Microsystems, Optoelectronics, & Devices
The small-scale matters, whether it’s small devices to keep workers safe in the field or extending the physical limitations of silicon transistors. ECE researchers work with the materials that make up our technology—developing new devices to improve our world, then making them better, faster, and smaller.
Theresa S. Mayer
Louis J. Guido
Marius K. Orlowski
Mantu K. Hudait
Timothy D. Sands
Guo-Quan (G.Q.) Lu
Inductors and transformers are essential to switch-mode power converters. They are large, heavy, and difficult to integrate in a power converter. Traditional manufacturing often requires pressing, heating, shaping, and winding, which restricts design options. Novel designs that are more efficient (lower loss) and use less magnetic material, such as uniform or constant flux density inductors, are too expensive and take too long to make by traditional means. We have developed a series of magnetic paste materials—both powder-iron and ferrite systems—and used them successfully to make inductors and/or transformers by additive manufacturing. The materials we developed allow for rapid prototyping of novel designs of the magnetic components and ease their integration in power converters.
An ongoing research project involves the design and fabrication of WBG power modules for better thermal dissipation, higher temperature capability, lower parasitics for fast switching, and improved thermo-mechanical reliability.
Current silicon-based CMOS technology is nearing the physical limits of its scaling potential, and increasing data rates pose a challenge to the transmission of electrical signals—while also maintaining low power consumption, low delay, and a high signal-to-noise ratio. Interconnect bottlenecks for inter- and intra-chip communication are projected to be major impediments to energy-efficient performance scaling, thus necessitating optical interconnects com-patible with future CMOS process technologies. Co-integration of electronic and photonic materials and devices with Si manufacturing processes is considered one of the most promising ways to realize the potential of semiconductor compounds. ECE researchers are exploring applications of this integration in optical interconnects, chip-to-chip communication, and low-power and high-speed computing by using cheaper, larger Si wafers. Such monolithic chips will aid and enhance the everyday computing and communication experience for civilian and defense applications.
Resistive switching cell memory, a non-volatile memory based on floating gate MOSFET technology, is a promising technology to supplant current non-volatile memory. In addition to having speed, scalability, density, endurance, and reliability advantages over the current floating gate (FLASH), they do not require silicon substrate. This means they can be stacked in multiple layers in the CMOS metallization, allowing for high densities. They can be placed directly above the logic area, solving the so-called latency problem. ECE researchers are manufacturing the resistive switching devices, and then electrically characterizing them in an effort to understand the basic mechanisms governing their behavior. We are exploring this technology as it ap-plies to memory and neuromorphic applications.
The Microelectromechanical Systems (MEMS) Laboratory at Virginia Tech has been at the forefront of research to develop a field-portable micro gas chromatography system comprising low-power MEMS components including preconcentrators, gas separation columns, and detectors. These systems for on-the-spot analysis of complex gaseous samples, like the air we breathe, can capture analytes even at very low concentrations and then separate and identify the presented compounds through a chromatographic mechanism. We are working on an NSF-funded project to develop Fast Odor Chromatographic Sniffers (FOX-on-chip) that can detect illicit adulteration in food by parallel analysis of the mixture through microfluidic channels and subsequent autonomous data. In line with this project, we are demonstrating the concept of digital chromatography or digital smell. The primary concept is to create electronics signatures (barcodes) for odors (smells) that can be synthesized in a distant location.
Through collaboration with hospitals and bio-medical research communities, we are developing microfluidic channels that can decipher bioelectrical and biomechanical properties of living cells, looking for abnormal cells through alteration in their biophysical signatures. We are analyzing normal and cancerous breast cells, and we find biophysical cues that can be used for early cancer diagnosis or for assessing the efficacy of chemo-therapeutic regimens. We are also investigating the sparsely concentrated circulating tumor cells in the blood of cancer patients through microfluidic constructs with on-chip electrical impedance outputs. Initial results using spiked cancer cells in mouse blood samples have shown the feasibility of our approach.