Advanced single-chip temperature stabilization system for silicon MEMS resonators and gyroscopes

The main objective of this research is to develop temperature and frequency stabilization techniques for silicon MEMS oven-controlled crystal oscillators (MEMS OCXO) with high-frequency stability. The device was built upon an ovenized platform that used a micro-heater to adjust the temperature of the resonator. Structural resistance-based (Rstruc) temperature sensing was used to improve the self-temperature monitoring accuracy of the silicon MEMS resonator. An analog feedback micro-oven control loop and a feedforward digital calibration scheme were developed for a 77MHz MEMS oscillator, which achieved a ±0.3ppm frequency stability from -25°C to 85°C. An AC heating scheme was also developed to enable tighter integration of the resonator, temperature sensor (Rstruc) and heaters. This temperature stabilization technique was also applied to silicon MEMS mode-matched vibratory x/y-axis and z-axis gyroscopes on a single chip. The temperature-induced frequency change, scale factor and output bias variations were all reduced significantly. The complete interface circuit for the single-chip three axes gyroscopes were also developed with an innovative trans-impedance amplifier to reduce the input-referred noise. For the first time, the simultaneous operation of mode-matched vibratory 3-axis MEMS gyroscopes on a single chip was demonstrated.Ph.D

Metamaterial

In-depth analysis of the theory, properties and description of the most potential technological applications of metamaterials for the realization of novel devices such as subwavelength lenses, invisibility cloaks, dipole and reflector antennas, high frequency telecommunications, new designs of bandpass filters, absorbers and concentrators of EM waves etc. In order to create a new devices it is necessary to know the main electrodynamical characteristics of metamaterial structures on the basis of which the device is supposed to be created. The electromagnetic wave scattering surfaces built with metamaterials are primarily based on the ability of metamaterials to control the surrounded electromagnetic fields by varying their permeability and permittivity characteristics. The book covers some solutions for microwave wavelength scales as well as exploitation of nanoscale EM wavelength such as visible specter using recent advances of nanotechnology, for instance in the field of nanowires, nanopolymers, carbon nanotubes and graphene. Metamaterial is suitable for scholars from extremely large scientific domain and therefore given to engineers, scientists, graduates and other interested professionals from photonics to nanoscience and from material science to antenna engineering as a comprehensive reference on this artificial materials of tomorrow

A liquid-in-glass thermometer with sub-microKelvin resolution, and its application for calorimetry

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (p. 95-104).Labeling methods with optical readout are widely used to implement high throughput screens for drug discovery. However, labeling requires assay customization and does not allow examination of the reactants in their native state. The most direct and universal non-labeling method is calorimetry, but current calorimetric techniques are limited in resolution and throughput for pharmaceutical applications. In this thesis, a novel single-reaction microcalorimeter with optical readout, based on liquid expansion, was designed and built. The instrument was first constructed as a miniature liquid-in-glass thermometer in which the meniscus level was read by a Michelson interferometer. Contact angle hysteresis was limited by a wetting film and the low meniscus velocity. The sub-microKelvin resolution achieved was the lowest known for any thermometer above cryogenic temperatures. The thermometer was modified for use as a batch analysis microcalorimeter. Special attention was paid to minimize evaporation of the 1 /L reaction drops. Resolution of approximately 10 pJ was achieved for an acid dilution.by Robert David.Ph.D