Laser-cooling method could reduce size of medical devices

Developed over three years at Nanyang Technological University (NTU) in Singapore, the new method could be applied to many systems that require cooling, such as MRI machines, night-vision goggles and satellite cameras.

This discovery is published in the 24 January 2013 issue of Nature.

During the research, assistant professor Xiong Qihua from the School of Physical and Mathematical Sciences and the School of Electrical and Electronic Engineering cooled down a semiconductor from +20ºC to -20ºC.

The material — cadmium sulphide — is a type of group II-VI semiconductor commonly used in solar cells, sensors and electronics.

‘If we are able to harness the power of laser cooling, it would mean that medical devices that require extreme cooling — such as MRI, which uses liquid helium — could do away with their bulky refrigerant systems with just with an optical refrigeration device in its place,’ Xiong said in a statement.

‘Not only that, but it would also remove the need for compressors and coolants in air conditioning and refrigerators used in our homes and automobiles, saving space, energy and greenhouse gases, which are harmful to our ozone layer.’

According to Global Industry Analysts, the global market for energy-efficient buildings is estimated to be worth more than $100bn (£63.4bn) by 2017, increasing the potential for a compact, cost-effective, vibration-free and cryogen-less cooling system.

Xiong added: ‘This also translates into the ability to build miniaturised coolers to cool infrared sensors used in satellites for imaging and to build self-cooling computer chips suitable for use in portable devices such as tablets and smartphones.’

Xiong is now said to be looking to bring laser cooling down to liquid-helium temperature at -269ºC.

‘Our initial results… have shown that it is possible to laser-cool a semiconductor to liquid-nitrogen temperature, so we are aiming to reach an even lower temperature, such as that of liquid helium,’ he said.