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This article was originally published in German as a press release by RADICAL partner Helmholtz-Zentrum Dresden-Rossendorf (HZDR) on 06/04/2022. Auto-translation into English by Google Translate.

HZDR team reaches first milestone for development of highly sensitive nanosensors.

The World Health Day 2022 “Our planet, our health” draws attention to the health consequences of climate change. Many effects are not yet sufficiently understood. The EU-funded RADICAL project could provide an important piece of the puzzle. Innovative sensor technology should allow continuous monitoring of free radicals in the atmosphere for the first time. A research team at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) has now taken the first fundamental step: the production of tailor-made nanowire chips with special sensor properties.

Free radicals affect our air quality, environment, climate and health. But to what extent? New sensors from the European RADICAL project could soon answer this question. So far, the detection of free radicals has been technically extremely complex and their measurement has been the exception. In the future, the new sensor technology could monitor free radicals in the atmosphere in real time and thus create reliable data to better assess their impact on our health and the environment.

“Electronic nose”

At the heart of the technology are chips just a few square millimeters in size, made of so-called transition-free nanowire transistors. Unlike conventional nanowire transistors, these devices work without a barrier layer between differently structured semiconductor materials. As a result, they achieve, among other things, a particularly good signal-to-noise ratio: an important prerequisite for detecting volatile radicals. As part of an “electronic nose”, the nanowires generate electrical signals at the slightest contact with a suitable target molecule by means of an additional, specific coating. Readout electronics process the signals further – similar to how the human brain processes olfactory stimuli and recognizes and differentiates between smells.

Over the past twelve months, the Dresden researchers have optimized the properties of the nanowire chips for use in the new sensors. In order for the transistors to process signals with sufficient sensitivity and without interference, the wires, which are just a few nanometers thick, must have particularly smooth surfaces and ideal geometric properties. For the optimal design, the researchers use simulations provided by Smartcom, a RADICAL industrial partner in Bulgaria.

“The HZDR laboratory is one of the few laboratories in the world that can precisely manufacture such thin nanowires. With the delivery of the first chips, we have reached the first technical milestone. Now our partners in Cork and York can tackle the functionalization of the components and carry out the first tests on the sensors,” says Dr. Yordan Georgiev, one of the initiators of the RADICAL project and head of nanofabrication at HZDR. 

At the same time, he and his colleagues are further optimizing the manufacturing process and preparing to test the sensors in gaseous media.

Yordan Georgiev, EBL lab. Credit: HZDR

Inexpensive and flexible sensor chips

The expectations of the new sensors are high, because some of the RADICAL research partners already used similar nanowire chips in liquids a few years ago. “At that time we were able to show that we can achieve outstanding sensitivity and selectivity,” says Georgiev. Building on this, the researchers decided to test the highly sensitive technology in gases as well. And on particles that are particularly difficult to detect there: free radicals.

In the future, the new electronic sensors should be so cost-effective and flexible that they could easily be integrated into existing, globally distributed measuring stations for monitoring air quality and the atmosphere. In the long term, the sensors could also be adapted for other applications and, in addition to radicals, also detect other gases in the ambient air with high sensitivity and thus contribute to maintaining our health.

RADICAL is an EU-funded research project developing innovative sensors for detecting free radicals in the atmosphere. The multidisciplinary RADICAL consortium includes University College Cork (Ireland), HZDR (Germany), University of York (UK), National Technical University of Athens (Greece), Smartcom (Bulgaria) and UCC Academy (Ireland) as well an external consultant to Airlabs (UK).

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