Researchers at Osaka University have developed a paper-based disposable gas sensor which reportedly addresses supply chain issues such as the cost and sustainability of the raw materials used, the robustness and consistency of the devices, and their disposability and environmental impact.
The sensor is made from very fine nanowires that are supported by a biodegradable cellulose nanofiber backing and have graphite electrodes that can be drawn on with a pencil. The sensor was used to detect NO2 gas—an important component of many industrial processes—and showed a performance comparable to that of available electrodes.
“Our design ticks many boxes for delivering economical and environmentally conscious molecular sensing on a large scale,” explained Osaka University researcher Hirotaka Koga. “The zinc oxide nanowires offer a very large surface area for gas molecules to attach to, and the cellulose paper support is robust and can be cut very small—to just a few millimeters—with ordinary scissors. The sensors are prepared in a simple 2-step process, which makes them appropriate for widespread use.”
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When NO2 molecules are present around the sensor they adsorb to the surface of the nanowires, and the resistance increases as the gas molecules affect the electrons that carry current between the electrodes. The resistance increase is greater for more concentrated gas.
“We expect the many advantages of our device to make a significant contribution, particularly to molecular detection,” noted Associate Professor Koga. “The accurate measurement of gas concentrations is important in many fields including healthcare, environmental protection, chemical production and health and safety.”
The researchers hope that the simple two-step process can be extended to detect other gas molecules.