Flexible Disk Ultramicroelectrode for High-Resolution and Substrate-Tolerable Scanning Electrochemical Microscopy...

Area of Science:

• Electrochemistry
• Materials Science
• Nanotechnology

Background:

• Fabricating flexible ultramicroelectrodes (UMEs) is crucial for sensitive electrochemical analysis.
• Traditional UMEs often suffer from tip crash and sample damage.
• Developing adaptable and robust UME probes remains a key challenge.

Purpose of the Study:

• To develop a simple, universal, and efficient strategy for fabricating flexible platinum (Pt) disk ultramicroelectrodes (UMEs).
• To enable adjustable probe characteristics (RG ratio, tip length, stiffness) for diverse experimental needs.
• To create reusable UME probes with enhanced durability and minimal sample interaction.

Main Methods:

• Utilized a pulled borosilicate glass micropipette as a mold for shaping flexible epoxy resin tips.
• Optimized fabrication parameters including resin/hardener ratio and HF etching conditions for desired flexibility and deformation resistance.
• Characterized probe geometry, electrochemical properties, and sheath integrity using optical microscopy, cyclic voltammetry, and SECM approach curves.

Main Results:

• Successfully fabricated flexible 25 μm Pt disk UMEs with adjustable RG ratio (<3), tip length, and stiffness.
• Demonstrated efficient probe preparation (≥10 probes within 10 h) and renewable electroactive areas via blade cutting.
• Confirmed excellent electrochemical performance and structural integrity of the flexible probes after fabrication and cutting.

Conclusions:

• The developed method provides a highly efficient and versatile approach for creating flexible Pt disk UMEs.
• These flexible probes offer superior performance in various scanning modes (contact and contactless) with minimal risk of tip crash or sample damage.
• The probes are compatible with diverse sample topographies, including 3D structures, stiff, and soft materials, overcoming limitations of traditional UMEs.