An inverse-designed electrochemical platform for analytical applications

Screen-printed electrodes are the most recent generation of low-cost, mass-produced, sensitive and portable devices for the measurement of analytes of interest. The responses of these platforms, in terms of current intensity and reproducibility, are strongly influenced by factors such as printing procedures, type of ink, substrates, etc. In this paper, an improved inverse-designed screen-printed electrode (IDSPE) is proposed. The electrochemical performance is compared with that obtained using classical screen printed electrodes (SEPs), showing enhanced sensitivity and signal-to-noise ratio (background current minimization 32 ± 3 nA and 0.64 ± 0.01 nA, for SPE and IDSPE, respectively). A full comparison between inverse and classical screen-printed electrodes is carried out using various electroactive species (potassium ferricyanide, ascorbic acid, hexaammineruthenium(III) chloride and NADH) and two different electrochemical techniques (cyclic and square-wave voltammetry). In tests conducted with potassium ferricyanide the sensitivity of the IDSPE shows a nearly four-fold improvement, and a limit of detection three times better than the values obtained employing the classical SPE. The reproducibility (RSD%) in tests conducted with ascorbic acid is 6% and 12% for IDSPE and SPE, respectively. Moreover, surface modification of both screen-printed electrodes (SPE and IDSPE) with biochar obtained from recycled brewers waste (Bio-SPEs and Bio-IDSPEs), further improves their electrochemical performance, in terms, for example, of the heterogeneous electron transfer constant (0.0024 and 0.0018 for Bio-SPE and Bio-IDSPE, respectively).