Total integrated slidable and valveless solid phase extraction-polymerase chain reaction-capillary electrophoresis microdevice for mini Y chromosome short tandem repeat genotyping

Abstract

A fully integrated slidable and valveless microsystem, which performs solid phase DNA extraction (SPE), micro-polymerase chain reaction (mu PCR) and micro-capillary electrophoresis (mu CE) coupled with a portable genetic analyser, has been developed for forensic genotyping. The use of a slidable chip, in which a 1 mu L-volume of the PCR chamber was patterned at the center, does not necessitate any microvalves and tubing systems for fluidic control. The functional micro-units of SPE, mu PCR, and mu CE were fabricated on a single glass wafer by conventional photolithography, and the integrated microdevice consists of three layers: from top to bottom, a slidable chip, a channel wafer in which a SPE chamber, a mixing microchannel, and a CE microchannel were fabricated, and a Ti/Pt resistance temperature detector (RTD) wafer. The channel glass wafer and the RID glass wafer were thermally bonded, and the slidable chip was placed on the designated functional unit. The entire process from the DNA extraction using whole human blood sample to identification of target Y chromosomal short tandem repeat (STR) loci was serially carried out with simply sliding the slidable chamber from one to another functional unit. Monoplex and multiplex detection of amelogenin and mini Y STR loci were successfully analysed on the integrated slidable SPE-mu PCR-mu CE microdevice by using 1 mu L whole human blood within 60 min. The proposed advanced genetic analysis microsystem is capable of point-of-care DNA testing with sample-in answer-out capability, more importantly, without use of complicated microvalves and microtubing systems for liquid transfer.