Resonant Pressure Micro Sensors Based on Dual Double Ended Tuning Fork Resonators

Abstract

This paper presents resonant pressure micro sensors based on dual double ended tuning fork (DETF) resonators, which are electrostatically excited and piezoresistively detected. In operation, the barometric pressure under measurement bends the pressure sensitive diaphragm functioning as the anchor of DETF resonators and therefore produces eigenfrequency shifts of the resonators. Theoretical analyses and finite element analyses (FEA) were conducted to optimize the key geometries of the DETF resonators with enhanced signal to noise ratios (SNRs). In fabrications, key steps including deep reactive ion etching (DRIE) and anodic bonding were used, where sleeve holes were adopted to form electrical connections, leading to high-efficiency structure layout. Experimental results indicate that the presented micro sensors produced SNRs of 63.70 ± 3.46 dB in the open-loop characterizations and differential sensitivities of 101.3 ± 1.2 Hz/kPa, in the closed-loop characterizations. In addition, pressure cycling tests with a pressure range of 5 to 155 kPa were conducted, revealing that the developed micro sensors demonstrated pressure shifts of 83 ± 2 ppm, pressure hysteresis of 67 ± 3 ppm, and repeatability errors of 39 ± 2 ppm. Thus, the developed resonant pressure micro sensors may potentially function as an enabling tool for barometric pressure measurements.

Stress isolations for resonant pressure micro sensors

“…Figure 3(a) shows the fabrication process, which closely aligns with our previous works [13,14] but with a few innovative additions (Figure 3 (a v-vii)). The main difference was that a silicon wafer was utilized as an isolation layer.…”

Design and Optimization of MEMS Resonant Pressure Sensors with Wide Range and High Sensitivity Based on BP and NSGA-II

“…Therefore, a smaller width rather than height is chosen in the structure design. Based on the resonant beam parameters and resonant frequencies of the existing structures [10,11,14], a resonant beam structure with a length of 1200 µm, a width of 20 µm, and a height of 40 µm is selected with an intrinsic frequency of 120 kHz. Preliminary structural models have been established, and dynamic analysis of the structure has been conducted using COMSOL.…”

Wide-range, durable, and adaptable miniature pressure sensor based on planar capacitance

“…[1][2][3], industrial equipment [4], human-machine interfaces [5,6], wearable electronics [7], and robotics [8,9]. In recent years, studies on the operating mechanism of miniature pressure sensors have focused on piezoresistive [10][11][12][13][14][15][16], piezoelectric [17,18], resonant [19,20], fiber optic [21], and capacitive sensors [22]. Among them, capacitive miniature pressure sensor has the advantages of high resolution, high stability, and low energy consumption (table S1) [22][23][24][25][26][27], making it an ideal choice for miniature region pressure detection [28,29].…”