Dan Seter

A novel micromachined vibrating rate-gyroscope with optical sensing and electrostatic actuation

Abstract This paper reports the fabrication and preliminary characterization of a novel vibratory rate-sensor. The sensor employs the modulated integrative differential optical sensing (MIDOS) to detect the output mode amplitude. The mechanical part of the sensor is fabricated by bulk micromachining using a double side anisotropic wet etching process. A CMOS chip containing the detecting photodiodes and their readout electronics is fabricated through MOSIS. Electrical and mechanical integration of the two parts is achieved by using the indium bumps technology. The proof mass is aligned with the detecting photodiodes, so that when at rest, equal portions of the two photodiodes are exposed. Several prototypes have been fabricated and tested on a rotating table. Good linearity (

Optimal design and noise consideration of micromachined vibrating rate gyroscope with modulated integrative differential optical sensing

A novel design of a micromachined vibrating rate gyroscope is presented. The rate gyroscope consists of a suspended proof mass which is attached by indium bumps to a CMOS chip. The proof mass is excited to vibration by electrostatic force. The displacements due to rate are sensed optically, using CMOS-integrated photodiodes and analog electronics. System considerations, including the mechanical behaviour, optical sensing, electronics, and noise sources of the rate gyroscope, are discussed. An expression for the noise equivalent rate (NER) of the system is obtained in order to derive an optimal design approach for the rate gyroscope. Optimal design and simulations of a case study of a rate gyroscope are presented. The device shows the ability of sensing 1 deg/h even at moderate quality factors of the order of 5000 and low-excitation voltages of 2.25 V.

A generalized algebraic equation for the pull-in condition in micromachined electrostatic micromirrors: modeling and characterization

A new analytical approach for modeling the pull-in condition of voltage controlled electrostatic actuators (VCEA) with a general single degree of freedom (DOF) and general shape is presented. The presented approach gives a more general view of the pull-in condition in electrostatic actuators. The pull-in condition for an electrostatic actuator is defined in the voltage and degree of freedom plane. Then a general algebraic equation, referred to as the pull-in equation, is derived for the actuator. The solution of this equation directly yields the pull-in condition. Several case studies are then presented and their pull-in characteristics are summarized.

Comparative study of novel micromachined accelerometers employing MIDOS

In this paper the fabrication and characterization of a novel implementation of micromachined accelerometers is reported. The accelerometers employ a new sensing technique, the modulated integrative differential optical sensing (MIDOS), to sense the output displacements of their proof-mass. The fabrication process of the hybrid device, which consists a bulk micromachined mechanical part attached by indium bumps to a CMOS chip containing photodetectors and readout electronics, is presented. Several prototypes were fabricated and characterized. The differences between the prototypes are discussed in detail as well as the comparison between their measured characteristics (noise equivalent acceleration (NEA), bandwidth and linearity). The prototypes have demonstrated NEA ranging from 70 [/spl mu/g//spl radic/Hz] to 1 [mg//spl radic/Hz] with bandwidth of 1 kHz to 4 kHz, respectively.

Characterization of a novel micromachined optical vibrating rate gyroscope

The present article presents experimental results measured on a new class of micromachined rate-gyroscope, incorporating integrated optical sensing. A hybrid cantilever type device was fabricated by bulk micromachining, bonded to a complementary metal-oxide-semiconductor chip and encapsulated in a vacuum package. The proof mass is electrostatically actuated and the mechanical output motion is sensed by modulated integrative differential optical sensing method. Characterization of the device, including measurements of the natural frequencies and angular rate, is reported. Noise measurements indicate noise equivalent rate of 10−2–10−3 deg/s/√Hz. Currently the measured minimum detectable rate is 1 deg/s due to experimental setup limitations.