Carbon Pipette-Based Electrochemical Nanosampler

Sampling ultrasmall volumes of liquids for analysis is essential in a number of fields from cell biology to microfluidics to nanotechnology and electrochemical energy storage. In this article, we demonstrate the possibility of using nanometer-sized quartz pipettes with a layer of carbon deposited on the inner wall for sampling attoliter-to-picoliter volumes of fluids and determining redox species by voltammetry and coulometry. Very fast mass-transport inside the carbon-coated nanocavity allows for rapid exhaustive electrolysis of the sampled material. By using a carbon pipette as the tip in the scanning electrochemical microscope (SECM), it can be precisely positioned at the sampling location. The developed device is potentially useful for solution sampling from biological cells, micropores, and other microscopic objects.