Free flow isotachophoresis in an injection moulded miniaturised separation chamber with integrated electrodes

An injection moulded free flow isotachophoresis (FFITP) microdevice with integrated carbon fibre loaded electrodes with a separation chamber of 36.4 mm wide, 28.7 mm long and 100 μm deep is presented. The microdevice was completely fabricated by injection moulding in carbon fibre loaded polystyrene for the electrodes and crystal polystyrene for the remainder of the chip and was bonded together using ultrasonic welding. Two injection moulded electrode designs were compared, one with the electrode surface level with the separation chamber and one with a recessed electrode. Separations of two anionic dyes, 0.2 mM each of amaranth and acid green and separations of 0.2 mM each of amaranth, bromophenol blue and glutamate were performed on the microdevice. Flow rates of 1.25 ml min−1 for the leading and terminating electrolytes were used and a flow rate of 0.63 ml min−1 for the sample. Electric fields of up to 370 V cm−1 were applied across the separation chamber. Joule heating was not found to be significant although out-gassing was observed at drive currents greater than 3 mA.