Bridge SECM and SECCM with a Coaxial Microelectrode@Micropipette Probe.

Area of Science:

• Electrochemistry
• Materials Science
• Analytical Chemistry

Background:

• Scanning electrochemical microscopy (SECM) and scanning electrochemical cell microscopy (SECCM) are powerful techniques for surface analysis.
• However, each method has limitations that restrict its application scope and performance.
• There is a need for integrated electrochemical probes that overcome these limitations.

Purpose of the Study:

• To design and fabricate a novel coaxial Pt-disk-microelectrode@micropipette probe.
• To integrate the advantages of SECM and SECCM while mitigating their respective disadvantages.
• To evaluate the probe's performance in electrochemical imaging and analysis.

Main Methods:

• Fabrication of a coaxial probe comprising a Pt ultramicroelectrode (UME) and a micropipette.
• Utilizing a stable, renewable nanoliter-scale electrochemical droplet cell.
• Performing optical microscopy, SECM-SECCM measurements, and substrate-generation/tip-collection mode analysis.
• Applying the probe for high-throughput detection of alkaline phosphatase activity and time-since-deposition estimation.

Main Results:

• The probe demonstrated excellent electrochemical performance with a stable, renewable droplet cell.
• Achieved long-term, large-area imaging of conductivity and morphology on diverse dry surfaces.
• Significantly improved spatial resolution and sensitivity in substrate-generation/tip-collection mode.
• Enabled high-throughput detection of alkaline phosphatase activity in blood fingerprints with high accuracy (∼97%) for time-since-deposition estimation.

Conclusions:

• The novel coaxial probe successfully integrates SECM and SECCM capabilities.
• The device offers high sensitivity, high resolution, high throughput, and high accuracy for diverse applications.
• This flexible probe design facilitates advanced electrochemical analysis of surfaces and biological samples.