Smirnov Andrey, Anisimkin Vladimir, Shamsutdinova Elizaveta, Signore Maria-Assunta, Francioso Luca, Zykov Kirill, Baklaushev Vladimir, Kuznetsova Iren
Kotel'nikov Institute of Radio Engineering and Electronics of RAS, Moscow 125009, Russia.
National Research Council of Italy, Institute for Microelectronics and Microsystems, 73100 Lecce, Italy.
Sensors (Basel). 2023 Aug 22;23(17):7329. doi: 10.3390/s23177329.
The acoustic waves of higher orders propagating in a layered structure consisting of a silicon plate coated with piezoelectric and/or films were used for the development of a sensor with selective sensitivity to liquid viscosity in the range of 1-1500 cP. In that range, this sensor possessed low sensitivity to liquid conductivity and temperature T in the ranges of 0-2 S/m and 0-55 °C, respectively. The amplitude responses insensitive to the temperature instead of the phase were used to provide the necessary selectivity. The sensor was based on a weak piezoactive acoustic wave of higher order. The volume of the probes sufficient for the measurements was about 100 μL. The characteristics of the sensors were optimized by varying the thicknesses of the structure layers, number of layers, wavelength, wave propagation direction, and the order of the acoustic waves. It was shown that in the case of the layered structure, it is possible to obtain practically the same selective sensitivity toward viscosity as for acoustic waves in pure ST, X quartz. The most appropriate waves for this purpose are quasi-longitudinal and Lamb waves of higher order with in-plane polarization. It was found that for various ranges of viscosity = 1-20 cP, 20-100 cP, and 100-1500 cP, the maximum sensitivity of the appropriate wave is equal to 0.26 dB/cP, 0.087 dB/cP, and 0.013 dB/cP, respectively. The sensitivity of the waves under study toward the electric conductivity of the liquid is much less than the sensitivity to liquid viscosity. These two responses become comparable only for very small < 2 cP. The waves investigated have shown no temperature responses in contact with air, but in the presence of liquid, they increase depending on liquid properties. The temperature dependence of liquid viscosity is measurable by the same sensors. The results obtained have shown the possibility of designing acoustic liquid viscosity sensors based on multilayered structures. The set of possible acoustic waves in layered structures possesses modified propagation characteristics (various polarization, phase velocities, electromechanical coupling coefficients, and attenuations). It allows choosing an optimal acoustic wave to detect liquid viscosity only.
在由涂有压电薄膜和/或其他薄膜的硅板组成的分层结构中传播的高阶声波，被用于开发一种对1 - 1500厘泊范围内的液体粘度具有选择性灵敏度的传感器。在该范围内，该传感器对分别在0 - 2 S/m和0 - 55°C范围内的液体电导率和温度T具有低灵敏度。使用对温度不敏感而非对相位不敏感的幅度响应来提供必要的选择性。该传感器基于高阶弱压电活性声波。用于测量的探头体积约为100μL。通过改变结构层的厚度、层数、波长、波传播方向和声波阶数来优化传感器的特性。结果表明，对于分层结构，实际上可以获得与纯ST、X石英中的声波对粘度几乎相同的选择性灵敏度。为此目的最合适的波是具有面内极化的高阶准纵向波和兰姆波。发现对于1 - 20厘泊、20 - 100厘泊和100 - 1500厘泊的不同粘度范围，合适波的最大灵敏度分别等于0.26 dB/厘泊、0.087 dB/厘泊和0.013 dB/厘泊。所研究的波对液体电导率灵敏度远小于对液体粘度的灵敏度。仅在非常小的粘度（<2厘泊）时，这两种响应才变得可比。所研究的波在与空气接触时未显示出温度响应，但在有液体存在时，它们会根据液体性质而增加。相同的传感器可测量液体粘度的温度依赖性。所获得的结果表明了基于多层结构设计声学液体粘度传感器的可能性。分层结构中可能的声波集具有改变的传播特性（各种极化、相速度、机电耦合系数和衰减）。这允许选择仅用于检测液体粘度的最佳声波。
