Thermomechanical micromachine detects T-rays


The terahertz radiation (THz) is one of the most promising areas of current research, with applications ranging from healthcare to the ultra - efficient magnetic recording data.

These T-rays are not yet being used on a large scale because the sources for their emission and the antennas for their detection are still being improved.

Ya Zhang, from the University of Tokyo, has now made a remarkable breakthrough in this area.

It has developed a microelectromechanical device ( MEMS ) that detects terahertz radiation at room temperature, is easy to use, much faster than conventional thermal sensors, is highly sensitive and can be incorporated into detector arrays to increase efficiency.

The small terahertz antenna detects the T rays using the change in the mechanical resonance frequency of a tiny suspended beam, a change caused by thermal expansion generated by THz radiation. It operates at room temperature, while similar devices require cryogenic temperatures of up to -270 ° C.

This breakthrough can unleash a new era of terahertz technologies, such as sensors and cameras, including medical imaging - T-rays allow imaging of the interior of the human body without the use of ionizing radiation, such as X-rays.

Terahertz antenna

The MEMS (microelectromechanical system) consists of a small beam suspended over an opening. The beam is coated with a resistive metal film (NiCr - nickel - chromium) that has the ability to absorb THz radiation, which in turn transfers heat to the beam. This increase in temperature causes the beam to expand very slightly, which can be detected as a change in the frequency with which it vibrates.

This MEMS-based approach has a number of advantages over existing alternatives for detecting THz radiation. The ability to operate at room temperature without the need for cooling makes the sensor suitable for a variety of practical applications. It is also extremely sensitive by detecting radiation that causes changes in temperature to only one millionth of a degree centigrade and offering a reading 100 times faster than other prototypes.

"Another advantage of this system is that it can be produced using standard methods to make semiconductor devices, which will potentially allow them to be incorporated into mass-produced THz based cameras and sensors," said Ya Zhang. "We hope that our work will lead to an explosion of interest and more innovation in this field."


 Fast and sensitive bolometric terahertz detection at room temperature through thermomechanical transduction

 Ya Zhang, Suguru Hosono, Naomi Nagai, Sang-Hun Song, Kazuhiko Hirakawa

 Journal of Applied Physics 
Vol. 125, Issue 15
 DOI: 10.1063 / 1.5045256

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