A Low-Cost, Low-Power Consumption, Miniature Laser-Induced Fluorescence System for DNA Detection on a Microfluidic Device Sushil Shrinivasan, PhD a , Pamela M. Norris, PhD a , James P. Landers, PhD a,b , Jerome P. Ferrance, PhD a, * a Department of Chemistry, University of Virginia, McCormick Road, Charlottesville, VA 22904, USA b Department of Chemistry, University of Virginia Health Science Center, PO Box 400319, Chemistry 288A, Charlottesville, VA 22908, USA Analyte detection using laser-induced fluorescence (LIF) methods offers good sensitivity with low detection limits and, as the radiation from a laser source can be focused, provides for detection in very small volumes. This ability makes LIF detection a method of choice for detecting analytes on microfluidic devices, where the characteristic length scales are of the order of micrometers or smaller. Most often microchip LIF detection is applied for the detection of DNA. Because DNA is not naturally fluorescent, this requires mixing DNA with one of several, commercially available, interca- lating dyes to generate DNA–dye complexes that fluoresce when excited by light of the appropriate wavelength. The intensity of the fluorescent sig- nal is then directly proportional to the concentration of DNA. The power of this method is evidenced by the single-molecule detection of DNA on micro- fluidic devices as demonstrated by Haab and Mathies [1]. For these micro- chip LIF detection systems, a focused laser beam from an argon-ion laser is normally used for excitation, with a photomultiplier tube (PMT) for the col- lection of fluorescent signal [2,3]. Although there is no question that extremely sensitive LIF systems can be assembled for microchip-based analysis using powerful lasers and This article was originally published in JALA; August 2006. * Corresponding author. E-mail address: jpf3p@virginia.edu (J.P. Ferrance). 0272-2712/07/$ - see front matter Ó 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.cll.2006.12.010 labmed.theclinics.com Clin Lab Med 27 (2007) 173–181