We have demonstrated the ability to perform real-time homogeneous, sequence specific detection of PCR products in silicon microstructures. Optimal design/ processing result in equivalent performance (yield and specificity) for high surface-to-volume silicon structures as compared to larger volume reactions in polypropylene tubes. Amplifications in volumes as small as 0.5 microl and thermal cycling times reduced as much as 5-fold from that of conventional systems have been demonstrated for the microstructures.

Abstract-Polymerase chain reaction (PCR) using micromachined structures promises improved temperature uniformity and cycling time together with decreased reagent and sample volumes. Thermal design of these structures will benefit from measurements of the temperature distribution in the reacting liquid. We report measurements of temperature uniformity and time constant in a microfabricated 18-vessel array using encapsulated liquid crystals suspended in the liquid. Separate sets of crystals are used to image temporal and spatial temperature variations near the processing thresholds of 55 C and 95 C with a resolution of 0.1 C. While the thermometry technique developed here is particularly useful for characterizing microfabricated PCR systems, it can also aid with the thermal design of a broad variety of microfluidic devices. [330]

are concordant with traditional methods, with 88% first pass success rates for both the CODIS and PowerPlex 16 loci. Average peak height ratios were 0.89 for buccal swabs. The system produces full profiles from swabs with at least 176 ng of saliva DNA. Rapid DNA identification systems will significantly enhance capabilities for forensic labs, intelligence, defense, law enforcement, refugee and immigration applications, and kinship analysis.

Simultaneous measurements of absorption and fluorescence in a pulsed planar supersonic jet are used to determine fluorescence quantum yields of nine single vibronic levels (SVL’s) in the S2 electronic manifold of azulene. The quantum yield at the spectroscopic origin is 0.042±0.004, somewhat larger than that obtained in earlier room-temperature measurements in solution. Most SVL’s have quantum yields within experimental error of this value, except for two SVL’s characterized by large-amplitude motion at carbons 1 and 3, whose quantum yields are about 0.06. Our quantum yield data are combined with recent lifetime measurements by other workers to obtain fluorescence and internal conversion decay rates for each SVL. The radiative rates vary by a factor of 2, as expected for the S2↔S0 transition, whose absorption strength is strongly enhanced by vibronic coupling between S2 and S4. The internal conversion rates increase with excess vibrational energy in a way that parallels the extent of intramolecular vibrational redistribution (IVR), as determined by other workers using SVL emission and time-and-energy-resolved emission. Thus, the internal conversion rates in this electronic state appear to exhibit behavior typical of large aromatic molecules.

Most microfluidic systems rely on one of two manners of fluid transport: pressure-driven or electrokinetically-driven flow. This investigation focuses on describing these flows in microfabricated channels and small diameter capillary tubes. Flow characterization is accomplished by interrogation of micron-scale fluid regions through a powerful, non-intrusive flow imaging technique. Interesting phenomena have been observed from these detailed examinations. Our results are presented in conjunction with an evaluation of mechanisms that potentially explain observed deviations from the Helmholtz-Smoluchowski equation. In particular, we show that observed perturbations of electrokinetic flow in open capillaries might be caused by induced pressure gradients. We also show how these induced pressure gradients may globally perturb the flow in an electrokinetically-driven microfluidic system.