Miniaturized optical sensing/imaging technology development for environmental and biomedical applications

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Optical spectroscopy and imaging allow remote, minimally-invasive monitoring of activities; provide morphological information that describes structure/shape; and may be used as a functional diagnostic tool for measuring of biochemical and physiological characteristics. Recent advances of photonics technology are the driving force behind many novel optical devices development. Various optical spectroscopy and imaging technologies have been investigated for applications in life sciences research (e.g. microscopic imaging), environmental sensing (e.g. water quality monitoring) and medical diagnosis (e.g. endoscopic imaging). In practice, there are strong demands for miniaturized, integrated devices for in-situ applications. For example, in screening of cancers in the gastrointestinal (GI) tract, it is highly desired to have encapsulated, functional optical imaging modalities (fluorescence, Raman, etc.) for minimally-invasive detection of malignant lesions. Another example is implantable microfluidic and optical imaging based cellular analysis devices for continuously monitoring of the biochemical and physiological conditions of the patients as well as the environment. Conventional optical spectroscopy and imaging systems are large, complex and costly optoelectronic instruments comprised of lasers, spectrophotometers, and detectors. Often, their size is the limiting factor for their use in certain applications such as in-situ monitoring of physiological processes and distributed environmental sensing. Recent advances in micro-photonics and electronic devices have led to small but efficient components/modules such as diode lasers, single photon avalanche diodes detectors, microlenslets, and GRIN optics. When integrated with microfluidics technology, fully integrated devices can be made by Micro-electro-mechanical-systems (MEMS) or Micro-optical-electro-mechanical-systems (MOEMS). These technologies are mostly built upon well-established microelectronic technologies for integrated circuitry. When conventional devices are replaced with micro-components, new applications and capabilities can be facilitated. Moreover, it usually leads to significant cost reductions and increases in yield associated with mass production. Although progresses have been made recently in the development of individual components such as micro-cantilevers, micro gratings, and micro-lens, etc, integration of these components into complete micro-spectroscopic and imaging devices remains as a very challenging problem. For a complete optical spectroscopic/imaging system, more complex components such as miniature light sources, photo detectors, and high-speed electronics are also required. Furthermore, medical and environmental application of these technologies raises new requirements such as toxicity, chemical/biological stability, and sterilization concerns. The overall objectives of the proposed research program are to (i) develop integrated micro- optical spectroscopic technologies for spectrally- and temporally-resolved optical signal acquisition; (ii) investigate the integration of high speed photo detection modules into the micro-spectrometer; and (iii) development of a fully integrated encapsulated endoscope. The proposed program will be based on the Micro/Nano Systems Lab and focus on integrated device technology development. Its success will allow translation of such technology to applications in biomedical diagnosis, drug discovery, and environmental monitoring.