Scientists at the National Institute of Standards and Technology (NIST) just figured out how to make a highly specialized light sensor 100 times larger than before. If you want to study deep space or track blood flow inside the human body, catching faint light is incredibly important. Here is how they did it.

Photo: Natasha Hanacek/NIST

The Problem With Tiny Wires

For years, researchers have used devices called superconducting nanowires to catch individual particles of light, known as photons. These devices use super-cold wires that carry electricity with absolutely zero resistance.

When a photon hits the wire, it acts like a rock hitting a river. It creates a tiny hot spot, or a splash, which disrupts the flow of electricity. A computer reads that disruption as a signal.

But there was a catch. To make sure the tiny photon actually disrupted the current, scientists believed the wire had to be microscopic. If the wire were too wide, the splash would not be big enough to register. Because these wires were nanoscale, they required very low electric currents. This meant that low-energy photons barely made a splash, making them incredibly difficult to detect. Tiny wires are also notoriously difficult to manufacture, and they tend to produce false signals.

Using Magnets To Even The Flow

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The NIST team found a clever workaround. They added superconducting “rails” along the edges of the central wire. These rails run current in the same direction, generating a magnetic field.

When the magnetic field from the rails meets the magnetic field of the wire, it forces the electric current to flow perfectly evenly. There is no more current building up just on the edges of the wire. By smoothing the flow, the team maximized the current the wire could carry.

This simple change allowed them to widen the wire to a tenth of a millimeter. That might sound small to you, but it is more than 100 times wider than the old nanoscale versions. Now, even a very faint photon creates a clear, measurable splash.

Better Tools For Medicine And Space

Making the sensor wider solves two big problems. First, a bigger target catches more photons. Second, a larger architecture makes it much easier to build sensors on a commercial scale.

This is a big deal for healthcare. Doctors use a technique called diffuse correlation spectroscopy to measure blood flow. They shine a faint beam of light through human tissue and catch the scattered light that bounces back. A bigger, more sensitive detector makes this process much more accurate. It also helps astronomers who rely on catching faint, low-energy light to study distant galaxies.

Engineers still need to do more testing to see if these supersized detectors are as perfectly efficient as the tiny ones, but the early results show a lot of promise.