Transient liquid crystal thermometry of microfabricated PCR vessel arrays

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