IEEE Trans Ultrason Ferroelectr Freq Control. 2021 Apr;68(4):1458-1461. doi: 10.1109/TUFFC.2020.3030636. Epub 2021 Mar 26.
Quartz crystal microbalance (QCM) has been widely used in various fields. The mass sensitivity of QCM that means the ratio between the resonant frequency shift and the mass change on the surface of the crystal wafer is a significant parameter. The accuracy of the mass sensitivity value can greatly affect the data analysis, which in turn affects the repeatability of the QCM-related experiment. Meanwhile, we noticed that most companies that provide QCMs do not give out specific electrode thickness values but a wide range of 400-10 000Å. In this letter, we quantitatively studied the effect of electrode thickness on mass sensitivity of QCM through theoretical calculation and experiment. The result shows the mass sensitivity of QCM with 10 000-Å thickness is 1.46 times and 2.08 times that of 1000- and 400-Å thickness, respectively. Obviously, the uncertainty in electrode thickness values provided by companies inevitably brings large experimental errors, which lead to inaccuracy and poor repeatability of QCM experiment. Therefore, we suggest that the companies providing QCMs should give the specific value of the electrode thickness, and then the researchers should also consider the influence of the electrode thickness when analyzing the data to improve the accuracy and repeatability.
石英晶体微天平（QCM）已被广泛应用于各个领域。QCM 的质量灵敏度是指晶体片表面的共振频率位移与质量变化之间的比值，是一个重要参数。质量灵敏度值的准确性会极大地影响数据分析，进而影响 QCM 相关实验的可重复性。同时，我们注意到，大多数提供 QCM 的公司并未给出具体的电极厚度值，而是给出了 400-10000Å 的较宽范围。在这封信中，我们通过理论计算和实验定量研究了电极厚度对 QCM 质量灵敏度的影响。结果表明，厚度为 10000Å 的 QCM 的质量灵敏度分别是厚度为 1000Å 和 400Å 的 QCM 的 1.46 倍和 2.08 倍。显然，公司提供的电极厚度值的不确定性不可避免地会带来较大的实验误差，从而导致 QCM 实验的结果不准确和可重复性差。因此，我们建议提供 QCM 的公司应给出电极厚度的具体值，而研究人员在分析数据时也应考虑电极厚度的影响，以提高准确性和可重复性。
