Joseph Talghader

My group works in the areas of optics and micro-/nano-mechanical systems. One of our focus areas is infrared detectors. Standard uncooled detectors are designed for extreme sensitivity across the thermal infrared, but they are inappropriate for imaging high temperature regions or specific wavelength ranges. Some of our recent research has developed new ways to control the responsivity and sensing wavelengths of these detectors to accommodate these applications.

Other areas are optical coatings and heat transfer for both micro and large-scale optics. Two of the biggest challenges in optical microsystems are building devices with adequate heat conduction and integrating optical coatings that do not cause warping due to stress and thermal expansion. Some of our recent results include making stress and thermal expansion invariant coatings and negative thermal expansion thin films for matching zero expansion glasses. These projects are leading to adaptive mirrors with high heat transfer and coatings for lightweight mirrors and high power lasers.

My group is also interested in the thermal and thermoelectric properties of contact interfaces. In microfabricated systems, the roughness of contact interfaces is often on the order of a nanometer or less, which makes their behavior much different from traditional interfaces with larger roughness. With proper design and control, micromachined interfaces may have enhanced thermoelectric properties, enabling highly efficient cooling and power generation.

A final research interest lies with microsensors. A great deal of sensor research involves creating intelligent sensors that can work in a distributed network; however, there are many applications where extremely simple sensors are more appropriate. One technology on which we are working removes all processing and communication capabilities from the sensors and uses self-assembly to read out sensor data after collection. This type of sensor is particularly well suited for fluidic systems and the first devices are being applied to metal-ion detection.

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