Piezoelectric cantilevers promise broad prospects for gas sensing and biosensing due to the high sensitivity and fast response. The strong correlation between the resonant frequency and sensitivity leads to numerous cantilever-based sensors using the high-order flexural mode to realize higher absolute sensitivity. However, experiment results show that the relative sensitivity of the sensors decreases with the increase of the mode order. Herein, we explain the relative sensitivity degeneration of normal cantilevers with a modified coefficient of equivalent mass, and propose a cantilever-based humidity sensor using high-frequency mode driven by interdigital electrodes (IDEs) to enhance the relative sensitivity. Compared with the high-order mode excited by normal configuration (70.4 MHz), the high-frequency mode driven by IDEs (77.3 MHz) demonstrates an improved sensitivity around 39.2 Hz $\cdot $ cm2/ng (1.68x) at 10%–90% relative humidity. The sensitivity enhancement by IDEs is consistent with the result calculated by the modified coefficient. [2020-0055]

中文翻译：

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JMEMS 字母修改等效质量系数来解释压电悬臂式湿度传感器在高模式下的相对灵敏度降低

由于高灵敏度和快速响应，压电悬臂梁在气体传感和生物传感方面具有广阔的前景。谐振频率和灵敏度之间的强相关性导致许多基于悬臂的传感器使用高阶弯曲模式来实现更高的绝对灵敏度。然而，实验结果表明，传感器的相对灵敏度随着模式阶数的增加而降低。在此，我们用修正的等效质量系数解释了普通悬臂梁的相对灵敏度退化，并提出了一种基于悬臂梁的湿度传感器，该传感器使用由叉指电极 (IDE) 驱动的高频模式来提高相对灵敏度。与正常配置激发的高阶模式（70.4 MHz）相比，IDE驱动的高频模式（77. 3 MHz) 在 10%–90% 的相对湿度下，在 39.2 Hz $\cdot $ cm2/ng (1.68x) 附近显示出更高的灵敏度。IDEs 的灵敏度增强与修正系数计算的结果一致。[2020-0055]