Electrodes for microfluidic devices produced by laser induced forward transfer

The laser induced forward transfer (LIFT) process was used to create conductive lines and pads for rapid prototyping and repairing microdevices. Single 0.1-10 μJ pulses from a 120 fs 800 nm titanium:sapphire laser were used to transfer films consisting of 40-80 nm thick gold to create the lines. Experiments were conducted in air ambient. The laser was focused using 4x and 10× microscope objectives and produced 5-20 μm diameter metal spots which were overlapped to produce conductive lines. Electrodes with widths between 10 and 50 μm have been produced and their resistances have been measured. The resistivities of these LIFT produced Au electrodes were found to be approximately (1-4) x 10 -6 fl m. It has also been shown that the conductivity of the lines can be further improved by electrical curing. The LIFT process was used to repair heaters for microfluidic applications and preliminarily create electrodes for control of electro-osmotic flow in microfluidic devices.