We proposed a multi-frequency sandwich type vibration energy harvester to widen the effective frequency range of vibration energy harvester. The harvester is composed of three resonant structures with different natural frequencies. The resonant structures are two cantilevers each with bi-layer coils and a plane spring with a magnet. The maximum peak-peak voltages of the three different frequencies are 172 mV, 104 mV and 112 mV at the frequencies of 235 Hz, 330 Hz and 430 Hz, respectively. The first maximum voltage is much higher than the others, because the coils in both cantilevers can produce voltages.

Microfluidic chips were designed and fabricated to capture cells in a relative small volume to generate the desired concentration needed for analysis. The microfluidic chips comprise 3D cell capture structures array fabricated in PDMS. The capture structure includes two layers. The first layer consists of spacers to create small gap between the upper layer and glass. The second layer is a sharp corner U-shaped compartment with sharp corners at the fore-end. And another type capture structure with Y-shaped fluidic guide has been designed. It was demonstrated that the structures can capture cells in theory, using Darcy-Weisbach equation and COMSOL Multiphysics. Then yeast cell was chosen to test the performance of the chips. The chip without fluid guides captured approximately 1.44×105 cells and the capture efficiency was up to 71%. And the chip with fluid guides captured approximately 5.0×104 cells and the capture efficiency was approximately 25%. The chip without fluid guides can capture more cells because the yeast cells in the chip without fluid guides are subject to larger hydrodynamic drag force.

tThis article introduces a novel type of MEMS probe card that uses polymer (polydimethylsiloxane, PDMS)as an elastic layer. The elastic layer provides the flexibility when the probes are in contact with the chippads. Through-holes in the PDMS and the low temperature co-fired ceramic (LTCC) substrate lead thesignals or power to the back side of the LTCC substrate. The proposed MEMS probe card configurationpotentially improves the probe density and simplifies the fabrication process. The probes are formedby electroplating on the PDMS substrate. The PDMS elastic substrate probe card with a probe pitch of100 m was developed for area array pad testing. The contact force is approximately 18 mN when theprobes overdrive is 20 m. Coplanar waveguides structures can be fabricated on the PDMS surface. Themeasured insertion loss is 0.2 dB at 3 GHz.The test data exhibited that the PDMS elastic substrate probecard is suitable for high-frequency wafer level IC testing.

设计了一种新型的脑电图干电极, 主要用于采集脑电信号以进行基于脑电图的警觉度分析, 替代传统的湿电极. 采用柔性衬底微电子机械系统( MEMS) 加工技术, 在柔性衬底上制备出具有化学稳定性与生物相容性的微针状干电极阵列. 通过铜牺牲层实现干电极微针的悬臂梁结构, 利用聚二甲基硅氧烷( PDMS) 剥离层实现器件从玻璃基底的完全释放, 并经平面电极的多层组装实现了立体电极阵列. 实验中干电极以聚酰亚胺作为柔性衬底, 其针端及导线部分材料为镍, 针端部分表面镀金. 采用Neuroscan 的脑电信号采集放大器对干电极性能进行了测试, 测得阻抗约为10k 8, 其时域和频域信号与传统湿电极基本一致. 所制备的干电极成品率高、尺寸小、屏蔽佳、装配简单、可靠性好、机械强度大, 符合快速、无痛的脑电信号采集要求。

Electroencephalogram (EEG) has been one of the important means to study brain functions and diseases.We fabricated an innovative MEMS elastic-based dry electrode using photolithography and electroforming process.The pitch of elastic-based dry electrode tip is 100 lm.We adopted polydimethylsiloxane as an elastic layer which provides the flexibility when the conductive layer and the electrode tip contact with the skin. This kind of dry electrode array does not need conductive gel during testing procedure. Compared with the traditional Ag/AgCl wet electrode, it greatly reduced the preparation time for EEG measurement and it could make the examinee more comfortable.