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A three-parameter sensor based on a point-by-point fiber Bragg grating (PBP-FBG) is proposed. The fabricated sensor is 40 mm long. The spectrum loss at 1336.15 nm is selected to measure the surrounding liquid level. The sensitivity for liquid level sensing is −0.046 dB/mm. The temperature is measured using the Bragg dip shifts with sensitivity of 10.06 pm/ °C. The cut-off mode shift is used to measure the surrounding refractive index with sensitivity of 535.14 nm/RIU. As a benefit of femtosecond laser direct inscription fabrication, the grating length is controllable and the liquid level sensing range is expandable. This sensor provides a simple, reliable method for accurate liquid level, temperature and refractive index measurements in hazardous environments. [ABSTRACT FROM AUTHOR]

In this article, we report a wafer-level packaged Pirani vacuum gauge using the proprietary InvenSense CMOS MEMS technology. The micro Pirani vacuum gauge features three serpentine-shaped molybdenum thermistors on the suspended silicon-on-insulator (SOI) bridges, while the wiring gap of each serpentine-shaped silicon microbridge is 1.6 ${ {\mu }}\text{m}$. For the vacuum range of $5\times 10^{-{4}}$ –760 Torr, the CMOS MEMS Pirani gauge configured with a constant temperature interface circuit achieves a sensitivity of 0.414 V/Torr in a very fine vacuum regime, while its heating power is less than 21.3 mW. Moreover, the measured output of the micro Pirani gauge shows good agreement with a semi-empirical model, while the model predicts that the proposed Pirani gauge can measure a vacuum pressure as low as $2.6\times 10^{-{4}}$ Torr. The performance achieved by this Pirani vacuum gauge combined with its high level of integration makes it a promising Internet of Things (IoT) sensing node for vacuum monitoring in the industry. [ABSTRACT FROM AUTHOR]

The determination of thermal conductivities for complementary metal–oxide–semiconductor (CMOS) thin-film materials is very important as the operation and failure of integrated circuits (ICs) and CMOS microelectromechanical systems (MEMS) devices are most likely limited by thermal issues, that is, heat transfer. In this article, we present four micro thermal conductivity measurement ($\mu $ TCM) devices for silicon oxide, polysilicon, and aluminum thin films using CMOS MEMS technology. To determine the thermal conductivities of those thin-film materials from the $\mu $ TCM devices, a linear thermal resistance model was proposed and validated by the computational fluid dynamics (CFD) study, which showed an error of less than 5.5%. The thermal conductivities of thin-film materials were then measured over a temperature range of 210–362 K, while the measured results for silicon oxide, polysilicon, and aluminum at room temperature were 1.32, 21.22, and 70.2 W/mK, respectively. Those measured thermal conductivities were significantly smaller than the available bulk values. The discrepancies between the thin film and bulk materials are consistent with the reported data and trends, which reveals the importance of determining the thermal conductivities for thin-film materials in the CMOS MEMS process. [ABSTRACT FROM AUTHOR]