Electrode compositions for laser patterned conductometric sensors

An electrode created with maskless metallization of Cu tracks ablated with laser direct structuring on a liquid crystal polymer can never achieve a quality comparable to sputtered layers on silicon, but has the advantage of being molded into complex 3D structures. As these electrodes on molded interconnected devices can function as conductometric sensors capable of detecting ion changes in a liquid it is of high interest to characterize a variety of metal systems in terms of electrode performance. The sensor models Cu|Ni-P|Pd|Au, Cu|Ni-P|Au, Cu|Pd|Au, Cu|Pd and Cu|Ag were tested for stability in an aqueous environment, and for sensitivity to detect a change in the conductance of a liquid environment. For both tests, the Cu|Pd|Au electrode had the most stable impedance and sensitivity, with the smallest variance (10 samples of each electrode composition pair tested). Inspection by Scanning Electron Microscope with Energy Dispersive X-ray spectroscopy explained this result.