A Low-Cost, Low-Power, Consumption Miniature Laser-Induced Fluorescence System for DNA Detection on a Microfluidic Device

Abstract

With a focus on low-cost and low-power consumption, a miniature laser-induced fluorescence (LIF) detection system was assembled using a 635 nm red diode laser as the excitation source and a photodiode element coupled with an operational amplifier for signal collection. The primary elements of the miniature system, namely the laser and the detection system, cost a combined $70 and required only 270 mW of power for operation. When compared to conventional systems assembled using an argon-ion laser source and a photomultiplier tube, this represents a 98% decrease in the cost, and greater than 5000-fold decrease in power consumption. Limits of detection (LOD) and quantitation (LOQ) of the miniature system, evaluated on a microfluidic device for Nile Blue dye diluted in ethanol, were approximately 15 and 40 nM, respectively. Detection of λ-phage DNA on a microfluidic device using the miniature system was performed after mixing with an intercalating dye, TO-PRO 3. The LOD and LOQ of λ-phage DNA after TO-PRO 3 intercalation were approximately 1 and 4 ng/μL, respectively. Quantitation of DNA on microdevices using the miniature LIF detection system was also performed with an error of less than 15%. This detection system is a step in the direction of commercializing microfluidic instrumentation by reducing the cost and power required for operation. (JALA 2006;11:254–9)