Miniaturized system for isotachophoresis assays

We present an inexpensive hand-held device (240 g) that implements microchip isotachophoresis (ITP) with laser induced fluorescence (LIF) detection. This self-contained instrument integrates the functionality required for high voltage generation onto a microelectronic chip, includes LIF detection and is powered by a universal serial bus (USB) link connected to a laptop computer. Using this device we demonstrate focusing and detection of a fluorescent species with a limit of detection of 100 pM. We show that the response of the detector is linear with the initial analyte concentration, making this device suitable for quantitative analysis. We also demonstrate the use of our simulation tools for design and prediction of ITP assays, and validate these results with a demonstration of multiplexed indirect detection of (unlabeled) analytes performed using the device. We find good agreement between simulations and experimental results. Using a label-free isotachaphoresis assay implemented in the hand-held device we detect two explosives and an endocrine disruptor spiked in river water, with no prior sample processing.