Source: The Engineer.

Handheld medical scanners reminiscent of Star Trek ¡¯tricorders¡¯ could be a step closer thanks to a new way of producing terahertz radiation.

Researchers from the UK and Singapore have used nanotechnology to create stronger directional beams of the terahertz ¡¯T-rays¡¯ that are used in full-body security scanners, and produce them at room temperature.

The scientists from Imperial College London and Singapore¡¯s Agency for Science, Technology and Research (A*STAR) say this could allow future T-ray systems to be smaller, cheaper, more portable and easier to operate than existing devices.

¡®The fact that we have enhanced the power by more than a factor of 100 means better energy efficiency [and] quicker scanning speed for imaging or screening applications,¡¯ Imperial¡¯s Prof Stefan Maier told The Engineer.

Nanoscale antenna

T-rays are electromagnetic waves from the far-infrared part of the spectrum that are used in security scanners for detecting explosives or drugs and spectroscopy systems for materials analysis and non-destructive testing of microchips.

They can also detect biological phenomena such as increased blood flow around tumourous growths and identify molecules in living DNA.

But current methods for producing T-rays require very low temperatures and high energy consumption, and existing medical T-ray imaging devices have only low output power and are expensive.

Nano-scale electrodes form an antenna that amplifies the terahertz radiation.

The new technique involves creating a nanoscale antenna that amplifies the T-rays as they are generated. This is formed from two metal electrodes separated by a 100nm gap on a semiconductor wafer that uses light pulses and a powerful current to create the radiation.

Maier said:¡®We use electrodes with a nanoscale gap between them in order to enhance both the pumping visible light pulses that generate the terahertz radiation and the terahertz radiation emerging from that gap. Previously, electrodes with a much bigger gap have been used.¡¯

Electron beam lithography

Fabricating the antenna requires a technique called electron beam lithography in order to make the very small gaps in the electrodes, and the scientists would need to find a way to mass-produce them. Maier said this could be done with nano-imprint lithography.

He added that other applications for the more powerful T-rays could include scanning for biomaterials such as plastic explosives and disease agents, and other medical scanning such as screening melanoma-suspicious skin moles.

Various technologies are being researched that could lead to the development of a tricorder-like device that could perform everything from the spectroscopic analysis of airborne molecules to microfluidic DNA sequencing.

The X Prize Foundation, with sponsorship from Qualcomm, is offering $10m (£6.5m) to the creators of a handheld device that can best diagnose a set of diseases.

The research was led by scientists from A*STAR¡¯s Institute of Materials Research and Engineering (IMRE), and Imperial College London, and published in the journal Nature Photonics.

It was funded by A*STAR¡¯s Metamaterials Programme and the THz Programme, as well as the Leverhume Trust and the Engineering and Physical Sciences Research Council (EPSRC) in the UK.