Electrochemical Improvements Can Be Realized via Shortening the Length of Screen-Printed Electrochemical Platforms

Abstract

Screen-printed electrodes (SPEs) are ubiquitous within the field of electrochemistry and are commonplace within the arsenal of electrochemists. Their popularity stems from their reproducibility, versatility, and extremely lowcost production, allowing their utilization as single-shot electrodes and thus removing the need for tedious electrode pretreatments. Many SPE studies have explored changing the working electrode composition and/or size to benefit the researcher's specific applications. In this paper, we explore a critical parameter of SPEs that is often overlooked; namely, we explore changing the length of the SPE connections. We provide evidence of resistance changes through altering the connection length to the working electrode through theoretical calculations, multimeter measurements, and electrochemical impedance spectroscopy (EIS). We demonstrate that changing the physical length of SPE connections gives rise to more accurate heterogeneous electrode kinetics, which cannot be overcome simply through IR compensation. Significant improvements are observed when utilized as the basis of electrochemical sensing platforms for sodium nitrite, β-nicotinamide adenine dinucleotide (NADH), and lead (II). This work has a significant impact upon the field of SPEs and highlights the need for researchers to characterize and define their specific electrode performance. Without such fundamental characterization as the length and resistance of the SPE used, direct comparisons between two different systems for similar applications are obsolete. We therefore suggest that, when using SPEs in the future, experimentalists report the length of the working electrode connection alongside the measured resistance (multimeter or EIS) to facilitate this standardization across the field.

The effect of water ingress on additively manufactured electrodes

“…Previous literature using screen-printed electrodes highlighted how increasing electrode resistance causes a decrease in k 0 obs. due to Ohmic drop, 26 but the opposite trend was seen here, with, for example, the NA-I samples showing increased k 0 obs. compared to the NA-NI samples despite also displaying a large increase in resistance.…”

“…Indeed, the role of circuit resistance with regards to electrochemical measurements is well known as Ohmic drop, but is typically compensated for so as to become negligible. 26 Nonetheless, the suggestion that changing Ohmic drop causes the change in current flow seen upon water ingress is supported by the fact that the average ratio of the current measured at a potential of À249 mV for NA-NI/NA-I samples at 50 mV s À1 was found to be 1.5 AE 0.2, the uncertainty of which overlaps with the ratio of average resistances NA-I/NA-NI, 1.8 AE 0.2 (Mean AE S.D.). This proportionality is consistent with Ohm's law: for identical circuits at a constant potential, multiplying resistance by a factor of approximately 1.8 should cause a current decrease of approximately 1/1.8, as described above.…”

Molecularly Imprinted Polymer Nanoparticles Enable Rapid, Reliable, and Robust Point-of-Care Thermal Detection of SARS-CoV-2

“…The graphite SPEs (3.1 mm in diameter) were produced by screen-printing a graphite ink formulation (Gwent Electronic Materials Ltd., Monmouthshire, UK) onto a standard polyester substrate. 56 This was followed by curing at 60 °C for 30 min with a dielectric material (Gwent Electronic Materials Ltd.), which was used to define the rectangular shape of the SPE for easy handling. 57 The experimental protocol for the electrografting procedure ( Figure 1 d) is comprehensively outlined in our previous work.…”

An alternative ready-to-use electrochemical immunosensor for point-of-care COVID-19 diagnosis using graphene screen-printed electrodes coupled with a 3D-printed portable potentiostat

“…Carbon paste was uniformly mixed with 5 wt% graphene nanoplatelets by ball milling at 1000 rpm for 1 h and then screen-printed onto a PET substrate as graphene screen-printed electrodes (GSPEs) comprising a working electrode (WE) and a counter electrode (CE). The WE was designed to have high active electrode area of 12.57 mm 2 and short electrode length of 25 mm in order to minimize the electrode resistance [ 27 , 28 ]. Next, silver/silver chloride paste was screen printed to form a references electrode (RE) and insulating paste was screen-deposited over parts of electrodes to define active electrode area.…”