Digital polymerase chain reaction（ d PCR） is a powerful method for the absolute quantification of nucleic acids. However

the available d PCR platforms require either expensive instruments or complicated operation

which limit their extensive applications. A simple

inexpensive and reliable d PCR microfluidic chip is designed and fabricated

using the gas expansion molding technique which is assisted by a silicon wafer mold containing arrays of deep etched pits. The novel spherical cavity can provide a stable accommodation for partitioned droplets

ensuring a reliable and robust discretization of samples. Furthermore

a degas-driven flow is used for selfpriming and self-partition of samples

which significantly simplified the chip operation. Feasibility of the d PCR chip is demonstrated by accurately detecting EGFR exon 19.