimuli-responsive materials, like gelatin and interpenetrated polymers, to detect RH with an optical method. These materials are hydrophilic. When water vapor is absorbed by the films the molecules attach to the films molecular network. The result is that the film thickness increases and their refractive index changes. To detect the change of these two parameters an optical method based on diffraction gratings is employed. Surface diffraction gratings are recorded on the films. Then gratings are placed in an optical configuration that is immersed in a climatic chamber. A light beam is sent to the grating where it is diffracted. Several light orders appear. Due to the absorption of water molecules the films swell and grating surface modulation changes. This implies that the diffracted orders intensity changes. A calibrating plot relating intensity as a function of RH is obtained.
使用电子设备测量相对湿度（RH）十分普遍。然而，在某些情况下，例如存在爆炸性气体时，应采用无火花方法。在此，我们建议使用刺激响应材料，如明胶和互穿聚合物，通过光学方法检测相对湿度。这些材料具有亲水性。当薄膜吸收水蒸气时，分子附着在薄膜分子网络上。结果是薄膜厚度增加且其折射率发生变化。为了检测这两个参数的变化，采用了基于衍射光栅的光学方法。在薄膜上记录表面衍射光栅。然后将光栅置于浸没在气候箱中的光学配置中。一束光束射向光栅并在那里发生衍射。出现多个光阶。由于水分子的吸收，薄膜膨胀且光栅表面调制发生变化。这意味着衍射光阶的强度发生变化。获得了将强度作为相对湿度函数的校准曲线。
