School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu611731, China.
Anal Chem. 2023 Feb 7;95(5):3075-3081. doi: 10.1021/acs.analchem.2c05239. Epub 2023 Jan 24.
Quartz crystal microbalance (QCM) operating in liquid can detect not only liquid mechanical properties (liquid density and viscosity) but also liquid electrical properties (liquid dielectric constant and conductivity). However, the relevant research so far has mainly focused on the liquid conductive property and mostly used relative values, which cannot fully reflect the response of QCM to liquid electrical properties. To study the effect of the electrical field scattering on the QCM response to liquid electrical properties and whether there is a coupling between the mechanical, dielectric, and conductive properties, reference groups for excluding the liquid mechanical effect were set up; solutions (isopropanol/water) with different dielectric constants and conductivities were adopted; static capacitance of the QCM covered with the isopropanol/water solutions was measured. The results indicate that the electrical field scattering plays an important role in the sensitivity of QCM to the dielectric property of liquid. There may be no, or very little, coupling between mechanical and electrical properties, but there is a coupling between dielectric and conductive properties at low conductivity, while at high conductivity, the conductive property is the dominant factor. The results are meaningful for understanding the multi-property sensing of QCM in the liquid phase.
石英晶体微天平（QCM）在液体中工作不仅可以检测液体的力学性质（液体密度和粘度），还可以检测液体的电学性质（液体介电常数和电导率）。然而，到目前为止，相关研究主要集中在液体的导电性质上，并且大多使用相对值，这不能充分反映 QCM 对液体电学性质的响应。为了研究电场散射对 QCM 响应液体电学性质的影响，以及机械、介电和导电性质之间是否存在耦合，设置了排除液体力学效应的参考组；采用具有不同介电常数和电导率的溶液（异丙醇/水）；测量了用异丙醇/水溶液覆盖的 QCM 的静态电容。结果表明，电场散射对 QCM 对液体介电性质的灵敏度起着重要作用。机械和电学性质之间可能没有或很少有耦合，但在低电导率下存在介电和导电性质之间的耦合，而在高电导率下，导电性质是主导因素。这些结果对于理解 QCM 在液相中的多物性传感具有重要意义。
