This letter described ultraviolet (UV) radiation sensing with ZnO based film bulk acoustic-wave resonator (FBAR). The resonant frequency upshifted when there was UV illumination on the FBAR. For 365 nm UV light, the frequency upshift was 9.8 kHz with an intensity of 600 μW/cm2, and the detection limit of the sensor was 6.5 nW. The frequency increase in the FBAR UV sensor was proposed to be due to the density decrease in ZnO film upon UV illumination. When UV was incident on the ZnO film, it can cause oxygen desorption from the ZnO surface, resulting in density decrease in the film. This study has proven the feasibility of detection of low intensity UV using ZnO film based FBAR.
Molecular Electronic Transducer (MET) is a recent technology applied in seismic instrumentation that proves highly beneficial to planetary seismology. MET is an electrochemical cell that senses the movement of liquid electrolyte between electrodes by converting it to the output current. Seismometers based on MET technology are attractive for planetary applications due to their high sensitivity, low noise floor, small size, lack of fragile moving parts and independence on the direction of sensitivity axis. This paper reports an approach to build a micro MET seismometer using Micro-Electro-Mechanical Systems (MEMS) techniques. We have reduced the MET cell size, resulting in internal dimensions close to 1 micrometer (µm). The employment of MEMS improves the sensitivity up to and reproducibility of the device, and has reached 1 micro Gee ( √ ) noise level at 1 Hz.
This paper describes a novel bonding technique using reactive multilayer Ni/Al foils as local heat sources to bond Parylene-C layers to another Parylene-C coating on a silicon wafer. Exothermic reactions in Ni/Al reactive multilayer foils were investigated by x-ray diffraction (XRD) and differential scanning calorimetry. XRD measurements showed that the dominant product after exothermic reaction was ordered B2 AlNi compound. The heat of reaction was calculated to be −57.9 kJ mol −1. A numerical model was developed to predict the temperature evolution in the parylene layers and silicon wafers during the bonding process. The simulation results revealed that localized heating occurred during the reactive foil joining process. Our experimental observation showed that the parylene layer was torn when the bond was forcefully broken, indicating a strong bond was achieved. Moreover, leakage test in isopropanol alcohol showed that reactive foil bonds can withstand liquid exposure. This study demonstrated the feasibility of reactive foil joining for broad applications in bio-microelectromechanical systems and microfluidic systems.
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