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Welcome to the website of Professor Farrokh Ayazi's research group in the School of Electrical and Computer Engineering at the Georgia Institute of Technology. Research in the Integrated MEMS Laboratory relates to the design, analysis, fabrication, and characterization of Micro and Nano Electro-Mechanical Systems (MEMS and NEMS), with a focus on high Q resonators and resonant gyroscopes. High Q resonators have applications in 'mixed-domain microsystems' such as gyroscopes and accelerometers, low jitter clocks, energy harvesters, biochemical sensors for health and environmental monitoring, as well as wireless communications. On the system side, the group specializes on advance interface circuits and architectures for MEMS and Sensors. 

Mechano-acoustic signals emanating from the heart and lungs contain valuable information about the cardiopulmonary system. Unobtrusive wearable sensors capable of monitoring these signals longitudinally can detect early pathological signatures. Above, we present a wearable, hermetically-sealed high-precision vibration sensor that combines the characteristics of an accelerometer and a contact microphone to acquire wideband mechano-acoustic physiological signals, and enable simultaneous monitoring of multiple health factors associated with the cardiopulmonary system including heart and respiratory rate, heart sounds, lung sounds, and body motion and position of an individual. 

We have developed an encapsulated accelerometer contact microphone (ACM) that utilizes nano-gap transducers to achieve extraordinary sensitivity in a wide bandwidth (DC-12 kHz) with high dynamic range. The sensors were used to obtain health factors of six control subjects with varying body mass index, and their feasibility in detection of weak mechano-acoustic signals such as pathological heart sounds and shallow breathing patterns is evaluated on patients with preexisting conditions.

Link to research article: npj Digital Medicine

Open Postdoctoral Fellow Position

A postdoctoral fellow position is available immediately at the Integrated MEMS Laboratory in the area of ultra-high-Q acoustic resonators and hybrid MEMS and Quantum Systems in mono-crystalline silicon carbide (SiC).  Interested individuals should submit their CV and statement to Prof. Ayazi’s attention at ayazi@gatech.edu

New Publication Alert
 

Investigating Elastic Anisotropy of 4H-SiC Using Ultra-High Q Bulk Acoustic Wave Resonators

Jeremy Yang , Benoit Hamelin , and Farrokh Ayazi

Journal of Microelectromechanical Systems, (2020), doi: 10.1109/JMEMS.2020.3022765.

Hexagonal 4H-silicon carbide (4H-SiC) is a transversely isotropic substrate garnering interest for precision MEMS devices such as resonant gyroscopes. This paper investigates the elastic anisotropy of 4H-SiC by utilizing capacitive bulk acoustic wave (BAW) resonators with ultra-high mechanical quality factors (Q) enabled by phononic crystals. We directly measure the value of C66 using Lamé mode resonators for the first time and numerically fit the values of C11 and C12 using BAW elliptical modes in center-supported solid disk resonators. We compare (0 0 0 1) 4H-SiC to (1 1 1) Si, another in-plane isotropic material and validate (0 0 0 1) 4H-SiC’s superior robustness to fabrication and design variations. Measurement of in-plane BAW elliptical modes in multiple disk resonators with as-born frequency splits as low as 3 ppm reveal (0 0 0 1)4H-SiC’s transverse isotropy across process corners. Lamé mode resonators display a temperature coefficient of frequency (TCF) three times lower compared to its Si counterpart. Finally, this paper provides a modified set of elastic constants for 4H-SiC with a view towards monocrystalline

Link to research article: Journal of Microelectromechanical Systems