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Design, fabrication and test results of a lateral DC-contact RF-MEMS switch for mm-wave applications are presented. The switch is driven by a triple cascaded electrothermal buckle-beam actuator, which can generate large displacements and contact forces at lower temperatures than traditional electrothermal actuators. The size of the whole switch is only 1.2 mm × 1.4 mm in area. The measured transient times for switch-on and switch-off are 13.6 and 0.96 ms, respectively. Low insertion losses and high isolation of 0.17 dB and 26.7 dB, respectively, are obtained in the proposed switch at center frequency of 35GHz, the insertion losses less than 0.5dB and the isolation better than 22.5dB can be achieved in the proposed switch at 30~40GHz. The reasonable agreement between design and measurement is observed.

Fabrication of a novel in-plane field emission diode structure is presented. Sub-micro metal tips were obtained using a two-step lithography method. The Minimum width of the metal tips was less than 100nm, and the minimum spacing of 145.7nm was obtained. The I-V characters in atmospheric environment before and after the silicon etching were measured.

Many MEMS devices including accelerometer and gyroscopes, having moving parts, requires hermetic and low cost packaging. In this paper we propose a low cost fabricating process to prepare micro glass cavity arrays for wafer-level and hermetic packaging of MEMS. First, the fundamental of the process was discussed. Then, the process for preparing cavity arrays in Pyrex7740 glass wafer was studied experimentally. After that, the defects of the fabrication were discussed. Results show that wafer-level packaged cavities were prepared, whose diameter was controllably between 200 microns and 2000 microns. It is also disclosed that the defects could be avoided by controlling the process parameters. Results also show that the leakage rate of the single packaged cavities is below 5Χ10-9 Pa.m/s which could meet the hermetic packaging standard.

Results from both experimental and numerical studies have already shown the significant package effects on the performance and the reliability of MEMS devices. To enable the theoretical predictions of these packaging effects, a compact joint model of an entire packaged MEMS device is established based on the Cell Library Concept and the Nodal Analysis Method. This modeling methodology greatly simplifies the package-device co-design work compared with the conventional numerical ways, and its precision is guaranteed due to its clarity in the physical nature.

To observe the clinical effects of combined type external fixator in treating complex tibial metaphyseal fractures.From January 2007 to July 2012, 34 patients with complex tibial metaphyseal fractures were treated with combined type external fixator in different stagings. There were 23 males and 11 females, with a mean age of 41.3 years (ranged, 16 to 63), and the course of disease were from 1 h to 8 d. In the patients, 31 cases were open fractures, 11 cases with type II, 13 cases with type III A, 7 cases with type III B according with Gustilo classification; 19 cases were tibia plateau fractures, 6 cases with type II, 1 case with type IV, 5 cases with type V, 7 cases with type VI according to Schatzker classification; 15 cases were distal tibial fractures (one were bilateral fractures), 2 fractures with type A2, 1 fracture with type A3, 1 fracture with type C1, 5 fractures with type C2, 7 fractures with type C3 according to AO classification. Rasmussensn scoring system and AOFAS Ankle Hind-foot Scale were respectively used to assess the joint function of knee and hip.Wound surface of 19 patients obtained at phase I healing and 15 patients obtained at phase III healing. Superficial wound infections occurred in 2 cases and bone non-union necessitated reoperation occurred in 2 cases (final fractures obtained bone healing after the second operation). All patients were followed up from 6 to 38 months with a mean of 14.3 months. At the final follow-up,according to Rasmussensn scoring system, 5 fractures got excellent results, 11 good, 3 fair, the mean Rasmussen score was 23.58 +/- 3.98; according to AOFAS Ankle Hind-foot Scale, 5 fractures got excellent results, 8 good, 3 fair, the mean AOFAS Ankle Hind -foot Scale was 80.75 +/- 14.21.Combined type external fixator can well maintain the stability of the fractures, had advantages of low incidences of soft tissue complications and less influence to joint motion in treatment of complicated tibial metaphyseal fractures. However there were some limitations in long-term use.

Adhesion, as one of the most common failure modes compromising reliability of optical MEMS devices, attracted great research interests for enhancing the production yields and device reliability. Experiments show that wet-adhesion with respect to capillary force between interfaces of movable structures is generally the dominant figure among all adhesion natures. Great efforts had been made on examine adhered length of micro-cantilevers to modeling adhesion energy, which are reasonable to predict adhesion in quasi static process such as sacrificial layer release processes. However, the microcosmic mechanism of adhesion has not been well revealed, thereby these models are not sufficiently precise for in-situ adhesion, such as adhesion due to mechanical shock. In this work, a novel model of adhesion energy is derived by review the physical mechanisms carefully and shock caused adhesion is studied applying this model.

Flip chip is one of the advanced packaging technologies, and it has been widely used in MEMS (micro-electromechanical system) packaging due to its manifold advantages compared with the traditional packaging methods. However, there are also many problems to be solved, especially, MEMS sensors are often inherently sensitive to stress induced by their packages because most MEMS sensors include movable structures. In this paper, the thermomechanical characteristic of a flip chip package with different parameters is studied by using the numerical simulation methods .The distribution pattern of flip chip solder bumps including four kinds of all arrays are considered specially, as it is a key design parameter in the technology and has distinct effect on the performance of MEMS sensors with movable structures. The result shows that the position of the structures on the chip should be considered seriously. For the microcantilever and microbridge with 400μm length and 2μm thickness fabricated by surface process, the stress and warpage can lead to a maximum relative change of 5% in the pull-in voltage of a microcantilever and 110% in the first resonant frequency of a microbridge after flip chip packaging, when the temperature changes from 25°C to 125°C.

To determine the reliability of MEMS devices in shock environments, in this paper, we present a method that can be used to formulate the responses of microcantilever under shock loads by taking it as a distributed-parameter system. The displacements and stresses of microcantilever are formulated with the mode superposition method. The failure modes may be estimated by the maximum displacement and stress. This method can be also used in other complicated MEMS structures and devices, therefore the reliability designs of MEMS can be improved greatly.