Infrared Temperature Control System for a Completely Noncontact Polymerase Chain Reaction in Microfluidic Chips

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• 作者：Michael G. Roper ; Christopher J. Easley ; Lindsay A. Legendre ; Joseph A. C. Humphrey ; and ; James P. Landers
• 刊名：Analytical Chemistry
• 出版年：2007
• 出版时间：February 15, 2007
• 年：2007
• 卷：79
• 期：4
• 页码：1294 - 1300
• 全文大小：287K
• 年卷期：v.79,no.4(February 15, 2007)
• ISSN：1520-6882

文摘

A completely noncontact temperature system is describedfor amplification of DNA via the polymerase chain reaction(PCR) in glass microfluidic chips. An infrared (IR)-sensitive pyrometer was calibrated against a thermocoupleinserted into a 550-nL PCR chamber and used to monitorthe temperature of the glass surface above the PCRchamber during heating and cooling induced by a tungsten lamp and convective air source, respectively. A timelag of less than 1 s was observed between maximumheating rates of the solution and surface, indicating thatthermal equilibrium was attained rapidly. Moreover, thetime lag was corroborated using a one-dimensional heat-transfer model, which provided insight into the characteristics of the device and environment that caused thetime lag. This knowledge will, in turn, allow for futuretailoring of the devices to specific applications. To alleviatethe need for calibrating the pyrometer with a thermocouple, the on-chip calibration of pyrometer was accomplished by sensing the boiling of two solutions, waterand an azeotrope, and comparing the pyrometer outputvoltage against the known boiling points of these solutions.The "boiling point calibration" was successful as indicatedby the subsequent chip-based IR-PCR amplification of a211-bp fragment of the B. anthracis genome in achamber reduced beyond the dimensions of a thermocouple. To improve the heating rates, a parabolic goldmirror was positioned above the microfluidic chip, whichexpedited PCR amplification to 18.8 min for a 30-cycle,three-temperature protocol.