Microfluidic discharge-based optical sources for detection of biochemicals.

This paper reports a discharge-based optical source for fluorescence of biochemicals in microfluidic systems. Its efficacy is demonstrated using a stacked microchip that integrates a microfluidic wavelength-tunable optical source, a biochemical sample reservoir and optical filters. It is shown to excite fluorescence in l-tryptophan and DNA samples labeled by SYBR green dye. The discharge is struck in ambient air, between a metal anode and a cathode cavity that is filled with an aqueous solution, which is doped with a metal salt selected for its emission characteristics. The characteristic line spectra, which arise from energetic transitions of the metal ions that are sputtered into the glow region of the discharge, are optically filtered and guided to the biochemical sample that resides in a separate on-chip reservoir. For DNA fluorescence, a barium chloride solution is used to emit light at 454 and 493 nm. For tryptophan fluorescence, the cathode contains lead (ii) nitrate solution to provide a 280 nm emission. The resulting fluorescence from the DNA and tryptophan samples is compared to reference data. This technique can also be used to excite other fluorophores by using appropriately doped liquid cathodes having the desired emission characteristics.

[1]  L. H. Light,et al.  Transistor d.c. convertors , 1955 .

[2]  James S. Speck,et al.  Growth and fabrication of short-wavelength UV LEDs , 2004, SPIE Optics + Photonics.

[3]  C H Mastrangelo,et al.  Monolithic capillary electrophoresis device with integrated fluorescence detector. , 2001, Analytical chemistry.

[4]  William C. Sweatt,et al.  Integrated micro-optical fluorescence detection system for microfluidic electrochromatography , 1999, Photonics West - Micro and Nano Fabricated Electromechanical and Optical Components.

[5]  Y. Gianchandani,et al.  A microfluidic ultra-violet emission source for direct fluorescence of tryptophan , 2003, Proceedings of the 25th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (IEEE Cat. No.03CH37439).

[6]  Y. Gianchandani,et al.  Spectral detection of metal contaminants in water using an on-chip microglow discharge , 2002 .

[7]  J. Lakowicz,et al.  Fluorescence lifetime imaging of free and protein-bound NADH. , 1992, Proceedings of the National Academy of Sciences of the United States of America.

[8]  Alexey S. Ladokhin,et al.  Fluorescence Spectroscopy in Peptide and Protein Analysis , 2006 .

[9]  Robert Kaplar,et al.  Room-temperature direct current operation of 290 nm light-emitting diodes with milliwatt power levels , 2004 .

[10]  Chester G. Wilson,et al.  Profiling and modeling of dc nitrogen microplasmas , 2003 .

[11]  J. Hopwood,et al.  A microfabricated inductively coupled plasma generator , 2000, Journal of Microelectromechanical Systems.

[13]  Y. Gianchandani,et al.  Microfluidic electrodischarge devices with integrated dispersion optics for spectral analysis of water impurities , 2005, Journal of Microelectromechanical Systems.

[14]  S. Clark,et al.  High-sensitivity capillary electrophoresis of double-stranded DNA fragments using monomeric and dimeric fluorescent intercalating dyes. , 1994, Analytical chemistry.

[15]  A Scherer,et al.  A microfabricated device for sizing and sorting DNA molecules. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[16]  J.S. Harris,et al.  Integrated semiconductor fluorescent detection system for biochip and biomedical applications , 2002, 2nd Annual International IEEE-EMBS Special Topic Conference on Microtechnologies in Medicine and Biology. Proceedings (Cat. No.02EX578).

[17]  Raymond F. Chen,et al.  Measurements of Absolute Values in Biochemical Fluorescence Spectroscopy. , 1972, Journal of research of the National Bureau of Standards. Section A, Physics and chemistry.