A novel microcantilever sensor was batch fabricated for Yersinia detection. The microcantilever surface modification method was optimized by introducing a secondary antibody to increase the number of binding sites. A novel microfluidic platform was designed and fabricated successfully. A 30 μL solution could fully react with the microcantilever surface. Those routines enhanced the binding efficiency between the target and receptor on the microcantilever. With this novel designed microfluidic platform, the specific adsorption of 10⁷ Yersinia on the beam surface with modified F1 antibody was significantly enhanced.

Sn-rich Au–Sn solder bonding has been systematically investigated for low temperature wafer-level hermetic packaging of high-end micro-electro-mechanical systems (MEMS) devices. The AuSn2 phase with the highest Vickers-hardness among the four stable intermetallic compounds of the Au–Sn system makes a major contribution to the high bonding strength. A maximum shear strength of 64 MPa and a leak rate lower than 4.9 × 10−7 atm-cc s−1 have been obtained for Au46Sn54 solder bonded at 310 °C. In addition, several routines have been used to effectively inhibit the solder overflow and preserve a good bonding strength and water resilience: producing dielectric SiO2 structures which do not wet the melting solder to the surrounding bonding region, reducing the bonding pressure, and prolonging the bonding time. This wafer level bonding technique with good hermeticity can be applied to MEMS devices requiring a low temperature package.

This paper presents a wafer-level three-dimensional (3D) vacuum packaging technique for radio frequency microelectromechanical systems (RF MEMS) resonators. A Sn-rich Au–Sn solder bonding is employed to provide a vacuum encapsulation as well as electrical conductions. Vertical silicon vias are micro-fabricated by glass reflow process. The optimized grounding, via pitch, and all-round shielding effectively reduce feed-through capacitance. Thus the signal-to-background ratios (SBRs) of the transmission signals increase from 17 dB to 20 dB, and the quality factor ( Q ) values of the packaged resonators go from around 8000 up to more than 9500. The measured average leak rate and shear strength are (2.55 ± 0.9) × 10 ⁻⁸ atm-cc s ⁻¹ and 42.53 ± 4.19 MPa, respectively. Furthermore, thermal cycling test between −40 °C and 100 °C and high temperature storage test at 150 °C show that the resonant-frequency drifts are less than ±7 ppm. In addition, the SBRs and the Q values have no obvious change after the tests. The experimental results demonstrated that the proposed encapsulation technique is well suited for the applications of RF MEMS devices.

Resonators with multi-frequency generations at the device-level are highly desired in the future multi-band, reconfigurable, and compact wireless communications. In this work, a switchable radio frequency micro-electro-mechanical system (RF-MEMS) resonator with multiple electrodes is presented. The resonator is designed to operate at the whispering gallery modes (WGMs). Simultaneous excitations of the second to seventh modes with high Q values are implemented within a single device using a pair of electrodes for driving and sensing. For effective multi-frequency excitations, the electrode span angle is optimized. The frequencies of the 37 μm and 18 μm-radius resonators range from 53 MHz to 176 MHz and 112 MHz to 366 MHz, respectively. The Q values in each mode are over 10⁴. Moreover, with the multi-electrode configurations, the specific mode can be enhanced with other modes suppressed. A more than 6 dB improvement of the spectrum peak is realized and the high Q values are maintained. A comprehensive theory is built up to clarify the driving/sensing principles under different electrode configurations. Furthermore, the air damping is found to have a significant effect on Q values for resonator with high stiffness vibrating in all the WGMs. The Q values in vacuum have at least two times improvement. The high-performance switchable resonator could dramatically reduce the power consumption, simplify the processing circuits, and occupy less footprint, which has great potential applications in future advanced RF front end systems.