Temperature measurement in microfluidic systems using a temperature-dependent fluorescent dye

A technique is described for the measurement of fluid temperatures in micro fluidic systems based on temperature-dependent fluorescence. The technique is easy to implement with a standard fluorescence microscope and CCD camera . In addition, the method can be used to measure fluid temperatures with mi crometer spatial resolution and millisecond time resolution. The efficacy o f the method is demonstrated by measuring temperature distributions resulti ng from Joule heating in a variety of microfluidic circuits that are electr okinetically pumped. With the equipment used for these measurements, fluid temperatures ranging from room temperature to 90 degreesC were measured wit h a precision ranging from 0.03 to 3.5 degreesC-dependent on the amount of signal averaging done. The spatial and temporal resolutions achieved were 1 mum and 33 ms, respectively.