David A. Horsley (Advisor)

Research Advised by Professor David A. Horsley

BPN539: Micromechanically-Enhanced Magnetoresistive Sensors

Gerardo Jaramillo
Andre Guedes

Magnetoresistive (MR) sensors are highly sensitive magnetic field sensors but suffer from large 1/f noise. We have developed a new approach for reducing the 1/f noise in MR sensors by using a MEMS resonator to mechanically modulate the magnetic field signal to a high frequency, where the 1/f noise vanishes. This mechanism improves the MR element sensitivity by 2-3 orders of magnitude in the low frequency sensing range. A fully integrated fabrication process was developed, where the MR sensor is fabricated first on the surface of a SOI wafer and the MEMS actuators are fabricated last...

BPN656: Airborne Particulate Monitoring Using a Micromechanical Electrometer

Gerardo Jaramillo

Environmental air quality is monitored by accurately sizing and quantifying nanometer-sized aerosol particles present in the atmosphere. One method of detection electrically charges the particles and then feeds a stream of charged particles into a Faraday cup electrometer. We present the first results of a MEMS based electrometer for the detection of small currents from ionized particles in a particle detection system.

Project end date: 08/12/13

BPN642: 10 MHz Optical Phased Array Metrology and Control

Mischa Megens

Very fast optical beam steering and wave front correction can be achieved by employing phased arrays of lightweight High Contrast Grating (HCG) MEMS mirror etalons. The etalons provide a large phase shift for a small displacement, 100x more than traditional reflective mirror elements. Operating such etalon arrays requires exquisite control of the MEMS mirror displacements. Our aim is to use in-situ stroboscopic interferometric imaging of the etalons to ensure phase accuracy and combat long term-drift, while employing feed-forward electrical input shaping to achieve fast settling time...

BPN645: Highly-Parallel Magnetically-Actuated Microvalves

Pauline J. Chang

This project aims to develop highly-parallel, magnetically-actuated microvalves using CMOS- compatible technology. Current state-of-the-art microvalve technologies require extensive supporting experimental apparatus and do not yield true lab-on-a-chip functionality. Here, the focus is placed on true chip-scale valve arrays based on low-power, on-chip magnetic coils which are used to actuate 100 micron diameter magnetic spheres that serve as the valve sealing surface. Prior studies of magnetic bead manipulation by planar coils, spin-valve arrays, and rotating magnetic fields have...

BPN595: Fast Optical Phased Array for 10MHz Beamforming

Mischa Megens

We developed an optical phased array incorporating a single-layer high-index-contrast sub- wavelength grating (HCG) for 2D beamsteering. There are a number of other approaches for optical phased arrays such as liquid-crystal-based phased arrays and microelectromechanical system (MEMS) phased array. Switching of liquid-crystal based phased arrays typically takes on the order of milliseconds. Arrays of MEMS mirrors moving perpendicular to the substrate are usually made of silicon so that a metal-coated layer is required on top, resulting in thermal induced stress when very high optical...

BPN655: Materials for High Quality-Factor Resonating Gyroscopes

Hadi Najar
Chen Yang

This project will investigate new materials suitable for achieving Q-factors in excess of 1 million in resonating gyroscopes. Experimental studies of dissipation caused by thermoelastic and surface losses will be performed using resonator test structures. The effect of doping and microstructure is explored on CVD diamond MEMS resonators. Hundreds of surface micromachined cantilevers and double-ended tuning fork (DETF) resonators were fabricated in nanocrystalline diamond (NCD) and microcrystalline diamond (MCD) films deposited using hot filament CVD technique with varying levels of...

BPN684: Integrated Microgyroscopes with Improved Scale-Factor and Bias Stability

Jason Su

Despite their small size, low power dissipation, and low cost, the large bias and scale factor errors of current MEMS inertial sensors preclude using them for dead reckoning navigation. Although these shortcomings can be overcome with precision manufacturing and extensive calibration, such solutions suffer from high cost and secondary effects such as long term drift. Presently, the use of in-situ calibration techniques in MEMS sensors is limited to the electronic interfaces, where they are instrumental for reducing drift arising from electronic components. This project extends the...

BPN781: 3-Axis MEMS Gyroscope

Soner Sonmezoglu
Parsa Taheri-Tehrani

The goal of the project is to design the resonator and electronics for a single structure 3-Axis MEMS vibratory rate gyroscope. The mechanical structure of the device will be designed to have the capability of 3-Axis sensing performance. Low-power CMOS electronics will be designed to meet the requirements for consumer electronics.

Project end date: 01/31/16

BPN722: 3D Ultrasonic Fingerprint Sensor On a Chip Using Piezoelectric Micromachined Ultrasonic Transducers (PMUT)

Joshua Kay
Joy Jiang

We've successfully built a 500dpi, 4.75mm x 3.5mm monolithic ultrasonic fingerprint sensor on a chip with PMUT and integrated CMOS process that solves the problem of capacitive fingerprint sensors. The sensor is resilient to common contamination such as dirt, sweat, and oil by penetrating through them, and the sensor has the capability of capturing inner-finger feature such as dermis fingerprint. The capability of generating a three- dimensional, volumetric image of the finger surface and the tissues beneath the finger surface makes it extremely difficult to deceive the sensor with...

BPN466: Air-Coupled Piezoelectric Micromachined Ultrasonic Transducers

Scott Block

Characterize air-coupled aluminum nitride piezoelectric micromachined ultrasound transducers (pMUTs) for use in range finding and gesture recognition applications. MEMS Aluminum Nitride (AlN) piezoelectric sensor technology has been chosen due to the relatively simple deposition process and compatibility with CMOS technology which enables the potential integration of the sensor and drive electronics on the same chip. Guided by both analytic and finite element models the optimum design parameters are chosen to obtain the desired resonant frequency, bandwidth, and maximum output sound...