Focusing analytes from 10 μL into 500 pL: On-chip processing of large volumes using isotachophoresis

Abstract

Significant limitation of many microfluidics-based diagnostics assays is their inability to process sufficiently large sample volumes. This is particularly important for cases where the biological target exists at such low concentrations that its presence in the microchannel becomes probabilistic. We present a novel microfluidic chip capable of focusing a target analyte from sample volumes on the order of 10 μL into 500 pL volumes using isotachophoresis (ITP). We demonstrate the potential of this approach for highly sensitive detection of both biomolecular targets (DNA, down to 100 fM) and of discrete targets (whole bacteria, down to 1000 cfu/mL).