2008 NSTI Nanotechnology Conference and Trade Show - Nanotech 2008 - 11th Annual

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TechConnect Summit
Clean Technology 2008

A Novel Uncooled IR Imaging Micro-Cantilever Pixel Bimaterial Structure with Optical Interferometric Readout

B. Sun
cape peninsula University of technology, ZA

Keywords:
uncooled IR imaging, micro-cantilever pixel, bimaterial structure, optical interferometric readout

Abstract:
Infrared imaging sensors that operate without cryogenic cooling have the great potential to provide commercial and military users with exceptional night vision capabilities. Considerable progress has been made in recent years reducing the pixel size while improving the imaging sensitivity by using micro-cantilever type structure technology. A micro-cantilever based sensor can detect extremely small external stimuli that include temperature and surface stress changes. It has been successfully applied to thermal and infrared sensing. In all these cases, the cantilever produced either a static or its resonance frequency changes. Deflection sensing methods can be divided into two categories: electrical and optical. Although the electrical method, including capacitance and piezo-resistive sensing, is promising due to its compatibility with electric signal processing, it is limited due to lack of thermal isolation and Johnson noise. Furthermore, for piezo-resistive sensing, there are technological limits in fabricating a thin, highly sensitive cantilever. The most common readout techniques for cantilever motion are optical including optical lever and interferometric methods. These optical methods can detect cantilever motion with sub-Angstrom resolution limited only by thermal vibration noise. In this presentation, we propose a novel uncooled IR imaging micro-cantilever pixel bimaterial structure (MCPBS) based on the structure invested by ORNL and Multispectral Imaging Inc.The proposed MCPBS is a thermal compensation structure and has nulling out any substrate temperature induced motion in the cantilever paddle. The new deflection induced by the temperature change has been modified by taking into account of the length of the paddle. The measurement of the deflection will be sensed by an ineterferometric optical readout. The analytical relationship between interferometric intensity I(t) and the temperature change T has been derived for the first time by using Fourier series. The relationship has taken into account the dynamical response of structure due to the change of the temperature change T.


Nanotech 2008 Conference Program Abstract