Eugen I. Cabuz

Factors enhancing the reliability of touch-mode electrostatic actuators

This paper discusses the failure modes frequently encountered in touch-mode electrostatic actuators (TMEA) and reports on practical ways of increasing the time to failure. Humidity is identified as the main source of anomalies in the behavior of TMEA and charge trapping in the dielectric as the main cause of stiction. A method for direct charge measurement is derived and the measurements show good agreement with the calculated data. A new driving scheme is proposed that, together with surface treatments based on self-assembled monolayer, desensitizes the actuator to environmental conditions. In this way, actuators working without failure in room air for over 40 million cycles were obtained.

Development of a MEMS gyroscope for northfinding applications

We report progress toward a MEMS gyroscope suitable for northfinding in pointing and targeting applications. In-run bias stability of 0.03 deg/hr and ARW of 0.002 deg/rt(hr) have been achieved. Gyro performance was measured on tuning-fork type MEMS gyroscopes using DSP-based breadboard electronics. These bias stability and ARW results are within about 6X and 2X, respectively, of meeting the typical gyrocompass requirements for pointing and targeting applications (1 milliradian azimuth precision at 65 degrees latitude with 5 minute integration time). A MEMS gyrocompass meeting these requirements would substantially reduce the size, weight and power of pointing and targeting instruments. The test methodology will be presented, as well as test data on carouseling the sensor to reduce the effects of long-term bias drift.

A MEMS-based correlation radiometer

We describe the development of a MEMS-based correlation radiometer for remote detection of chemical species. The radiometer utilizes a new type of MEMS programmable diffraction grating called the Polychromator. The Polychromator contains an array of 1024 electrostatically actuated reflective beams that are 10 microns wide by 1 cm long, and have a vertical travel of approximately 2 - 4 microns. The Polychromator grating is used to replace the reference cell of conventional correlation radiometry. Appropriate programming of the deflection profile of the grating array enables the production of any spectral transfer function desired for the correlation measurement. Advantages of this approach to correlation radiometry include the ability to detect multiple chemical species with a compact instrument, the ability to optimize the reference spectra to eliminate chemical interferences, and the ability to produce reference spectra for hazardous and transient species.

Toroidal resonators with small frequency mismatch for rate integrating gyroscopes

This paper reports an order of magnitude reduction in frequency mismatch (ΔF) in polycrystalline diamond half-toroid resonators under development for use as microscale rate-integrating gyroscopes. The reduction in ΔF was achieved by eliminating the lip at the perimeter of the resonator. Measurements of resonance decay time as a function of frequency, temperature, and pressure are also reported.