Thermoelectric Energy Micro Harvesters with Temperature Sensors Manufactured Utilizing the CMOS-MEMS Technique.

This study develops a TEMH (thermoelectric energy micro harvester) chip utilizing a commercial 0.18 µm CMOS (complementary metal oxide semiconductor) process. The chip contains a TEMH and temperature sensors. The TEMH is established using a series of 54 thermocouples. The use of the temperature sensors monitors the temperature of the thermocouples. One temperature sensor is set near the cold part of the thermocouples, and the other is set near the hot part of the thermocouples. The performance of the TEMH relies on the TD (temperature difference) at the CHP (cold and hot parts) of the thermocouples. The more the TD at the CHP of the thermocouples increases, the higher the output voltage and output power of the TEMH become. To obtain a higher TD, the cold part of the thermocouples is designed as a suspended structure and is combined with cooling sheets to increase heat dissipation. The cooling sheet is constructed of a stack of aluminum layers and is mounted above the cold part of the thermocouple. A finite element method software, ANSYS, is utilized to compute the temperature distribution of the TEMH. The TEMH requires a post-process to obtain the suspended thermocouple structure. The post-process utilizes an RIE (reactive ion etch) to etch the two sacrificial materials, which are silicon dioxide and silicon substrate. The results reveal that the structure of the thermocouples is completely suspended and does not show any injury. The measured results reveal that the output voltage of the TEMH is 32.5 mV when the TD between the CHP of the thermocouples is 4 K. The TEMH has a voltage factor of 8.93 mV/mm2K. When the TD between the CHP of the thermocouples is 4 K, the maximum output power of the TEMH is 4.67 nW. The TEMH has a power factor of 0.31 nW/mm2K2.

Prophylactic effects of hyperforin on anhedonia-like phenotype in chronic restrain stress model: A role of gut microbiota.

Anhedonia is the core symptom of depression, which largely reflects the therapeutic effect of depression. Hypericum perforatum is one of the most important antidepressant herb that has fewer side effects than traditional antidepressants. Considering the antibacterial effect of Hypericum perforatum, we verified whether this antidepressant activity was related to intestinal microbiomics. So we established anhedonia mouse model to explore the underlying treatment mechanism of hyperforin, the key antidepressant ingredient of Hypericum perforatum and to screen new psychobiotics based on hyperforin. It was found that hyperforin prevented anhedonia induced by chronic restraint stress in mice and altered the richness and evenness of bacteria populations compared with stressed mice. Metastat analysis showed that Akkermansia muciniphila and Muribaculum intestinale were the bacterial species obviously affected by hyperforin, and their abundance in hyperforin-treated group significantly increased. The results suggest that the effect of hyperforin on anhedonia may be partly assisted by Akkermansia muciniphila. These also indicate that Muribaculum intestinale may be another important intestinal bacteria involved in the pathogenesis of anhedonia symptom and depression.

Manufacturing and Testing of Radio Frequency MEMS Switches Using the Complementary Metal Oxide Semiconductor Process.

A radio frequency microelectromechanical system switch (MSS) manufactured by the complementary metal oxide semiconductor (CMOS) process is presented. The MSS is a capacitive shunt type. Structure for the MSS consists of coplanar waveguide (CPW) lines, a membrane, and springs. The membrane locates over the CPW lines. The surface of signal line for the CPW has a silicon dioxide dielectric layer. The fabrication of the MSS contains a CMOS process and a post-process. The MSS has a sacrificial oxide layer after the CMOS process. In the post-processing, a wet etching of buffer oxide etch (BOE) etchant is employed to etch the sacrificial oxide layer, so that the membrane is released. Actuation voltage for the MSS is simulated using the CoventorWare software. The springs have a low stiffness, so that the actuation voltage reduces. The measured results reveal that actuation voltage for the MSS is 10 V. Insertion loss for the MSS is 0.9 dB at 41 GHz and isolation for the MSS is 30 dB at 41 GHz.

Low-Concentration Ammonia Gas Sensors Manufactured Using the CMOS-MEMS Technique.

This study describes the fabrication of an ammonia gas sensor (AGS) using a complementary metal oxide semiconductor (CMOS)-microelectromechanical system (MEMS) technique. The structure of the AGS features interdigitated electrodes (IDEs) and a sensing material on a silicon substrate. The IDEs are the stacked aluminum layers that are made using the CMOS process. The sensing material; polypyrrole/reduced graphene oxide (PPy/RGO), is synthesized using the oxidation-reduction method; and the material is characterized using an electron spectroscope for chemical analysis (ESCA), a scanning electron microscope (SEM), and high-resolution X-ray diffraction (XRD). After the CMOS process; the AGS needs post-processing to etch an oxide layer and to deposit the sensing material. The resistance of the AGS changes when it is exposed to ammonia. A non-inverting amplifier circuit converts the resistance of the AGS into a voltage signal. The AGS operates at room temperature. Experiments show that the AGS response is 4.5% at a concentration of 1 ppm NH3; and it exhibits good repeatability. The lowest concentration that the AGS can detect is 0.1 ppm NH3.