Jakubik Wiesław, Wrotniak Jarosław, Caliendo Cinzia, Benetti Massimiliano, Cannata Domenico, Notargiacomo Andrea, Stolarczyk Agnieszka, Kaźmierczak-Bałata Anna
Institute of Physics CSE, Silesian University of Technology, 44-100 Gliwice, Poland.
Institute of Electronics, Silesian University of Technology, 44-100 Gliwice, Poland.
Sensors (Basel). 2024 Jun 5;24(11):3651. doi: 10.3390/s24113651.
In the present paper the humidity sensing properties of regioregular rr-P3HT (poly-3-hexylthiophene) polymer films is investigated by means of surface acoustic wave (SAW) based sensors implemented on LiNbO (128 Y-X) and ST-quartz piezoelectric substrates. The polymeric layers were deposited along the SAW propagation path by spray coating method and the layers thickness was measured by atomic force microscopy (AFM) technique. The response of the SAW devices to relative humidity (rh) changes in the range 5-60% has been investigated by measuring the SAW phase and frequency changes induced by the (rh) absorption in the rr-P3HT layer. The SAW sensor implemented onto LiNbO showed improved performance as the thickness of the membrane increases (from 40 to 240 nm): for 240 nm thick polymeric membrane a phase shift of about -1.2 deg and -8.2 deg was measured for the fundamental (78 MHz operating frequency) and 3rd (234 MHz) harmonic wave at (rh) = 60%. A thick rr-P3HT film (600 nm) was deposited onto the quartz-based SAW sensor: the sensor showed a linear frequency shift of -20.5 Hz per unit (rh) changes in the ~5-50% rh range, and a quite fast response (5 s) even at low humidity level (5% rh). The LiNbO and quartz-based sensors response was assessed by using a dual delay line system to reduce unwanted common mode signals. The simple and cheap spray coating technology for the rr-P3HT polymer films deposition, complemented with fast low level humidity detection of the tested SAW sensors (much faster than the commercially available Michell SF-52 device), highlight their potential in a low-medium range humidity sensing application.
在本文中，通过在LiNbO(128 Y - X)和ST - 石英压电基片上实现的基于表面声波(SAW)的传感器，研究了区域规整的rr - P3HT(聚 - 3 - 己基噻吩)聚合物薄膜的湿度传感特性。聚合物层通过喷涂法沿SAW传播路径沉积，层厚度通过原子力显微镜(AFM)技术测量。通过测量rr - P3HT层中相对湿度(rh)吸收引起的SAW相位和频率变化，研究了SAW器件对5% - 60%范围内相对湿度(rh)变化的响应。在LiNbO上实现的SAW传感器随着膜厚度增加(从40 nm到240 nm)性能得到改善：对于240 nm厚的聚合物膜，在rh = 60%时，对于基波(约78 MHz工作频率)和三次谐波(约234 MHz)测量到的相移分别约为 - 1.2°和 - 8.2°。在基于石英的SAW传感器上沉积了厚约600 nm的rr - P3HT薄膜：该传感器在5% - 50% rh范围内每单位rh变化显示出约 - 20.5 Hz的线性频率偏移，即使在低湿度水平(约5% rh)下也有相当快的响应(约5 s)。通过使用双延迟线系统来减少不需要的共模信号，评估了基于LiNbO和石英的传感器的响应。用于rr - P3HT聚合物薄膜沉积的简单且廉价的喷涂技术，以及测试的SAW传感器的快速低水平湿度检测(比市售的Michell SF - 52设备快得多)，突出了它们在中低范围湿度传感应用中的潜力。
