Temperature measurement in microfluidic devices. (News Briefs).

NIST scientists have developed a new method for measuring the temperature in microfluidic devices. Microfluidic, or so-called "lab-on-a-chip," devices are miniaturized chemical and biochemical analysis systems that may one day replace conventional bench top instruments. The ability to measure and control fluid temperatures within lab-on-a-chip devices can be very important for efficient electrophoretic separations and for enzyme-activated reactions. In spite of its importance, only a few techniques have been reported for the measurement of fluid temperatures in these hair-thin fluid channels. The drawbacks to these techniques are that they are difficult to implement (involving either NMR or Raman spectroscopy) and are limited in resolution, so that rapid spatial and temporal variations of temperature cannot be measured. The new temperature measurement technique developed at NIST is simple to implement, requiring only standard video and fluorescence microscopy equipment, and can be used for temperature measure ments with simultaneous micrometer spatial resolution and millisecond time resolution. The measurement technique is based on the temperature dependence of the fluorescence intensity of a dilute fluorophore added to the fluid, and thereby takes advantage of the inherently high signal-to-noise ratio of fluorescence-based measurements. A description of the technique was recently published in the journal Analytical Chemistry.

CONTACT: David Ross, [phone]; [e-mail] or Laurie Locascio, [phone]; [e-mail].