A microarray with a period of about 1 μm was fabricated from a crosslinked liquid crystal polymer (CLCP) containing azobenzene groups by using the replica molding technique. In accordance with the photoinduced deformation of the CLCP induced by the photoisomerization of the azobenzene groups, on-off switch behavior on the reflection spectra of the microarray was observed by alternate irradiation with UV-Vis light. The reversible switch behavior indicates that the azobenzene CLCP microarray has potential applications in optical actuators.
This paper reports a nano-opto-mechanical pressure sensor based on nano-scaled ring resonator. The pressure is measured through the output spectrum shift which is induced via mechanical deformation of the ring resonator. The sensitivity as high as 1.47 pm/kPa has been experimentally achieved which agrees with numerical prediction. Due to the strong variation of sensitivity with different ring radius and thickness of the diaphragm, the pressure sensor can be used to form an array structure to detect the pressure distribution in highly accurate measurement with low-cost advantages. The nano-opto-mechanical pressure sensor has potential applications such as shear stress displacement detection, pressure wave detector and pressure mapping etc.
Highly sensitive and selective hydrogen sulfide (H2S) sensors based on hierarchical highly ordered SnO2 nanobowl branched ZnO nanowires (NWs) were synthesized via a sequential process combining hard template processing, atomic-layer deposition, and hydrothermal processing. The hierarchical sensing materials were prepared in situ on microelectromechanical systems, which are expected to achieve high-performance gas sensors with superior sensitivity, long-term stability and repeatability, as well as low power consumption. Specifically, the hierarchical nanobowl SnO2@ZnO NW sensor displayed a high sensitivity of 6.24, a fast response and recovery speed (i.e., 14 s and 39 s, respectively), and an excellent selectivity when detecting 1 ppm H2S at 250 °C, whose rate of resistance change (i.e., 5.24) is 2.6 times higher than that of the pristine SnO2 nanobowl sensor. The improved sensing performance could be attributed to the increased specific surface area, the formation of heterojunctions and homojunctions, as well as the additional reaction between ZnO and H2S, which were confirmed by electrochemical characterization and band alignment analysis. Moreover, the well-structured hierarchical sensors maintained stable performance after a month, suggesting excellent stability and repeatability. In summary, such well-designed hierarchical highly ordered nanobowl SnO2@ZnO NW gas sensors demonstrate favorable potential for enhanced sensitive and selective H2S detection with long-term stability and repeatability.
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