Microwave-Absorbing Sheets Make Mobile Phones Safer

For release 28 February 2001

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Materials scientists at the Hong Kong University of Science and Technology (HKUST) have successfully developed a microscopic, super thin and low-cost protective film that can absorb a significant portion of the microwave radiation from mobile phone.

The research was undertaken by Assistant Professor Weijia Wen, Professor Ping Sheng, and Associate Professors Weikun Ge and Che Ting Chan from the Department of Physics.

It is still unknown whether exposure to electromagnetic fields (EMFs) from mobile phones causes adverse health hazards. Studies have linked mobile phones to dizziness, nasal bleeding, vomiting, Alzheimer’s disease, brain tumors and cancers. No conclusion, however, has been drawn. A precautionary approach is therefore recommended until scientific evidence on the possible health impacts becomes available. Health experts advise consumers to buy handsets which emit less EMFs, and suggest that children and adolescents minimize their use of mobile phones.

Current mobile phone systems operate at frequencies between 900 MHz and 1900 MHz. Metal covers make unsuitable radiation shields because they add weight to the mobile phone handsets. Mirror reflection with the antenna also causes interference in communication.

To overcome these problems, the HKUST research team has employed absorption technology to replace the reflection model described above. The ultra-thin protective film, made up of a nano-structured composite material, absorbed more than 50% of EMFs at 900 MHz and up to 70% or more at 1800 MHz during laboratory testing. Transmisson and reflection are small as the effect of the EMFs is dominated by absorption. The higher the level of EMFs, the more absorbent the film will be. As frequencies of 3G (third generation) handsets are often as high as 2200 MHz, the performance of the film in absorbing EMFs will be higher.

Dr Weikun Ge explains that EMFs are stronger when you make outgoing calls than when you receive calls. However, using the protective film to shield the front part of the antenna facing the head protects the brain from EMFs without interfering with the quality of signal transmission.

“We believe the protective film is an ideal material for protection against EMFs from mobile phones. It is easy to produce, and cheap, amounting to only a few Hong Kong dollars in production cost. It poses minimal interference to communication and helps to protect the human brain,” explains Dr Weijia Wen.

An added advantage is its flexibility: it can be installed inside the handset or used as a shield on the mobile phone, providing both convenience and safety to users.

For media enquiries only: Jacky Tsang

Tel: 2358-6306 email: patsang@ust.hk