Wireless MEMS-Based Strain Sensing Microsystem

Professor Darrin Young

Electrical and Computer Engineering Department

The University of Utah

Abstract

Advancement in micromachined sensors, actuators, and low-power integrated electronics has fueled recent rapid development in wireless microsystem technology providing autonomous sensing and communication capability. Ultra low system power dissipation allows batteryless microsystem to be achieved with a small form factor and powered by ambient or external energy sources. Such system is crucial for biomedical as well as industrial sensing applications, where size, weight, and limited access are critical system design constraints. Optimized design in system, device, circuit, and packaging is highly important for achieving an overall high performance. In this seminar, I will present a high-performance MEMS-based strain sensing microsystem consisting of sensors and interface electronics for advanced industrial applications. A MEMS capacitive strain sensor converts an input strain to a capacitance change with a sensitivity of 26.5 aF per 0.1 me. Low-noise integrated sensing electronics employing a continuous time synchronous detection architecture convert the capacitive signal to an output voltage followed by a 2^nd-order ΣΔ ADC. An RF-to-DC converter based on inductive coupled coils converts a 50 MHz AC signal to a stable DC supply of 2.8V with a current driving capability of 2 mA, sufficient to power the microsystem. A two-channel digital phase shift keying (PSK) and amplitude shift keying (LSK) passive telemetry achieve a wireless data transmission rate of 2.56 Mbps and 128 kbps, respectively, which are adequate for sending the strain data and temperature information for thermal compensation. The prototype microsystem achieves a minimum detectable strain of 0.5 ne/  with a maximum input strain of +/-1000 me.

Darrin Young’s Biography

Darrin J. Young received his B.S., M.S., and Ph.D. degrees from the Department of Electrical Engineering and Computer Sciences at University of California at Berkeley in 1991, 1993, and 1999, respectively. He pioneered the research work in MEMS-based, high-Q, tunable capacitors and on-chip 3-D coil inductors for low-phase noise RF voltage-controlled oscillator (VCO) design for wireless communication applications. His doctoral thesis work demonstrated the first RF-CMOS VCO employing on-chip high-Q passive devices achieving the stringent GSM phase noise requirements. Between 1991 and 1993, he worked at Hewlett-Packard Laboratories in Palo Alto, California, where he designed a shared memory system for a DSP-based multiprocessor architecture. Between 1997 and 1998, he worked at Rockwell Semiconductor Systems in Newport Beach, California, where he designed silicon bipolar RF analog circuits for cellular telephony applications. During this time period he was also at Lawrence Livermore National Laboratory, working on the design and fabrication of three-dimensional RF MEMS coil inductors for wireless communications. Dr. Young joined the Department of Electrical Engineering and Computer Science at Case Western Reserve University in 1999 as an assistant professor. In 2009 he joined the Electrical and Computer Engineering Department at the University of Utah as an USTAR associate professor. His research interests include micro-electro-mechanical systems design, fabrication, and integrated analog circuits design for wireless sensing, biomedical implant, communication, and general industrial applications. He has published many technical papers in journals and conferences, and served as a technical program committee member and session chair for a number of international conferences. Dr. Young is also an associate editor of the IEEE Journal of Solid-State Circuits.