Abstract: The present invention provides microfluidic pScreen™ devices for quantifying the concentration of DNA fragments in a liquid sample by using magnetic-responsive silica micro-beads and nonmagnetic-responsive silica micro-beads. The devices of the present invention allow for rapid, simple and inexpensive quantification of DNA fragment concentration in a sample. The devices do not require complex instrumentation and can be performed in less than three minutes. Moreover, they are compatible with complex samples including, without limitation, unpurified PCR amplification products, and thus can be expected to seamlessly integrate into various common molecular biology techniques and workflows.