Flexible disk ultramicroelectrode: Facile preparation and high-resolution scanning electrochemical microscopy imaging

Background: Scanning electrochemical microscopy (SECM) is a kind of scanning probe technology that enables the obtainment of surface morphology and electrochemical information by recording changes in Faraday current triggered by the movement of probe.

Results: In this work, flexible disk ultramicroelectrode (UME) with highly repeatable geometry are fabricated through a simple and universal strategy that involves vacuum pulling the glass capillaries inserted with platinum wire (gold wire, carbon fiber, etc.), followed by a rapidly heated sealing and polishing process. Based on the optical and electrochemical characterization, the as-prepared UMEs possess favorable geometric shape with a small RG value from 1.7 to 2. Consequently, when applied as probe components for SECM imaging on interdigital electrodes, it can achieve excellent spatial resolution and high sensitivity at short working distances. Moreover, due to the outstanding flexibility, the as-prepared UMEs can be minimally damaged arising from tip-sample collision and produce invisible trace on apple peel after the contact scanning, which is far superior to the traditional UME and suggests the application potential in bio-related fields.

Significance: Our work will inspire the application of flexible UMEs as probe components in SECM, and consequently promote the widespread use of SECM with reduced collision threshold and low operational difficulty.