This is a nanotorch, which is an ultra-sensitive chemical detector, thanks to its ability to concentrate light. In the intense light fields at the torch’s top, a normally-weak light-based chemical fingerprinting technique (Raman spectroscopy) becomes millions of times stronger. More-sensitive Raman fingerprinting can allow us to detect trace contaminants in water, or to diagnose disease by looking for the presence of telltale molecules in bodily fluids.

And these torches are tiny. At 250 nanometers wide you could fit about 40,000 of them side-by-side across a single kernel of corn.

My former labmate Matthew Chen (now Dr. Matthew Chen) developed the method for making the nanotorches, which involves coating the tops of tiny silica beads with a gold shell and then dissolving away the beads. Once the beads are flipped over, the edges of the gold shell are exposed, which become the rim of the nanotorch.

To me, the torch looks almost organic, like some kind of tiny cup fungus.

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