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Changing the World through Creative Research

Membrane-less Ionic Liquid Droplet Nanoprobe for Oxygen Sens-ing and Gas Phase Scanning Electrochemical Microscopy


A novel membrane-less oxygen sensing nanoprobe was developed based on a hanging drop ionic liquid electrochemical cell. Ultrasmall (<500 nm) working electrode and small volume electrochemical cell allowed for an impressively low detection limit of ca. 13 ppm and response time less than 100 ms, which is unusually fast for an electrochemical gas sensor. The oxygen sensor was stable for hours of operation, and owing to the membrane-less design, was easily regeneratable when fouled. The pulled capillary form factor of the nanoprobe was found compatible with scanning probe techniques, the demonstration of which was made by application as a tip electrode in gas phase scanning electrochemical microscopy (SECM). In the SECM experiments, the oxygen nanoprobe exhibited micrometer scale spatial resolution with ease. This unique probe design developed here may potentially be engineered into versatile sensors for various volatile molecules other than oxygen pertinent to hazard analysis and biomedical diagnosis.

Anal. Chem. 2022