Toward a Miniaturized Wireless Fluorescence-Based Diagnostic Imaging System

Abstract

Fluorescence based spectroscopy and imaging techniques provide qualitative and quantitative diagnostic information about biological systems. Some tissue cells have inherent fluorescence characteristics, and when excited with light at a certain frequency, they can emit light of a slightly longer wavelength; a phenomenon known as autofluorescence. Differences in the autofluorescence emission spectra between healthy and diseased tissue may be used as a non-invasive diagnostic tool for the detection of diseases. In this thesis, I describe the design, fabrication, and testing of a miniaturized fluorescence imaging device for non-invasive clinical diagnosis in the gastrointestinal tract. The device is designed such that it can be turned completely wireless. The system includes three sub-modules: optical imaging, electronics control and image acquisition, and information processing and transmission. These modules were individually developed and tested before being integrated into a complete, externally powered device. The final integrated system is small in size (diameter: ~ 2.5 cm; length: ~ 11 cm). The performance of each individual module and the overall integrated system has been evaluated using fluorescent phantoms. It has been demonstrated that the miniaturized device can acquire spectrally-resolved fluorescence images. It has also been separately demonstrated that the image stream can be transmitted wirelessly. An important outcome of this feasibility study is the identification of important technological issues and pathways for future prototype development.