Enhancement of thermal uniformity for a microthermal cycler and its application for polymerase chain reaction

Thermal uniformity is essentially important for micro reactors which require precise control of critical reaction temperatures. Accordingly, we report a new approach to increase the temperature uniformity inside a microthermal. cycler, especially for polymerase chain reaction (PCR). It enhances the thermal uniformity in the reaction region of a PCR chip by using new array-type microheaters with active compensation (AC) units. With this approach, the edges of the microthermal cyclers which commonly have significant temperature gradients can be compensated. Significantly, the array-type microheaters provide higher uniformity than conventional block-type microheaters. Besides, experimental data from infrared (IR) images show that the percentages of the uniformity area with a thermal variation of less than 1 degrees C are 63.6%, 96.6% and 79.6% for three PCR operating temperatures (94, 57 and 72 degrees C, respectively) for the new microheaters. These values are significantly better than the conventional block-type microheaters. Finally, the performance of this proposed microthermal cycler is successfully demonstrated by amplifying a detection gene associated with Streptococcus Pneumoniae (S. Pneumoniae). The PCR efficiency of the new microthermal cycler is statistically higher than the block-type microheaters. Therefore, the proposed microthermal cycler is suitable for DNA amplification which requires a high temperature uniformity and is crucial for micro reactors with critical thermal constraints. (c) 2007 Elsevier B.V. All rights reserved.