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Chemistry In Pictures

Chemistry in Pictures: Colorful plasma

by Craig Bettenhausen
July 10, 2024

Three vacuum chambers with little tables inside. From left, they're purple, pink, and violet.
Credit: Submitted by Sina Ardalan

We all know about solids, liquids, and gases from daily life. Plasmas are a more exotic state of matter that most people see only in the form of lightning and the northern lights. Sina Ardalan, on the other hand, works with plasmas on a regular basis in his PhD studies at the University of New Brunswick. Plasma consists of ionized gases, he says, and changing the gases gives the resulting plasmas different properties. Ardalan is developing a surface engineering technique called plasma-activated coating, for making biosensors, that involves flooding a chamber with a sequence of plasmas. “Initially, the purple argon plasma eliminates surface contaminants. Then the pinkish-red plasma mixture of acetylene, nitrogen, and argon gases creates a radical-rich coating layer that allows biomolecules to directly attach to the sensor surface, eliminating the need for expensive or toxic chemical linkers,” he says. The coated part comes out, and a bluish-purple oxygen plasma then cleanses the chamber for the next sample. It sounds complex, but Ardalan says it eliminates the need for multiple wet-chemistry surface prep steps, resulting in a more streamlined fabrication that generates less waste.

Submitted by Sina Ardalan

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