Chemical vapor deposition graphene (CVDG) and electrochemical exfoliated graphene (ECG) were transferred and spin-coated on the nanoporous alumina substrate (NS) and flat alumina substrate (FS) to investigate the effect of substrate topography for graphene-based humidity sensors. The electrical resistance change of two graphene types on different substrate topography could be measured to estimate the environmental relative humidity. The relationship between graphene types, substrate topography, wettability, and humidity sensing performance was studied and discussed. The results of the water contact angle of CVDG on NS/FS and ECG on NS/FS were 77.0 ± 5.0°, 88.8 ± 4.9°, 55.9 ± 7.0°, and 59.8 ± 3.2°, respectively. The response, linearity and hysteresis characteristics of four graphene-based humidity sensors were measured and estimated. The ECG on NS humidity sensor shows the best performance in regards to the response, linearity and hysteresis.

In this work, an electrostatic comb-drive micro-mirror with the Pd-based metallic glass torsion bar and the self-aligned structures was proposed and developed. The self-aligned structure of the comb-drive micro-mirror is achieved avoiding the comb structure alignment process. The fixed combs of the top mirror wafer were lifted by the bottom activation post for making the comb height difference. The height difference between the fixed combs and moving combs could effectively increase the torque to the mirror structure. The static tilting angle of 16° was achieved when the input voltage is 45.6 V. In the resonant mode, the scanning angle of 40.5° was achieved when the input voltage is 30 Vpp at 95 Hz. According to the measurement results and comparing with other silicon torsion bar micro-mirrors, the driving voltage could be decreased 50% and the tilting angle could be increased around four times for the proposed micro-mirror.