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This paper describes the first precision 32kHz low-power MEMS-based oscillator in production. The primary goal is to provide a small form-factor oscillator (1.5 x 0.8 mm 2) for use as a crystal replacement in space-constrained mobile devices. The oscillator generates an output frequency of 32.768kHz and its binary divisors down to 1Hz. The frequency stability over the industrial temperature range (-40°C to 85°C) is ±100ppm as an oscillator (XO) or ±3ppm with optional calibration as a temperature compensated oscillator (TCXO). Supply currents are 0.9µA for the XO and 1.0µA for the TCXO at supply voltages from 1.4V to 4.5V. The MEMS resonator is a capacitively-transduced tuning fork at 524kHz. The circuitry is fabricated in 180-nm CMOS and includes low power sustaining circuit, fractional-N PLL, temperature sensor, digital control, and low swing driver.

A high-density GaN nanowire array has been successfully fabricated through self-organized nanometer-sized holes as mask appearing in InGaN layer. The self-organized nanometer-sized holes are naturally formed during InGaN epitaxial growth using metalorganic chemical vapor deposition technology by modifying growth parameters. Scanning electron microcopy and atomic force microcopy have been used to characterize them. Optical investigation was carried out by room-temperature photoluminescence, which indicated that strong emission from an n-GaN nanowire array was observed at 367 nm, the near-band edge emission wavelength for n-type GaN. The results show that excellent optical properties of the GaN nanowire array can be obtained by this technique. It is important to point out that GaN-based nanolaser or nano-light-emitting diodes with different emission wavelengths can be potentially achieved using this technology.

We investigated the effects of orientation angle on the adhesion of single gecko setae using dual-axis microelectromechanical systems force sensors to simultaneously detect normal and shear force components. Adhesion was highly sensitive to the pitch angle between the substrate and the seta's stalk. Maximum lateral adhesive force was observed with the stalk parallel to the substrate, and adhesion decreased smoothly with increasing pitch. The roll orientation angle only needed to be roughly correct with the spatular tuft of the seta oriented grossly towards the substrate for high adhesion. Also, detailed measurements were made to control for the effect of normal preload forces. Higher normal preload forces caused modest enhancement of the observed lateral adhesive force, provided that adequate contact was made between the seta and the substrate. These results should be useful in the design and manufacture of gecko-inspired synthetic adhesives with anisotropic properties, an area of substantial recent research efforts.