A Solid‐State Reference Electrode Based on a Self‐Referencing Pulstrode

Abstract

The design of solid-state reference electrodes without liquid junction is of great importance to allow for miniature and costeffective electrochemical sensors in environmental and biomedical applications. To address this, we propose here a pulse control protocol using an Ag/AgI element as reliable solid-state reference electrode. It involves the local release of iodide by a cathodic current that is immediately followed by an electromotive force (EMF) measurement that serves as the reference potential. The recapture of iodide ions is achieved by potentiostatic control. This results in intermittent potential values that are reproducible to less than one millivolt (SD = 0.27 mV, n = 50). The ionic strength is shown to influence the activity coefficient of released iodide in accordance with the Debye-Hückel equation, resulting in a predictable change of the potential reading. The principle is applied to potentiometric potassium detection with a valinomycin-based ion-selective electrode (ISE), demonstrating a completely solid-state sensor configuration. The resulting calibration curves compare quantitatively to a commercial liquid junction-based reference electrode, even in spiked artificial sweat samples. This approach offers a promising strategy to the design of all-solid-state electrochemical sensing probes.

Solid-Contact Ion-Selective Electrodes: Response Mechanisms, Transducer Materials and Wearable Sensors

“…Currently, polymer-based [92][93][94], ionic liquid-junction [95][96][97], and lipophilic salts modified-polymer [98,99] are the main solid-state REs. Recently, a solid-state RE of Ag/AgI based on a self-referencing pulstrode offers a new strategy [100]. 3The leaking of ISM components is another issue that should be emphasized.…”

Potentiometric Sensing

“…Bakker’s group proposed a novel concept of a solid-state reference electrode using a Ag/AgI element . The concept is based on the local release of iodide by a cathodic current that is immediately followed by an electromotive force measurement that serves as the reference potential (see Figure ).…”

“…Working principle of a pulsed self-referencing Ag/AgI electrode . The protocol includes four steps: (1) recording of the initial open-circuit potential; (2) local release of iodide ions by applying a cathodic current pulse; (3) recording the EMF at the open circuit (at the point indicated as the red circle); (4) recapture of the released iodide ions by applying a constant potential pulse based on the initial OCP value.…”

“…Bakker's group proposed a novel concept of a solid-state reference electrode using a Ag/AgI element. 9 The concept is based on the local release of iodide by a cathodic current that is immediately followed by an electromotive force measurement that serves as the reference potential (see Figure 1). The subsequent recapture of iodide ions is achieved by potentiostatic control, chosen similar to the open circuit potential before the iodide release pulse.…”

An Integrated Multi‐Function Heterogeneous Biochemical Circuit for High‐Resolution Electrochemistry‐Based Genetic Analysis

“…Thewhole genetic circuit is operated under as imple Boolean logic design principle.T o evaluate the applicability of the integrated multi-function circuit, we implemented this molecular network abstraction into ab ioanalytical system operating on an electrochemical interface,w hich serves as as imple and cost-effective transduction system, capable of rapidly curating molecular information and transducing into data. [3] Bioanalytical strategies have been extensively developed toward better sensitivity,s implicity and selectivity, [4] while valid strategies can be further integrated into aportable,costeffective,r apid transduction platform for an ideal point-ofcare system. So far, ah igh-resolution molecular analytical strategy,capable of differentiating infinitesimal concentration variation, which is essential to understand the critical threshold limit of biomolecules,has not been realized with asimple biosensing system.…”