Acoustic sensors for specific-frequency detection are used in various applications, and their sensitivity improvement has been attracting significant attention. Mechanical acoustic resonator technology is an effective method because of its simple structure and low power consumption. A Helmholtz resonator (HR) is a typical mechanical resonator; however, previous HRs for an acoustic sensor were attached to the rear of the sensing element, which was unsuitable for a differential pressure (DP) sensor that blocks the pressure wave propagating through the sensor chip. This paper proposes a micro-electro-mechanical system (MEMS)-based acoustic sensor, enhanced by a front-mounted parallel HR array, which is suitable for a DP sensor-type element. A piezoresistive cantilever-type DP sensor was used as the sensing element because of its high sensitivity to acoustic waves in its mechanical resonant frequency (RF) range. Its sensitivity was enhanced by attaching an HR array to the DP sensor, like a cap. We designed and fabricated a piezoresistive cantilever with dimensions 80 × 80 × 0.2 µm and an RF of 4.5 kHz, and four HR arrays with an RF close to that of the cantilever. The sensor responses to acoustic waves with and without the HRs were evaluated. The developed sensor with the HR realized three times higher sensitivity than those without the HR at the RF. The obtained acoustic pressure resolution was approximately 4 mPa.

用于特定频率检测的声学传感器被用于各种应用中，其灵敏度的提高已经引起了人们的极大关注。机械声学谐振器技术因其结构简单、功耗低而成为一种行之有效的方法。亥姆霍兹谐振器（HR）是典型的机械谐振器；但是，以前用于声学传感器的 HR 连接到传感元件的后部，这不适用于阻挡通过传感器芯片传播的压力波的差压 (DP) 传感器。本文提出了一种基于微机电系统 (MEMS) 的声学传感器，通过前置平行 HR 阵列增强，适用于 DP 传感器类型的元件。压阻式悬臂式 DP 传感器被用作传感元件，因为它在其机械共振频率 (RF) 范围内对声波具有高灵敏度。通过将 HR 阵列连接到 DP 传感器（如盖帽）来增强其灵敏度。我们设计并制造了一个尺寸为 80 × 80 × 0.2 µm 和 4.5 kHz 射频的压阻式悬臂梁，以及四个射频接近悬臂梁的 HR 阵列。评估了带有和不带有 HR 的传感器对声波的响应。开发的带有 HR 的传感器在 RF 上实现了比没有 HR 的传感器高三倍的灵敏度。获得的声压分辨率约为 4 mPa。我们设计并制造了一个尺寸为 80 × 80 × 0.2 µm 和 4.5 kHz 射频的压阻式悬臂梁，以及四个射频接近悬臂梁的 HR 阵列。评估了带有和不带有 HR 的传感器对声波的响应。开发的带有 HR 的传感器在 RF 上实现了比没有 HR 的传感器高三倍的灵敏度。获得的声压分辨率约为 4 mPa。我们设计并制造了一个尺寸为 80 × 80 × 0.2 µm 和 4.5 kHz 射频的压阻式悬臂梁，以及四个射频接近悬臂梁的 HR 阵列。评估了带有和不带有 HR 的传感器对声波的响应。开发的带有 HR 的传感器在 RF 上实现了比没有 HR 的传感器高三倍的灵敏度。获得的声压分辨率约为 4 mPa。