You Borwen, Huang Chih-Feng, Lu Ja-Yu
Department of Physics, National Changhua University of Education, No. 1 Jinde Road, Changhua 500207, Taiwan.
Department of Chemical Engineering, i-Center for Advanced Science and Technology (iCAST), National Chung Hsing University, 145 Xingda Road, South District, Taichung 40227, Taiwan.
Polymers (Basel). 2023 Aug 4;15(15):3302. doi: 10.3390/polym15153302.
A simple and compact intensity-interrogated terahertz (THz) relative humidity (RH) sensing platform is successfully demonstrated in experiments on the basis of combining a porous polymer sensing membrane and a continuous THz electronic system. The RH-sensing membrane is fabricated by surface modification of a porous polymer substrate with hydrophilic and photosensitive copolymer brushes via a UV-induced graft-polymerization process. The intensity interrogation sensing scheme indicated that the power reduction of the 0.4 THz wave is dependent on the grafting density of the copolymer brushes and proportional to the RH percent levels in the humidity-controlled air-sealed chamber. This finding was verified by the water contact angle measurement. Based on the slope of the proportional relation, the best sensitivity of the hydrophilic surface-modified sensing membrane was demonstrated at 0.0423 mV/% RH at the copolymer brush density of 1.57 mg/mm grafted on the single side of the sensing membrane. The sensitivity corresponds to a detection limit of approximately 1% RH. The THz RH sensing membrane was proven to exhibit the advantages of low loss, low cost, flexibility, high sensitivity, high RH resolution, and a wide RH working range of 25-99%. Thus, it is a good candidate for novel applications of wearable electronics, water- or moisture-related industrial and bio-sensing.
在将多孔聚合物传感膜与连续太赫兹电子系统相结合的基础上，通过实验成功展示了一种简单紧凑的强度询问式太赫兹（THz）相对湿度（RH）传感平台。RH传感膜是通过紫外线诱导接枝聚合过程，用亲水性和光敏性共聚物刷对多孔聚合物基板进行表面改性制备而成。强度询问传感方案表明，0.4太赫兹波的功率降低取决于共聚物刷的接枝密度，并且与湿度控制的气密室内的RH百分比水平成正比。这一发现通过水接触角测量得到了验证。基于比例关系的斜率，在传感膜单侧接枝的共聚物刷密度为1.57 mg/mm时，亲水性表面改性传感膜的最佳灵敏度为0.0423 mV/%RH。该灵敏度对应的检测极限约为1%RH。太赫兹RH传感膜被证明具有低损耗、低成本、灵活性、高灵敏度、高RH分辨率以及25-99%的宽RH工作范围等优点。因此，它是可穿戴电子设备、与水或湿气相关的工业和生物传感等新应用的良好候选者。
