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A novel structure of the resonant pressure sensor is presented in this paper, which tactfully employs intercoupling between dual pressure-sensing diaphragms and a laterally driven resonant strain gauge. After the resonant pressure sensor principle is introduced, the coupling mechanism of the diaphragms and resonator is analyzed and the frequency equation of the resonator based on the triangle geometry theory is developed for this new coupling structure. The finite element (FE) simulation results match the theoretical analysis over the full scale of the device. This pressure sensor was first fabricated by dry/wet etching and thermal silicon bonding, followed by vacuum-packaging using anodic bonding technology. The test maximum error of the fabricated sensor is 0.0310%F.S. (full scale) in the range of 30 to 190 kPa, its pressure sensitivity is negative and exceeding 8 Hz/kPa, and its Q-factor reaches 20,000 after wafer vacuum-packaging. A novel resonant pressure sensor with high accuracy is presented in this paper.

Micro‐nanofabrication technologies are frequently used to prepare surface‐enhanced Raman scattering (SERS)‐active substrates with specially shaped microstructures, whose characteristics of high sensitivity and good reproducibility are our unswerving pursuit of the goal. However, these techniques suffer from high cost and low throughput, which limits the fabrication of large‐area SERS substrates and restricts their practical application in detection analysis. Therefore, a low‐cost, facile, and environmentally friendly fabrication strategy for SERS‐active substrates by sonochemical treatment in conjunction with mechanical stirring without surfactants is proposed for the detection of low concentrations of molecules. Liquid metal alloys were employed as SERS‐active substrate materials and are easily oxidized to form an oxide film in air, resulting in good dispersion of the nanoparticles. In addition, nanograss consisting of rod‐like structures and nanogaps formed on the micro/nanoparticle surface, providing numerous SERS‐active sites. The shape, size, and surface nanostructure of the micro/nanoparticles could be tuned by controlling the ultrasonication time and the stirring speed. The performance of the SERS substrate coated with Au film was evaluated by using rhodamine 6G as a probe. The resulting limit of rhodamine 6G detection for the optimized nanograss‐structured substrate by Raman analysis was as low as 10−7 M, and the standard deviation was 8–15.5%, which meets the requirements for the trace detection of analytes. This facile, large‐scale, low‐cost, and green synthesis of a liquid metal nanograss‐structured substrate with high SERS activity and sensitivity makes it a perfect choice for practical SERS detection applications.

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3D printing technique for microfluidics provides a rapid and cost-effective manufacturing method in one step without considering the complex three-dimensional structures. Because of the layer-by-layer printing process, the microchannel was characterized with rough surface while lacking research on it. Currently, the surface roughness of microchannels is improved mainly by etching (solvent vapor or wet chemical etching), which has two disadvantages: material selectivity and channel openness. In this study, the Polydimethylsiloxane (PDMS) coating method was employed to improve the surface quality of 3D printed microchannels to address the problems mentioned above. The adhesion strength of PDMS on 3D printed substrate was tested. The method proposed in this paper not only reduced the surface roughness of the microchannel effectively (40 fold for circular microchannels) but also reduced the pressure drop of the PDMS coated microchannel by 63.7% and reduced the leakage rate of the 3D printed microvalve by 67%. Moreover, cell viability was tested to validate the feasibility of the method for biomedical and cell analysis applications. Due to the good adhesion properties of PDMS to most materials used in microfluidics, the surface treatment method proposed in this paper can be expanded to other rapid fabrication techniques for low-cost and high-quality microfluidics.