Fast Procedures for the Electrodeposition of Platinum Nanostructures on Miniaturized Electrodes for Improved Ion Sensing

Abstract

Nanostructured materials have attracted considerable interest over the last few decades to enhance sensing capabilities thanks to their unique properties and large surface area. In particular, noble metal nanostructures offer several advantages including high stability, non-toxicity and excellent electrochemical behaviour. However, in recent years the great expansion of point-of-care (POC) and wearable systems and the attempt to perform measurements in tiny spaces have also risen the need of increasing sensors miniaturization. Fast constant potential electrodeposition techniques have been proven to be an efficient way to obtain conformal platinum and gold nanostructured layers on macro-electrodes. However, this technique is not effective on micro-electrodes. In this paper, we investigate an alternative one-step deposition technique of platinum nanoflowers on micro-electrodes by linear sweep voltammetry (LSV). The effective deposition of platinum nanoflowers with similar properties to the ones deposited on macro-electrodes is confirmed by morphological analysis and by the similar roughness factor (~200) and capacitance (~18 μ F/mm 2 ). The electrochemical behaviour of the nanostructured layer is then tested in an solid-contact (SC) L i + -selective micro-electrode and compared to the case of macro-electrodes. The sensor offers Nernstian calibration with same response time (~15 s) and a one-order of magnitude smaller limit of detection (LOD) ( 2.6 × 10 − 6 ) with respect to the macro-ion-selective sensors (ISE). Finally, sensor reversibility and stability in both wet and dry conditions is proven.

A Wearable Electrochemical Sensing System for Non-Invasive Monitoring of Lithium Drug in Bipolar Disorder

“…A one-step potentiostatic electrodeposition process was used for Platinum nanostructuration. The roughness factor was calculated as the ratio between the electrochemical active area (obtained from the area of the Platinum oxide reduction peak in CV in sulphuric acid as described in [28], [29]) and the geometrical area of the electrodes. The similar value (∼200) with respect to the one on rigid substrate proves the efficiency of the nanoflowers deposition on our flexible microfabricated electrochemical platform.…”

An Evolving Insight into the Progress of Material Design for Membrane‐Based Electrochemical Lithium Ion Detection

“…where CP° is the neutral conducting polymer, CP + is the oxidized conducting polymer, A − is the anion (e.g., the lipophilic ionic site in the ion selective membrane or the doping ion in conducting polymers) and Li + is the lithium ion. [6,25,87] The ion-to-electron transduction process for solid-contact functional materials with a large contact area is based on double-layer capacitance that forms at solid-contact and ionselective membrane interface. As shown in Figure 8c, charge carriers are asymmetrically distributed on both sides of the solid-contact and ion-selective membrane interface.…”

“…[83,93] The redox capacitance of conducting polymers depended on their inherent ionic and electronic conductivity properties, which can be adjusted by doping. [6,25,87] In addition to the unique properties of conducting polymers, these materials have some limitations, such as light or pH sensitivity, unwanted electrochemical side reactions with redox interferences, dissolved oxygen and CO 2 and also salt residues from the polymerization process that increase the probability of formation of a water layer. [94] Various strategies have been proposed to overcome these limitations and improve the performance of conducting polymers as a solid contact.…”

“…ciii) SEM images of platinum nanostructures deposited by linear sweep voltammetry with the applied voltage between 0 and −0.8 V. Reproduced under the terms of the CC-BY 4.0 license. [87] Copyright 2019, The Authors, published by MDPI.…”

Amperometric Sensing of Carbon Monoxide: Improved Sensitivity and Selectivity via Nanostructure-Controlled Electrodeposition of Gold

“…The synthesis of metallic nanostructures has been studied by many researchers because these materials are applicable to various fields such as sensors [13,14], electrocatalysis [15], heterogeneous catalysis [16], and fuel cells [17]. The surface properties of these nanostructures can be changed with the variation of the types/compositions of metals, dimensions, and shapes [18,19].…”