Micro-assembled multi-chamber thermal cycler for low-cost reaction chip thermal multiplexing

Abstract

Abstract This paper presents a miniaturised multi-chamber thermal cycler capable of thermal multiplexing for high throughput polymerase chain reaction (PCR) of nucleic acids, using low-cost reaction chip. The thermal cycler has been fabricated in a micro-assembly manner using flip–chip bonding technique, which is batch manufacturable with good reproducibility. Silicon heating blocks in the multi-chamber array are mounted on a printed-circuit-board (PCB) substrate, with the later attached to a metal plate heat sink. Thermal cross-talk has been minimised by using thin and low thermal conductivity PCB. The preferred reaction chip containing multiple chambers is made of low-cost plastics, while other PCR compatible materials are also possible. The preliminary experiments show that with up to 20 μl sample in the thermally formed plastic chip, a full speed of 8 min for 30-cycle PCR is achievable. Thermal cross-talk of as less as 0.2% is obtained with the very thin PCB substrate (500 μm, FR4) and the plastic chip (100 μm PET), in a standard format of multi-chamber array. A temperature fluctuation of ±0.1 °C has been achieved during thermal multiplexing of up to 16 chambers, with each chamber consuming an average heating power of no more than 1.2 W. Finite element analysis (FEA) is conducted to optimise the thermal performance of the cycler. Experiments are in well agreements with the simulations.