Search

A drive resonance loop of micromachined quartz gyroscope was designed to generate a drive mode resonance based on phase control technology. A velocity amplitude controller was designed to keep the drive oscillation amplitude invariable by a signal amplitude extraction method. The exciting control system was simulated by Matlab Simulink. The simulation results are in good agreement with the design objectives of the resonance loop and the amplitude control system. A drive circuit was fabricated and tested. The results show that the oscillation frequency of the fabricated drive loop is very close to the drive mode frequency. The amplitude controller makes the drive axis to oscillate rapidly and stabilize in half a second. The amplitude of the drive signal is 85 dB higher than the noise at the resonance frequency. [ABSTRACT FROM AUTHOR]

A new high-performance surface-enhanced Raman scattering (SERS) substrate with extremely high SERS activity was produced. This SERS substrate combines the advantages of Au film over nanosphere (AuFON) substrate and Ag nanoparticles (AgNPs). A three order enhancement of SERS was observed when Rhodamine 6G (R6G) was used as a probe molecule to compare the SERS effects of the new substrate and commonly used AuFON substrate. These new SERS substrates can detect R6G down to 1 nM. The new substrate was also utilized to detect melamine, and the limit of detection (LOD) is 1 ppb. A linear relationship was also observed between the SERS intensity at Raman peak 682 cm−1 and the logarithm of melamine concentrations ranging from 10 ppm to 1 ppb. This ultrasensitive SERS substrate is a promising tool for detecting trace chemical molecules because of its simple and effective fabrication procedure, high sensitivity and high reproducibility of the SERS effect. [ABSTRACT FROM AUTHOR]