A nonlinear strain gradient beam formulation

Size dependent buckling analysis of microbeams based on modified couple stress theory with high order theories and general boundary conditions

This work reports on piezoelectric aluminum nitride (AlN) based dual-beam RF MEMS switches that have been monolithically integrated with AlN contour-mode resonators. The dual-beam switch design presented in this paper intrinsically compensates for the residual stress in the deposited films, requires a low actuation voltage (5 to 20 V) and facilitates active pull-off to open the switch and exhibits fast switching times (1 to 2 µs). This work also presents the combined response (cascaded S parameters) of a resonator and a switch that were co-fabricated on the same substrate. The response shows that the resonator can be effectively turned on and off by the switch. A post-CMOS compatible process was used for the co-fabrication of both the switches and the resonators. The single-chip RF solution presented constitutes an unprecedented step forward towards the realization of compact, low-loss and integrated multi-frequency RF front-ends.

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Dual-Beam Actuation of Piezoelectric AlN RF MEMS Switches Monolithically Integrated with AlN Contour-Mode Resonators

Analytical solutions for the size dependent buckling and postbuckling behavior of functionally graded micro-plates

This paper reports on the implementation of low-voltage complementary mechanical logic achieved by using body-biased aluminum nitride (AlN) piezoelectric microelectro-mechanical systems (MEMS) switches. By biasing the equivalent body of a four terminal mechanical switch with a fixed voltage, the threshold voltage of the mechanical transistor has been precisely tuned and the voltage swing used for implementing digital functionalities reduced to very low values (≤ ±2 V). Thanks to the use of a mechanical switching mechanism, the AlN MEMS switches have exhibited an extremely low subthreshold slope (0.065 mV/dec), which sets the promise for even further reduction of the voltage swing to less than 100 mV. By using opposite body biases, the same mechanical switch has been made to operate as an equivalent n-like or p-like (complementary) device. Two basic AlN mechanical switch elements have then been used to form a body-biased inverter operating at 100 Hz with a ±1.5-V voltage swing. Furthermore, low voltage and functionally complete logic elements (NAND and NOR) implemented by using body-biased complementary and thin-film (250 nm thick) AlN-based piezoelectric mechanical switches have been synthesized. Finally, scaling rules for these devices are derived, and the key challenges that will need to be addressed to achieve further miniaturization are presented.

Body-Biased Complementary Logic Implemented Using AlN Piezoelectric MEMS Switches

A radio-frequency micro-electro-mechanical systems (RF MEMS) switch with bistable states based on electromagnetic actuation is presented The switch has two stable positions due to the adoption of the permanent magnets, which will lead to a lower power consumption of the device With electromagnetic actuation arising from the planar coils, the cantilever beam can switch from one stable position to the other The structure sizes of the switch are simulated by the finite element software of the ANSYS 70 The device with a size of 20 mm × 22 mm is fabricated by UV-LIGA technology A current pulse with an amplitude of 50 mA is needed for the fabricated switches’ switching between two stable states that is in good agreement with the simulation, and the switching time is only approximately 20 μs The insertion loss is −011 dB, and the isolation is −43 dB at 3 GHz

Preparing of a high speed bistable electromagnetic RF MEMS switch

A radio-frequency micro-electro-mechanical systems (RF MEMS) switch with two stable states based on electromagnetic actuation is presented. The switch has two stable positions due to the use of the permanent magnets, which will lead to a low power consumption of the device. The micromechanical structure of the switch is designed and analyzed by means of mechanics and electromagnetism. The results show that the 13-/spl mu/m displacement of the cantilever beam in the switch model with stiffening rib can be achieved with the force of 20/spl mu/N on the beam, and the natural frequency of the switch is about 5600Hz. Electromagnetic analysis reveals that the driving force of 20/spl mu/N can be obtained by magnetic interaction.

Design and analysis of the micromechanical structure for an electromagnetic bistable RF MEMS switch

A fast switching electromagnetic microactuator with two stable positions is presented. The actuator of size 2.0×2.2 mm is fabricated using UV-LIGA technology. Test results show that a current pulse with an amplitude of 50 mA is needed for the actuator's switching between two stable states, and the switching time is approximately 20 µs. The displacement of the actuator is about 17 µm.

Fast switching bistable electromagnetic microactuator

Laminated photoresist sacrificial layer process has been developed to fabricate suspended micro-structures. Different problems related to the process such as air bubble, crack, crinkle, black floccule and adhesion are discussed and their solutions are proposed. The perfect suspended structure is successfully achieved utilizing wet release technology with in-sequence-removal method for the e tching of the laminated photoresist and in-sequence-displacement method forthe release of cantilever beam. The distance is about 10 μm from the substrate to the cantilever beam with a length of 1400 μm, a thickness of 6 μm and a width of 40 μm.

Bingchu Cai

Papers

Preparing of a high speed bistable electromagnetic RF MEMS switch

Design and analysis of the micromechanical structure for an electromagnetic bistable RF MEMS switch

Fast switching bistable electromagnetic microactuator

Laminated Photoresist Sacrificial Layer Technology for MEMS