Micro total analysis systems for chemical and biological analysis have attracted much attention.However,microchips for sample preparation and especially DNA purification are still underdeveloped.This work describes a solid phase extraction chip for purifying DNA from biological samples based on the adsorption of DNA on bare silica beads prepacked in a microchannel.The chip was fabricated with poly-dimethylsiloxane.The silica beads were packed in the channel on the chip with a tapered microchannel to form the packed bed.Fluorescence detection was used to evaluate the DNA adsorbing efficiency of the solid phase.The polymerase chain reaction was used to evaluate the quality of the purified DNA for further use.The extraction efficiency for the DNA extraction chip is approximately 50% with a 150-nL extraction volume.Successful amplification of DNA extracted from human whole blood indicates that this method is compatible with the polymerase chain reaction.