Electrochemical-mechanical analysis of printed silver electrodes in a microfluidic device

Nanoparticulate printed silver is a core material to flexible, printed circuits. Some commercial silvers are of a sufficient purity that one may consider their use in electrochemical power sources and sensors. We establish an iterative rapid prototyping and measuring method, printing electrodes, annealing them under temperature conditions from 210 to 280°C, and cycling them in a microfluidic cell such that the electrolyte becomes the shearing medium. Electrode strength is quantified by the breakage due to generation of gas-phase oxygen at the electrode. This oxygen generation assisted breaking is found to be a function of the amount of oxygen generation only, independent of current density and electrolyte flow rate. Silver cured at 280°C for 60 min had highest strength and required an average of 241.8 mC/ mm² at electrode rupture; curing at 280°C for 20 min required only 203.8 mC/ mm² for failure. Silver strength is quantified as an oxidant storage medium in the forms Ag₂ O and AgO and as a printed reference electrode. Ag and AgO have higher shear strength compared to Ag₂ O. Thus, shear strength of silver oxide electrodes at potentials of 0.15-0.55 V against a printed silver reference depends on the oxidation state.