Optothermal sample preconcentration and manipulation with temperature gradient focusing
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In this article, we present an optothermal analyte preconcentration method based on temperature gradient focusing. This approach offers a flexible, noninvasive technique for focusing and transporting charged analytes in microfluidics using light energy. The method uses the optical field control provided by a digital projector as established for particle manipulation, to achieve analogous functionality for molecular analytes for the first time. The optothermal heating system is characterized and the ability to control of the heated zone location, size, and power is demonstrated. The method is applied to concentrate a sample model analyte, along a microcapillary, resulting in almost 500-fold local concentration increase in 15 min. Optically controlled upstream and downstream transport of a focused analyte band is demonstrated with a heater velocity of ∼170 μm/min.
KeywordsOptothermal Temperature gradient focusing Preconcentration Analyte manipulation Microfluidics
The authors thank the financial support of the Natural Sciences and Engineering Research Council of Canada NSERC through discovery grants to MB and DS, BC Innovation Council (BCIC) through research scholarship to MA, and the Canada Research Chair Program.
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