Tag Archives: airport security

Terahertz imagers at your fingertips

It seems to me that I stumbled across quite a few carbon nanotube (CNT) stories in 2018. This one comes courtesy of Japan (from a June 28, 2018 news item on Nanowerk),

Researchers at Tokyo Tech have developed flexible terahertz imagers based on chemically “tunable” carbon nanotube materials. The findings expand the scope of terahertz applications to include wrap-around, wearable technologies as well as large-area photonic devices.

Here’s a peek at an imager,

Figure 1. The CNT-based flexible THz imager (a) Resting on a fingertip, the CNT THz imager can easily wrap around curved surfaces. (b) Just by inserting and rotating a flexible THz imager attached to the fingertip, damage to a pipe was clearly detected. Courtesy Tokyo Tech

A June 28, 2018 Tokyo Tech Institute press release (also on Eurekalert), which originated the news item, provides more detail,

Carbon nanotubes (CNTs) are beginning to take the electronics world by storm, and now their use in terahertz (THz) technologies has taken a big step forward.

Due to their excellent conductivity and unique physical properties, CNTs are an attractive option for next-generation electronic devices. One of the most promising developments is their application in THz devices. Increasingly, THz imagers are emerging as a safe and viable alternative to conventional imaging systems across a wide range of applications, from airport security, food inspection and art authentication to medical and environmental sensing technologies.

The demand for THz detectors that can deliver real-time imaging for a broad range of industrial applications has spurred research into low-cost, flexible THz imaging systems. Yukio Kawano of the Laboratory for Future Interdisciplinary Research of Science and Technology, Tokyo Tech, is a world-renowned expert in this field. In 2016, for example, he announced the development of wearable terahertz technologies based on multiarrayed carbon nanotubes.

Kawano and his team have since been investigating THz detection performance for various types of CNT materials, in recognition of the fact that there is plenty of room for improvement to meet the needs of industrial-scale applications.

Now, they report the development of flexible THz imagers for CNT films that can be fine-tuned to maximize THz detector performance.

Publishing their findings in ACS Applied Nano Materials, the new THz imagers are based on chemically adjustable semiconducting CNT films.

By making use of a technology known as ionic liquid gating1, the researchers demonstrated that they could obtain a high degree of control over key factors related to THz detector performance for a CNT film with a thickness of 30 micrometers. This level of thickness was important to ensure that the imagers would maintain their free-standing shape and flexibility, as shown in Figure 1 [see above].

“Additionally,” the team says, “we developed gate-free Fermi-level2 tuning based on variable-concentration dopant solutions and fabricated a Fermi-level-tuned p-n junction3 CNT THz imager.” In experiments using this new type of imager, the researchers achieved successful visualization of a metal paper clip inside a standard envelope (see Figure 2.)

Non-contact, non-destructive visualization

Figure 2. Non-contact, non-destructive visualization

The CNT THz imager enabled clear, non-destructive visualization of a metal paper clip inside an envelope.

The bendability of the new THz imager and the possibility of even further fine-tuning will expand the range of CNT-based devices that could be developed in the near future.

Moreover, low-cost fabrication methods such as inkjet coating could make large-area THz imaging devices more readily available.

1 Ionic liquid gating

A technique used to modulate a material’s charge carrier properties.

2 Fermi level

A measure of the electrochemical potential for electrons, which is important for determining the electrical and thermal properties of solids. The term is named after the Italian–American physicist Enrico Fermi.

3 p-n junction

Refers to the interface between positive (p-type) and negative (n-type) semiconducting materials. These junctions form the basis of semiconductor electronic devices.

Here’s a link to and a citation for the paper,

Fermi-Level-Controlled Semiconducting-Separated Carbon Nanotube Films for Flexible Terahertz Imagers by Daichi Suzuki, Yuki Ochiai, Yota Nakagawa, Yuki Kuwahara, Takeshi Saito, and Yukio Kawano. ACS Appl. Nano Mater., 2018, 1 (6), pp 2469–2475 DOI: 10.1021/acsanm.8b00421 Publication Date (Web): June 6, 2018

Copyright © 2018 American Chemical Society

This paper is behind a paywall.

Detecting dangerous liquids in airline luggage with a Josephson junction; NANOvember in Albany, New York; nano haiku for November

To be free of those clear plastic bags which hold all your bottles of liquids when you go through airport security with your luggage! That is a very worthwhile nanotechnology promise. From the news item on Nanowerk,

Restrictions on liquids in carry-on bags on commercial airliners could become a thing of the past thanks to a revolutionary nano-electric device which detects potentially hazardous liquids in luggage in a fraction of a second, according to a team of German scientists. Writing in the journal Superconductor Science and Technology, the researchers at the Forschungszentrum Juelich in western Germany claim that they have been able to do this using an optical approach that detects all existing and future harmful liquids within one fifth of a second.

Since the paper has been published, the researchers have been approached by industrial partners about producing a prototype. (sigh) Most likely this means they hope it will be about five years before we see the devices in airports. The device itself is known as a Josephson junction and you can read more about it on the Azonano site too.

I am happy to see that the College of Nanoscale Science and Engineering (CNSE) at the University of Albany (New York, US) has held a remarkably successful nano event, Community Day, during NANOvember  attracting about 1000 people.  From the news item on Nanowerk,

NANOvember is part of “NEXSTEP,” or “Nanotechnology Explorations for Science, Training and Education Promotion,” a partnership between CNSE and KeyBank. Spearheaded by CNSE’s Nanoeconomics Constellation, the initiative features a variety of educational programs designed to promote greater understanding of the changing economic and business environment in the Capital Region and New York State being driven by nanotechnology. “As nanotechnology increasingly shapes the educational and economic landscapes of the Capital Region, NANOvember offers a platform through which the community can better understand the impact and opportunities driven by this emerging science,” said Jeffrey Stone, president, Capital Region, KeyBank N.A.

I’m impressed they attracted that large a crowd in a city with a population of about 100,000 (Albany county has a population of about 300,000) according the 2000 census statistics. By contrast, the city of Vancouver (Canada) has a population of about 600,000 with a regional population of approximately 2 million (from the City of Vancouver website on November 9, 2009) and I’m hard pressed to recall either of our local universities claiming a similar success for one of their community days.

One other point about Albany and nanotechnology, in a July 2008 posting I noted a $1.5B investment for a research centre  in Albany, NY, being made by IBM. So this nanotechnology communication/education event seems to dovetail very nicely with past occurrences and suggests an overall strategy is at work.

Some haiku from NISEnet’s (Nanoscale Informal Science Education Network) newsletter,

After you read this
Your finger nail will have grown
a nanometer
by Troy Dassler

We struggle to show
The size of a molecule.
Kids wait patiently.

by Mike Falvo

You can check out the organization’s The Nano Bite blog here.