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The paper introduces a SU-8 dielectric µ-bridge based polymer MEMS Pirani gauge which can be employed for hermetic characterization of packaged electronic sensors. The µ-bridge structure is adopted due to its simplicity in fabrication and lower footprint, which makes it feasible for heterogeneous integration. Further, the integration of SU-8 polymer with the active thermistor offers superior thermal isolation from the substrate and extends the dynamic range. Before fabricating the actual device, the SU-8 based µ-bridge is optimized for stress-free release. A stress engineering is performed and thermal processing of SU-8 is optimized. The measurement results reveal that the removal of quenching from the baking steps leads to the successful fabrication of freely suspended µ-bridge with SU-8 polymer as a structural layer. A quantitative comparison of the proposed gauge is established by comparing the gauge performance with conventional dielectric materials like silicon dioxide (SiO2), silicon nitride (Si3N4), and aluminum oxide (Al2O3). The fabricated SU-8 polymer-based MEMS Pirani gauge with a 40 µm × 7 µm footprint can be used for hermetic characterization from 30 Pa to 105 Pa and is an ideal candidate for heterogeneous integration.

The presence of metal particles in lubricating oil produced during the wear and tear of mechanical equipment can harm its performance severely if not detected in time. Hence, the detection of such particles is necessary to predict and to prevent disastrous failures of the machines. This paper presents a new non-contact cross-capacitive sensor for the detection of metal particles in the lubricating oil. The sensor can detect each and every metal debris particle in the lubricating oil by monitoring the capacitance peak. The proposed capacitive sensor works on the principle of the Thompson–Lampard theorem. The sensor consists of four cylindrical electrodes with infinitesimal gaps wrapped around a hollow Teflon tube. The sensor has been modeled with finite element simulation software and then fabricated to verify the theory experimentally. Experimental results show that the capacitance value shows a sharp change in its value due to the presence of metal debris in the oil. The output of the sensor is highly precise (±0.82%) and accurate.

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