Development of a conductivity-based photothermal absorbance detection microchip using polyelectrolytic gel electrodes
Honggu Chun1, Patty J Dennis2, Erin R Ferguson Welch2
1Department of Chemistry, University of North Carolina at Chapel Hill, Chapman Hall, CB#3216, Chapel Hill, NC 27599, United States; Department of Biomedical Engineering, Korea University, Hana Science Hall 466, Seoul, 02841, Republic of Korea.
Abstract:
The development and application of polyelectrolytic gel electrodes (PGEs) for a microfluidic photothermal absorbance detection system is described. The PGEs are used to measure changes in conductivity based on heat generation by analytes absorbing light and changing the solution viscosity. The PGEs are suitable for direct contact conductivity measurements since they do not degrade with exposure to high electric fields. Both a 2-electrode system with DC voltages and a 3-electrode system with AC voltages were investigated. Experimental factors including excitation voltage, excitation frequency, laser modulation frequency, laser power, and path length were tested. The limits of detection for the 3-electrode and 2-electrode systems are 500nM and 0.55nM for DABSYL-tagged glucosamine, respectively. In addition, an electrokinetic separation of a potassium, DABSYL-tagged glucosamine, Rhodamine 6G, and Rhodamine B mixture was demonstrated.
