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Microplasma direct writing for site-selective surface functionalization of carbon microelectrodes
Aung Thiha1,2, Fatimah Ibrahim1,2, Shalini Muniandy2,3
11Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia.
Microsystems & Nanoengineering
|November 23, 2019
Summary
Microplasma direct writing offers a simple method to selectively add oxygen to carbon electrodes, enhancing their performance in biosensors and supercapacitors. This technique improves hydrophilicity and electrochemical properties without complex masks.
Area of Science:
- Materials Science
- Electrochemistry
- Surface Science
Background:
- Carbon micro- and nanoelectrodes made by carbon microelectromechanical systems (carbon MEMS) are vital for biosensors and supercapacitors.
- Surface modification is crucial for improving electrode performance, but conventional methods lack site-selectivity.
- Existing techniques often require complex photoresist masks for targeted surface modification.
Purpose of the Study:
- To introduce microplasma direct writing as a simple, low-cost, and low-power method for site-selective surface functionalization of carbon MEMS electrodes.
- To investigate the effect of water microplasma direct writing on the oxygen content and functional groups of carbon surfaces.
- To evaluate the impact of this surface modification on electrode hydrophilicity and electrochemical performance.
Main Methods:
- Utilized microplasma direct writing with water vapor as an ionic precursor to functionalize carbon MEMS electrodes.
- Generated microplasma discharge between a microelectrode tip and the carbon surface at atmospheric pressure.
- Analyzed changes in surface oxygen content, carbon-to-oxygen ratio, and functional group types (carbonyl, carboxylic, hydroxyl) using surface analysis techniques.
Main Results:
- Microplasma direct writing significantly increased surface oxygen content from ~3% to 27% and reduced the C:O ratio from 35 to 2.75.
- Observed a substantial increase in carbonyl, carboxylic, and hydroxyl functional groups, with carboxylic groups showing the largest increase.
- Demonstrated improved hydrophilicity (contact angle reduced from ~90° to ~20°) and enhanced electrochemical performance (5-fold increase in specific capacitance).
Conclusions:
- Microplasma direct writing is an effective technique for site-selective oxygen functionalization of carbon MEMS electrodes.
- This method offers significant improvements in hydrophilicity and electrochemical properties, crucial for advanced applications.
- The technology provides an accessible and efficient approach for tailoring carbon electrode surfaces for biosensors and supercapacitors.
