New sensor made out of hydrogels can detect mysterious substances

Researchers developed a new sensor that can respond to the environment and detect small changes in pH levels. It can detect glucose levels in blood, for instance.

Researchers at Purdue University created a diffraction-based sensor that can accurately detect chemicals and biological material in the environment.

The sensor is made out of a polymer called a hydrogel. It can detect the pH level of the surrounding liquid, and therefore reveal the identity of the substance-in-question. The hydrogel can expand or contract and it is pretty sensitive to the environment. All these characteristics make it a good sensor.

When the material was originally discovered five decades ago, the researchers described it as muscles flexing.

Check out the picture to see how the hydrogels swell up as the pH level changes.

You're already familiar with this principle, as contact lenses and disposable diapers expand when put in a liquid environment. Although in this case, the hydrogel was made to be water-insoluble except for a certain pattern of stripes. It's the striped areas that are used to detect any changes in the environment.

Again, the sensors are very sensitive. On the pH scale of 0 to 14, the sensor can detect changes smaller than one-1,000th on the pH scale.

Purdue engineering professor Cagri Savran said in a statement:

By precise measurement of pH, the diffraction patterns can reveal a lot of information about the sample environment. This technology detects very small changes in the swelling of the diffraction grating, which makes them very sensitive.

This kind of sensor could be used to keep an eye on waterways or to detect glucose levels in blood, the researchers said. What's next? The scientists are working on making the sensors even more sensitive than they are.

Savran, again:

As with any novel platform, more development is needed, but the detection principle behind this technology is so simple that it wouldn't be difficult to commercialize.

Photo: Birck Nanotechnology Center, Purdue University

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