Aerogels for electromagnetic wave absorption
Modern electronic devices emit EMWs that can disrupt nearby equipment and pose health risks, including DNA damage and cancer. It is critical, therefore, to develop materials that can effectively absorb EMWs to shield both humans and infrastructure from these adverse effects. Applications include enhancing the privacy and security of buildings as well as protecting sensitive medical equipment.
To address this need, Assoc Prof Duong’s team has developed a scalable and eco-friendly procedure to produce novel aerogels that are effective at EMW absorption. The process involves blending three main components – carbon nanotubes, polyvinyl alcohol and carboxymethyl cellulose – followed by freeze-drying.
The aerogel, with a thickness of about 3 millimetres – roughly the width of 40 strands of human hair – demonstrated an impressive performance of absorbing 99.99 per cent of EMW energy. Across the entire X-band (8.2-12.4 GHz) of the electromagnetic spectrum, used primarily for radar systems, weather monitoring and air traffic control, the aerogel consistently showed its ability to absorb 90 per cent of EMW energy.
“In addition to offering a wide absorption bandwidth of 1.2-2.2 GHz in the X-band, our aerogel is also about 10 times lighter than existing composites used for EMW absorption,” added Assoc Prof Duong. “Unlike other composites, our aerogel requires no mixing with heavy polymer fillers before use.”
The researchers have estimated that producing one square-metre of the aerogel, with a thickness of one centimetre, costs less than S$100. This cost is substantially lower than the price of other similar commercial materials, which could range from S$180 to above S$1,000.
Looking ahead, the team plans to refine the aerogel’s mechanical properties, such as flexibility, to broaden their applicability across various building and infrastructure projects. The researchers also aim to conduct real-world tests to fully assess the EMW absorption capabilities of the aerogels in practical scenarios.