Non-invasive temperature analysis of micro polymerase chain reaction chip by using liquid crystals and a micro-Raman spectroscopy

Abstract

Liquid crystal (LC) thermometry and micro-Raman spectroscopy system were introduced for non-invasive temperature analysis of micro polymerase chain reaction (PCR) chip. The silicon-based micro PCR chip was fabricated by microelectromechanical system (MEMS) technology, and it consisted of a microchannel and a platinum thin film heater and sensor. The temperature of the chip was controlled by in situ temperature control system with the nonlinear feedback proportional-integral control scheme. As the results of the LC thermometry, the average microchannel temperature near annealing temperature (55 oC) was similar to the set temperature measured by the Pt film heater and it was lowered by nearly 1 oC than the control temperature near extension temperature (72 oC). The temperature deviation measured by the LC thermometry were less than 1.5 oC ± 0.5 oC and 3 oC ± 0.3 oC at the annealing and the extension temperature, respectively. The temperature deviation measured by the Raman thermometry varied from -1.0 oC to +0.1 oC at the annealing temperature.