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Published September 8, 2009 | Erratum + Published
Journal Article Open

High-sensitivity microfluidic calorimeters for biological and chemical applications


High-sensitivity microfluidic calorimeters raise the prospect of achieving high-throughput biochemical measurements with minimal sample consumption. However, it has been challenging to realize microchip-based calorimeters possessing both high sensitivity and precise sample-manipulation capabilities. Here, we report chip-based microfluidic calorimeters capable of characterizing the heat of reaction of 3.5-nL samples with 4.2-nW resolution. Our approach, based on a combination of hard- and soft-polymer microfluidics, provides both exceptional thermal response and the physical strength necessary to construct high-sensitivity calorimeters that can be scaled to automated, highly multiplexed array architectures. Polydimethylsiloxane microfluidic valves and pumps are interfaced to parylene channels and reaction chambers to automate the injection of analyte at 1 nL and below. We attained excellent thermal resolution via on-chip vacuum encapsulation, which provides unprecedented thermal isolation of the minute microfluidic reaction chambers. We demonstrate performance of these calorimeters by resolving measurements of the heat of reaction of urea hydrolysis and the enthalpy of mixing of water with methanol. The device structure can be adapted easily to enable a wide variety of other standard calorimeter operations; one example, a flow calorimeter, is described.

Additional Information

© 2009 by the National Academy of Sciences. Edited by George M. Whitesides, Harvard University, Cambridge, MA, and approved July 22, 2009 (received for review February 9, 2009). Published online before print August 24, 2009, doi: 10.1073/pnas.0901447106 Author contributions: W.L., W.F., and M.L.R. designed research; W.L. performed research; B.W.A. contributed new reagents/analytic tools; W.L., W.F., B.W.A., and M.L.R. analyzed data; and W.L., W.F., B.W.A., and M.L.R. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission.


Correction for Lee et al., High-sensitivity microfluidic calorimeters for biological and chemical applications PNAS 2009 106 (42) 18040; published ahead of print September 30, 2009, doi:10.1073/pnas.0910433106

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Published - Lee2009p5909P_Natl_Acad_Sci_Usa.pdf

Erratum - 18040.4.full.pdf


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