Capillary Tube Resistive Thermal Cycling

Neal A. Friedman, Deirdre R. Meldrum

Research output: Contribution to journalArticlepeer-review

52 Scopus citations


A system that performs rapid thermal cycling of microliter and smaller liquid volumes inside glass capillary tubes that have an optically transparent thin film of indium-tin oxide (ITO) covering the exterior is described. The ITO film acts as both a heater and a temperature sensor, while cooling is accelerated with forced air. Unlike existing batch-mode thermal cycling systems, this system allows control over each sample's temperature profile. Temperature transition rates of 44 degrees Celsius per second during heating and 15 degrees Celsius per second during cooling have been achieved, allowing successful polymerase chain reaction (PCR) experiments to be performed in 20 min. Capillary external temperature can be regulated typically to within ±0.25 degrees Celsius, and peak temperatures more than 800 degrees Celsius have been demonstrated. Capillary internal (sample) temperatures at present are controllable typically to within 2 degrees Celsius. The resistive film can be used as a temperature sensor, and the optical transparency of the thin-film coating could permit fluorescent monitoring of the sample during thermal cycling, making this method well suited for real-time quantitative PCRs.

Original languageEnglish (US)
Pages (from-to)2997-3002
Number of pages6
JournalAnalytical Chemistry
Issue number14
StatePublished - Jul 15 1998
Externally publishedYes

ASJC Scopus subject areas

  • Analytical Chemistry


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