Exploring interdigitated electrode arrays screen-printed on paper substrates for steady-state electrochemical measurements

This research explores using interdigitated electrode arrays (IDE) screen-printed on paper substrate for electrochemical measurements in steady state. Because the steady state is strongly related to IDE dimensions, the accuracy and fabrication reproducibility were assessed for 120- and 200-mesh stencils. Simulations were used to predict the limiting current and time response and as a benchmark for comparison with the experimental results. For accurate comparison, evaporation was prevented using a homemade humidity box, which enabled measurements for periods as long as 30 min. Although cyclic voltammetry measurements in steady state were possible, this required  15 min per cycle when using the smallest electrodes (band width of 0.205 mm). Chronoamperometric measurements reaching steady state were also possible, requiring  5 min for the largest electrodes (band width of 0.376 mm). Regarding the measurement reproducibility, the relative standard deviations (RSD) of current and response time were  12% and  26%, respectively. We attribute this to the fabrication reproducibility (8% RSD). Experimental currents were  30% to  34% of their simulated counterparts. Conversely, the simulated response times were  30% to  50% of their experimental counterparts. We ascribe these discrepancies to the porosity of wet paper (Whatman 2 CHR), estimated to be  31%.