MEMS-based cantilever infrared detectors: Detection/imaging of infrared radiation is of great importance to a variety of applications ranging from night vision to environmental monitoring, biomedical diagnostics, and remote sensing. Recent advances in MEMS have led to the development of uncooled infrared detector arrays which function bases on bending of bimaterial cantilevers upon absorption of infrared energy. Unfortunately, the manufacturability, planarity and reliability for such cantilever microstructures have been always inadequate. Released devices always bend up (or down) due to the imbalanced residual stresses in the multilayered MEMS structures. Residual stress resulting from thin film fabrication and structure release is the principal source of bent errors in micromachined structures. Stress gradients are particularly troublesome from a detection standpoint, because even relatively small stress variations through the thickness of a thin film can cause significant, undesirable curvatures of the membrane, rendering arrays of devices useless. Our primary focus of this research is on investigating engineering mechanics. We have developed disruptive micromechanics theories and microfabrication technologies, enabling routine manufacturing of low-cost, lightweight, high-performance, cantilever infrared detector arrays for remote sensing.

MEMS-based terahertz metamaterial structures and devices: In collaboration with Prof. Richard Averitt at BU Physics Department, our recent research focuses on creating active structures and devices to enhance our ability manipulate and detect far-infrared, or terahertz, radiation by combining electromagnetic metamaterials with MEMS technologies. Recent advances in metamaterials research have highlighted the possibility to create novel devices with unique electromagnetic functionality. Indeed, the power of metamaterials lies in the fact that it is possible to construct materials with a user-designed electromagnetic response at a precisely controlled target frequency. This is especially important for the technologically relevant terahertz frequency regime with a view toward creating new component technologies to manipulate radiation in this hard to access wavelength range. Motivating our effort to advance terahertz science and technology is the unique characteristics of terahertz radiation which includes transparency to materials such as cardboard, plastic, and styrofoam which are opaque at other wavelengths, and sensitivity to molecular signatures of gas phase and solid phase materials including biological agents and chemical explosives. A potential application is spectroscopic imaging and identification of embedded illicit or hazardous materials. While there have been laboratory-based demonstrations, further improvements in terahertz sources, components, and detectors are required for systems which are sufficiently compact and robust for real-world operation.

Project Examples and Representative Publications

MEMS-based Cantilever Infrared Detectors
MEMS-based Terahertz Metamaterial Structures and Devices

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