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2,4,6-trinitrotoluene (TNT) has a strong explosive force and environmental toxicity, with the increasing threat of terrorist attacks worldwide, the high sensitivity detection of nitroaromatic explosives has become an urgent problem to be solved, and now the commonly used detection method is to use the optical principle, combined with large and expensive equipment to detect it. In order to detect the content of TNT in bad environment quickly and in real time, surface acoustic wave technology was proposed to detect different concentrations of TNT. In this paper, an ultra-sensitive TNT sensor was fabricated based on the surface acoustic wave technique. Specific detection of TNT was achieved by recognizing the shift of resonance frequency. Moreover, the whole process for the detection was done in 30 min, dedicating the rapid/real-time application of the sensor. This study focused on the transfer characteristics of resonance frequencies at different concentrations. The frequency of surface sound waves varies greatly at high concentration because the modified IDT (interdigital transducers) electrodes were utilized, which is easy to work under different concentrations of TNT. The proposed sensor has the advantages of real-time, simple and convenient detection, which provides a valuable method for the real-time detection of TNT.

The reliability analysis of MEMS gyroscope under long-term operating condition has become an urgent requirement with the enlargement of its application scope and the requirement of good durability. In this study we propose a lifetime prediction method for MEMS gyroscope based on accelerated degradation tests (ADTs) and acceleration factor model. Firstly, the degradation characteristic (bias instability) is extracted based on Allan variance. The effect of temperature stress on the degradation rate of bias instability is analyzed, and it shows that the degradation rate of bias instability would increase with the increase of the temperature. Secondly, the ADTs of MEMS gyroscope are designed and conducted, the degradation model of MEMS gyroscope is established based on the output voltage of MEMS gyroscope and Allan variance. Finally, the acceleration factor model of MEMS gyroscope under temperature stress is derived, and the lifetime of the MEMS gyroscope is predicted based on two group tests data under high stress level. The results show that the lifetime calculated by the acceleration factor model and mean lifetime under high stress levels is close to the mean lifetime calculated by the linear equation at normal temperature stress.

A novel micro shell resonator gyroscope (MSRG) with 16 T-shape masses using out-of-plane electrodes is proposed in this paper. The T-shape masses are designed for high transduction efficiency. Out-of-plane electrodes are used to drive and detect the spatial deformation of the resonator. The finite element method (FEM) is applied to evaluate the influence of the T-shape mass on transduction efficiency. Compared with the MSRG without the T-shape masses, the FEM results reveal that the MSRG with T-shape masses has shown an increase of 42% on effective mass ( ${M}_{ {eff}}$ ) and a decrease of 8% on ${f}_{ {n=2}}$ . For the MSRG without T-shape mass, spherical–cylindrical, spherical, and out-of-plane electrodes have been applied to drive and sense n = 2 wineglass modes. Compared with the MSRG without T-shape using out-of-plane electrodes, the MSRG with T-shape masses has showed the improvement of 334%, 522%, and 598% on driving efficiency ( ${S}_{ {d}}$ ), detection efficiency ( ${S}_{ {s}}$ ), and mechanical sensitivity ( ${S}_{ {mech}}$ ) due to large ${M}_{\text {eff}}$ and electrode area. In addition, the improvement of 15% in the thermal noise of a gyroscope (ARW $_{\text {mech}}$ ) is dominated by a large effective mass, contributing to the improvement of signal-to-noise ratio. The process of micro blow torching with the whirling platform and femtosecond ablation is presented to fabricate the MSRG with T-shape masses. The performance of MSRG is demonstrated experimentally with out-of-plane capacitive transduction. The MSRG is operated in the force-rebalance mode, which demonstrates a scale factor of 0.107V/(°/s), an angle random walk of 0.099°/ $\text{h}^{{1/2}}$ , and a bias instability of 0.46°/h, showing a great potential for high-performance gyroscopic application.

This paper presents a novel method to achieve permanent frequency trimming between wineglass modes of micro shell resonator (MSR) with T-shape masses (T-masses) using femtosecond laser ablation. Trimming effects on stiffness and mass distribution around the rim are analyzed by finite element method (FEM). Stiffness and mass trimming can be achieved by grooves ablating in different positions. A systematic frequency trimming process including stiffness and mass modification is proposed. FEM simulation is further applied to estimate the variation of cross coupling and frequency split during the trimming process. High resolution trimming without surface deterioration is achieved by using a low-power femtosecond laser. Finally, frequency trimming experiments were implemented on imperfect resonators. Test results show that frequency split can be effectively reduced to less than 0.5Hz within several steps, demonstrating the effectiveness of this method.

Electromechanical phonon-cavity systems are man-made micro-structures, in which vibrational energy can be coherently transferred between different degrees of freedom. In such devices, the energy transfer direction and coupling strength can be parametrically controlled, offering great opportunities for both fundamental studies and practical applications such as phonon manipulation and sensing. However, to date the investigation of such systems has largely been limited to linear vibrations, while their responses in the nonlinear regime remain yet to be explored. Here, we demonstrate nonlinear operation of electromechanical phonon-cavity systems, and show that the resonant response differs drastically from that in the linear regime. We further demonstrate that by controlling the parametric pump, one can achieve nonlinearity-mediated digitization and amplification in the frequency domain, which can be exploited to build high-performance MEMS sensing devices based on phonon-cavity systems. Our findings offer intriguing opportunities for creating frequency-shift-based sensors and transducers.

This article reports a MEMS type Damping Viscous Vacuum Gauge(DVVG) for high vacuum measurement. This gauge, based on squeeze film damping effect that gases exerts on moving block with high velocity and constructed by MEMS technology, was reported for the first time. The working principle, manufacturing process and measurement steps were introduced in detail. This gauge, comparing with the existing DVVG has the advantages of smart size and lower price that could meet the requirement of embedded measurement requirement, for example, leakage rate detection of tiny vacuum chamber. The third-order mode was applied to measure vacuum degree, test result shows that measurement range covers 7.5×10-5Pa to 5×10−3Pa with especially high sensitivity (superior than 10-5Pa) and output linearity(R2=0.9978 ) between 1×10−4 Pa and 1×10−3Pa.

This paper reports a simple novel method of effective quality factor (Q eff ) tuning by mechanical pumping. Through the red (anti-stokes) and blue (stokes) sideband activating, Q eff of the coupled MEMS resonator can be considerably adjusted. It is demonstrated that the decay time of the resonator can be greatly enhanced to 60.54 s (more than 100 times), which can be equivalent to a million-order (1.32 million) Q eff MEMS resonator. Additionally, the phenomenon of self-oscillation is observed at the blue sideband, which provides a new method of mode driving and mode locking without harmonic driving signal. Finally, the approach in this paper is also widely applicable to other MEMS/NEMS resonators, which may be useful for further researches on MEMS/NEMS sensors with high accuracy.

This paper reports a novel wafer-level vacuum packaging method based on TGV (Through Glass Via) technology for MEMS devices. For the first time, it is reported that the vacuum packaging is achieved by TGV scheme combined with triple anodic bonding (TGV substrate, MEMS structure and glass cap), which will bring more stable vacuum packaging, lower packaging stress and lower parasitic capacitance. As a crucial step, glass reflow process was analyzed theoretically and experimentally to improve the sealing performance of TGV substrate itself. And the CMP (Chemical Mechanical Polish) technology for TGV substrate, which polishes glass and silicon at the same time, was also researched and ameliorated to obtain a smooth surface for excellent strength of triple anodic bonding. Finally, a MEMS gyroscope was packaged without getter, and the packaged pressure was calibrated to be about 90Pa, demonstrating the feasibility of this packaging scheme.

In this paper, we present a novel method to improve the quality factor in disk resonator gyroscopes (DRGs) by optimizing the spoke length distribution (SLD). As for DRGs with identical outer radius R, anchor radius r, ring width h, ring numbers n and spoke length boundaries [a, b] whereas with different SLDs, finite element simulation results show that the SLDs have a great influence on the DRGs’ resonant frequency $\text{f}_{0}$ and thermoelastic quality factor ( $\text{Q}_{\mathrm {TED}}$ ). This paper aims to find an optimized SLD to achieve the highest $\text{Q}_{\mathrm {TED}}$ of a DRG. By using the particle swarm optimization method the optimum SLD of a 9-ring DRG is obtained and the $\text{Q}_{\mathrm {TED}}$ is greatly improved. By further applying this method on the DRGs with different structural parameters, the regular rules of the optimum SLD are concluded and a simple method to get the optimized SLD for a DRG is proposed. By applying the method on the DRGs with different ring widths and ring numbers, the $\text{Q}_{\mathrm {TED}}$ of them can be improved by 25%-43%. This demonstrates that the method is effective for the $\text{Q}_{\mathrm {TED}}$ improvement. With this method, designers can easily obtain the optimized SLD in a DRG after the parameters R, r, h, and n are determined to further improve the DRG’s quality factor. [2017–0259]

The through glass via (TGV) substrate plays an important role in wafer-level vacuum packaging of micro-electro-mechanical system (MEMS) devices. The airtightness of TGV is critical for it but difficult to achieve. Therefore, the solid–liquid interface energy was considered to enhance airtightness. Theoretical analysis revealed that the solid–liquid interface energy between the melted glass and SiO2 was higher than that between the melted glass and Si. Experiments were designed and conducted to verify the finding. The driving-mode quality factor of gyroscopes sealed by TGV with a layer of SiO2 was measured to be 9119 while the driving-mode quality factor was only 130 without a layer of SiO2, with the latter value nearly equivalent to that in the atmosphere. According to the calibration of vacuum degree, the driving-mode quality factor (9119) indicated that the internal air pressure was about 100 Pa, which shows the feasibility of TGV with a layer of SiO2 for wafer-level vacuum packaging.

This paper presents a novel micro shell resonator (MSR) with T-shape masses based on fused silica using out-of-plane electrode structures. Eight circular-distributed T-shape masses are designed along the rim of resonator shell to improve transduction efficiency, including drive efficiency and detection efficiency. The dynamic parameters and transduction efficiency are calculated and optimized with finite element method, revealing 3.76 times improvement in drive efficiency, 4.65 times improvement in detection efficiency, and 17.81 times increase in mechanical sensitivity. In addition, it is feasible to trim the frequency by adding or removing mass on the T-shape masses. The key feature of the process is based on micro blow-torching process and whirling platform, which form the resonator structure with smooth roughness and good structure uniformity. Femtosecond laser ablation is used to release the T-shape masses for good symmetry and high processing quality. Then, metalized MSR with T-shape masses is assembled on a glass substrate. Electrostatic transduction is used to detect spatial deformation of resonators by out-of-plane electrodes, which reveals a frequency mismatch of 0.175% at 6904.4 Hz and 6916.5 Hz with quality factors of 20.39 k ( $\tau =0.94$ s) and $Q = 36.94$ k ( $\tau =1.7\text{s}$ ). [2017-0086]

A Micro-Electro-Mechanical-System (MEMS) resonant vacuum gauge (RVG) based on the electrostatic nonlinearity for low vacuum measurement was introduced. Different natural resonance modes of the sensing unit were driven for vacuum measurement. There were three modes driven under different pressure to measure the relationships between resonance frequency and gas pressure, including the second-order resonant mode (the second mode in short), the third mode and the fourth mode. The second mode was independent of gas pressure variation. The third mode measurement range nearly covered 1–500 Pa, and the linear fitting showed an excellent output linearity (R2 = 0.995) and resolution (more than 0.5 Pa). The measurement range of the fourth mode covered 1–4000 Pa, and the fitting results showed high linearity (R2 = 0.997) and about 1 Pa of resolution.

Ultrafast pulsed lasers can facilitate the manufacturing of complex microstructures. However, previous laser processing applications have focused on static components. Consequently, the application of laser processing in high-performance resonant structures has received less attention. Ultrafast lasers provide a unique opportunity for realizing the structure detachment from the planar fused silica substrates. However, the processing quality has a considerable influence on resonant structures. High-quality and high-efficiency laser manufacturing methods are critical for processing resonant structures. In this study, we demonstrate a method for processing fused silica microstructures based on the femtosecond laser. We studied the influence of different laser parameters on the processing quality and determined the optimal laser parameters suitable for the microstructure. The resonant structure of the butterfly gyroscope was used to verify the manufacturing method. A steepness of 86.6° and a roughness of 653.2 nm were achieved by using the optimized laser parameters. These are expected to provide technical support for the development of high-performance fused silica dynamic devices in the future.

This paper introduces a utility algorithm to reduce the permanent frequency mismatch of the primary wineglass modes in a disk resonator gyroscope via stiffness perturbation. In this algorithm, each tuning electrode is regarded as two rows of radial springs with negative stiffness. On the basis of the tuning model for a ring with radial springs, we can obtain the functional relation between equivalent stiffness or voltage of each tuning electrode and the frequency split. Corresponding simulations are conducted to demonstrate the performance of the algorithm. Finally, the electrostatic tuning experiment is presented to further verify the algorithm and illustrate the use of the tuning procedure. Results of experiment show that the frequency split of resonator is decreased to smaller than 0.03 Hz from original about 15 Hz.

This paper presents a comprehensive investigation of the influences of the structure parameters on the sensitivity and Brownian noise of the disk resonator gyroscope (DRG). The mechanical sensitivity, transducer sensitivity, Brownian displacement, and Brownian noise floor of the DRG with varying structural parameters (including ring number, resonator diameter, structure height, and anchor size) are calculated based on the finite-element method (COMSOL Multiphysics). Each parameter is studied independently. Meanwhile, useful comparison between the DRG and the ring vibratory gyroscope is made, which indicates that the DRG has great advantages over the transducer sensitivity and Brownian noise. Last but not least, a multi-objective optimization method is used to design the ring thickness distribution of the DRG and an instructive ring thickness distribution designing rule is obtained. The preceding study can give an explicit guideline for designing all kinds of DRG and may also provide useful information for designing other micro gyroscopes. The multi-objective optimization method could be expanded to include other objectives, constraints, or variables relevant to all kinds of gyroscopes or other microelectromechanical systems devices.

This paper reports the design, simulation, fabrication and measurement of a double differential torsional micro-accelerometer based on V-shape beam. The structure of conventional torsional micro-accelerometers is typically composed of two unbalanced proof masses and a torsional beam. This work develops a torsional micro-accelerometer with an optimized structure, which is composed of four proof masses splitting into two pairs. The two pairs of unbalanced masses have the opposite sensitivity to acceleration but the same sensitivity to off-acceleration input, and by using double differential arithmetic the sensitivity, environment robustness and bias stability can be improved. The accelerometer prototype is fabricated with the pre-buried mask wet-etching method and tested. The resonant frequency and quality factor are about 1485 Hz and 28.02 respectively. The sensitivity and nonlinearity of the measuring range ±15 g is 0.14 mV/g and 0.22% respectively. The x-axis and y-axis cross-axis errors are 0.04% and 0.69% respectively. The 1 g bias stability of the accelerometer is 0.11 mg for 1 h and the Allan deviation is 8.7 μg. In the full temperature range of −40 °C to +60 °C,the temperature sensitivity of the scale factor is 49.9 ppm/°C while the offset temperature coefficient is 0.22 mg/°C after temperature compensation.

MEMS gyros installed in modern complex systems, like aircraft systems and industrial control system, are mainly subjected to mechanical vibrations in applications. Therefore, the failure of the MEMS gyro under random vibration was studied by the finite element method (FEM) and step test in this paper. Firstly, the mechanism of the output accuracy reduction of MEMS gyro under random vibration was analyzed. Then the displacement variation of MEMS gyro's sensitive structure in three different directions and the stress distribution under random vibration was analyzed by FEM, and the results showed that the key failure location of the MEMS gyro is the intersection of the slanted beam and the trapezoidal beam. MEMS gyros have been tested to failure by subjecting to a wide-band (15Hz-2KHz) random vibration step test with root mean square accelerations of 3g, 6g, 25g, 30g, 35g, 45g, 50g, 55g, 60g and 62.5g. The test results showed that the MEMS gyro can withstand a limit root mean square acceleration of 62.5g, and the failure position is consistent with simulation results by FEM, the reason of the failure was analyzed.

This paper reports a wafer-level fabrication process for micro hemispherical resonators. Three-dimensional (3-D) structures are formed by high-temperature glassblowing individually to further enhance the structural symmetry. And then these structures are aligned and mounted on a 4-inch jig wafer, following processes including ultrafast laser ablation, metallization and bonding to electrode wafer are accomplished on wafer level. 3-D fused silica resonators with extremely symmetry, easy-operation and compatibility to MEMS procedure are simultaneously realized in this process. Devices with capacitive gap ≈15µm and alignment error below 35 µm are realized. Finally, these devices are characterized through capacitive measurement in vacuum, with n=2 wineglass mode ranging from 8.9 kHz to 9.7 kHz and quality factors between 47,073 to 55,026. The process is promising for the manufacturing of high-performance MEMS devices such as micro hemispherical resonator gyroscopes (µHRG).

A novel micro shell resonator gyroscope (MSRG) with sixteen T-shape masses is proposed in this paper. Micro blow torching with whirling platform has been presented to fabricate the fused silica shell structure with high structure symmetry. The sixteen T-shape masses are released with femtosecond laser ablation for high processing efficiency and quality. The performances of MSRG are evaluated by using out-of-plane capacitive transduction. The MSRG is operated in force-rebalance mode, which demonstrates a scale factor (SF) of 0.112V/(deg/s), an angle random walk (ARW) of 0.035deg/√h and a bias stability of 0.877deg/h, showing great potential for high-performance gyroscope.

This paper reports a method to improve the quality factor of the honeycomb-like disk resonator gyroscope (HDRG). Based on this method, a novel HDRG prototype is designed, fabricated and tested. The new-designed HDRG has a more than 4-fold increase of tested quality factor compared with the former design, resulting in about 3 times improvement of angular random walk and 30 times improvement of bias-instability.