Influence of the Printing Pastes’ Rheology on Screen-Printed Electrochemical Sensors’ Performance ^†

This study concerns printed, disposable voltammetric electrodes for bioanalytical applications. Sensing electrodes’ electrochemically active surface area was found to relate to the screen-printing pastes’ rheology and manufacturing parameters. The sensors’ response was examined for constant carbon content in the electrode material and varying additions of surfactants and solvents, as well as the forces affecting the printing process. The printing pastes employed graphene nanoplatelets with the addition of carbon black as the functional phase and various polymers (PMMA, TPU, and others) as the composite matrix. Technological parameters examined included: the pressure and movement rate during the printing cycle, screen mesh density, curing, and ozonizing time. The rheological properties determined for each paste were: static viscosity, zero viscosity, and yield stress. To estimate active surface area values, sensors were immersed in redox couple solution and employed for CV measurements at varying scan rates. Finally, the active surface area was calculated according to the transformed Randles–Sevcik equation. The results were compared to electron transfer resistance and surface roughness. Correlation analysis was performed for the above parameters. The obtained statistical relationships will allow fine-tuning of the printed sensors’ performance as well as the faster development of new applications of this technology in analytical devices.