The ability to monitor and control moisture levels with accurate and reliable humidity sensors is essential for efficient manufacturing and storage operations as well as for general well-being.

Now, researchers at the Singapore Institute of Materials Research and Engineering, A*STAR, have designed a fast, low-cost disposable sensor that exploits the unique properties of ultra-thin layers of graphene oxide, or GO, films to monitor humidity levels of ambient air.

Graphene oxide humidity sensor responds to humidity levels by changing colors. Source: American Chemical Society Unlike other humidity sensors that are electronic and require a power supply, GO-based colorimetric sensors respond to humidity levels by changing color, which can be easily observed. For greater accuracy, the change in color can be quantitatively measured by analyzing the reflection spectra of the sensor. Because the GO sensor operates at the atomic level, it can rapidly respond to moisture changes.

“Our research shows for the first time that atomic-scale GO can be used for colorimetric humidity sensors,” said researcher Fuke Wang. “Due to the atomic properties of GO and their hygroscopic nature, the sensor is highly efficient and faster-responding compared with current sensor technologies.”

The low-cost, non-toxicity and rapid response of GO sensors makes them useful as disposable sensors, researchers said. They can be incorporated into food packaging, where humidity levels need to be strictly controlled for storage, for medical instrumentation and semiconducting device manufacturing and storage, as well as environmental monitoring. Their disposal also has no adverse environmental impact.

Further research is underway to adapt the technology to detect other vapors and gasses.