Tag Archives: Warwick University

‘Frozen smoke’ sensors can detect toxic formaldehyde in homes and offices

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I love the fact that ‘frozen smoke’ is another term for aerogel (which has multiple alternative terms) and the latest work on this interesting material is from the University of Cambridge (UK) according to a February 9, 2023 news item on ScienceDaily,

Researchers have developed a sensor made from ‘frozen smoke’ that uses artificial intelligence techniques to detect formaldehyde in real time at concentrations as low as eight parts per billion, far beyond the sensitivity of most indoor air quality sensors.

The researchers, from the University of Cambridge, developed sensors made from highly porous materials known as aerogels. By precisely engineering the shape of the holes in the aerogels, the sensors were able to detect the fingerprint of formaldehyde, a common indoor air pollutant, at room temperature.

The proof-of-concept sensors, which require minimal power, could be adapted to detect a wide range of hazardous gases, and could also be miniaturised for wearable and healthcare applications. The results are reported in the journal Science Advances.

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A February 9, 2024 University of Cambridge press release (also on EurekAlert), which originated the news item, describes the problem and the proposed solution in more detail, Note: Links have been removed,

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Volatile organic compounds (VOCs) are a major source of indoor air pollution, causing watery eyes, burning in the eyes and throat, and difficulty breathing at elevated levels. High concentrations can trigger attacks in people with asthma, and prolonged exposure may cause certain cancers.

Formaldehyde is a common VOC and is emitted by household items including pressed wood products (such as MDF), wallpapers and paints, and some synthetic fabrics. For the most part, the levels of formaldehyde emitted by these items are low, but levels can build up over time, especially in garages where paints and other formaldehyde-emitting products are more likely to be stored.

According to a 2019 report from the campaign group Clean Air Day, a fifth of households in the UK showed notable concentrations of formaldehyde, with 13% of residences surpassing the recommended limit set by the World Health Organization (WHO).

“VOCs such as formaldehyde can lead to serious health problems with prolonged exposure even at low concentrations, but current sensors don’t have the sensitivity or selectivity to distinguish between VOCs that have different impacts on health,” said Professor Tawfique Hasan from the Cambridge Graphene Centre, who led the research.

“We wanted to develop a sensor that is small and doesn’t use much power, but can selectively detect formaldehyde at low concentrations,” said Zhuo Chen, the paper’s first author.

The researchers based their sensors on aerogels: ultra-light materials sometimes referred to as ‘liquid smoke’, since they are more than 99% air by volume. The open structure of aerogels allows gases to easily move in and out. By precisely engineering the shape, or morphology, of the holes, the aerogels can act as highly effective sensors.

Working with colleagues at Warwick University, the Cambridge researchers optimised the composition and structure of the aerogels to increase their sensitivity to formaldehyde, making them into filaments about three times the width of a human hair. The researchers 3D printed lines of a paste made from graphene, a two-dimensional form of carbon, and then freeze-dried the graphene paste to form the holes in the final aerogel structure. The aerogels also incorporate tiny semiconductors known as quantum dots.

The sensors they developed were able to detect formaldehyde at concentrations as low as eight parts per billion, which is 0.4 percent of the level deemed safe in UK workplaces. The sensors also work at room temperature, consuming very low power.

“Traditional gas sensors need to be heated up, but because of the way we’ve engineered the materials, our sensors work incredibly well at room temperature, so they use between 10 and 100 times less power than other sensors,” said Chen.

To improve selectivity, the researchers then incorporated machine learning algorithms into the sensors. The algorithms were trained to detect the ‘fingerprint’ of different gases, so that the sensor was able to distinguish the fingerprint of formaldehyde from other VOCs.

“Existing VOC detectors are blunt instruments – you only get one number for the overall concentration in the air,” said Hasan. “By building a sensor that is able to detect specific VOCs at very low concentrations in real time, it can give home and business owners a more accurate picture of air quality and any potential health risks.”

The researchers say that the same technique could be used to develop sensors to detect other VOCs. In theory, a device the size of a standard household carbon monoxide detector could incorporate multiple different sensors within it, providing real-time information about a range of different hazardous gases. The team at Warwick are developing a low-cost multi-sensor platform that will incorporate these new aerogel materials and, coupled with AI algorithms, detect different VOCs.

“By using highly porous materials as the sensing element, we’re opening up whole new ways of detecting hazardous materials in our environment,” said Chen.

The research was supported in part by the Henry Royce Institute, and the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI). Tawfique Hasan is a Fellow of Churchill College, Cambridge.

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

Real-time, noise and drift resilient formaldehyde sensing at room temperature with aerogel filaments by Zhuo Chen, Binghan Zhou, Mingfei Xiao, Tynee Bhowmick, Padmanathan Karthick Kannan, Luigi G. Occhipinti, Julian William Gardner, and Tawfique Hasan. Science Advances 9 Feb 2024 Vol 10, Issue 6 DOI: 10.1126/sciadv.adk6856

This paper is open access.

Vodka-powered wireless communications featured Canada’s national anthem

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In a joint project between Warwick University (UK) and York University (Canada), researchers sent a text message featuring O Canada (national anthem) in a system that relies on vodka molecules. From the Dec. 18, 2013  news item on Nanowerk,

After successfully text messaging ‘O Canada’ using evaporated vodka, two York University researchers and their UK-based counterpart say their simple system can be used where conventional wireless technology fails.

“Chemical signals can offer a more efficient way of transmitting data inside tunnels, pipelines or deep underground structures. For example, the recent massive clog in London sewer system could have been detected earlier on, and without all the mess workers had to deal with, sending robots equipped with a molecular communication system,” says Professor Andrew Eckford, in whose lab in the Department of Electrical Engineering and Computer Science located in Lassonde School of Engineering, the experiment was conducted.

The Dec. 18, 2013 York University news release (also on EurekAlert), which originated the news item, details how the signaling was achieved (Note: A link has been removed),

The chemical signal, using the alcohol found in vodka in this case, was sent four metres across the lab with the aid of a tabletop fan. It was then demodulated by a receiver which measured the rate of change in concentration of the alcohol molecules, picking up whether the concentration was increasing or decreasing.

“We believe we have sent the world’s first text message to be transmitted entirely with molecular communication, controlling concentration levels of the alcohol molecules, to encode the alphabets with single spray representing bit 1 and no spray representing the bit 0,” says York U doctoral candidate Nariman Farsad, who led the experiment.

Though use of chemical signals is a new method in human communication technology, the biocompatible method is very common in the animal kingdom. Bees for example use chemicals in pheromones when there is a threat to the hive, and so do the Canadian lnyx, when marking territories.

In an article, Tabletop Molecular Communication: Text Messages Through Chemical Signals, in the peer-reviewed journal PLOS ONE, the researchers say their system also fills a major gap in the molecular communication literature, by providing an inexpensive platform for testing theoretical models. This allows researchers to gain real-world experience with molecular communication, cheaply and easily.

“Our system shows that reliable communication is possible and our work motivates future studies on more realistic modelling, analysis, and design of theoretical models and algorithms for molecular communication systems,” says Engineering Professor Weisi Guo at the University of Warwick, who initiated the research during a meeting with Eckford, last year. He adds, “They can also be used to communicate on the nanoscale, for example in medicine where recent advances mean it’s possible to embed sensors into the organs of the body or create miniature robots to carry out a specific task such as targeting drugs to cancer cells.”

York University has also produced a video demonstrating vodka-fueled signaling,

A Dec. 19, 2013 University of Warwick press release provides additional perspective on this achievement (Note: Links have been removed),

Scientists have created a molecular communications system for the transmission of messages and data in challenging environments such as tunnels, pipelines, underwater and within the body.

The technique has a wide range of applications in environments where electromagnetic waves cannot be used, for example in underground structures such as tunnels, pipelines or in underwater environments.

Molecular signalling is a common feature of the plant and animal kingdom – insects for example use pheromones for long-range signalling – but to date continuous data have not been transmitted.

Researchers at the University of Warwick in the UK and the York University in Canada have developed the capability to transform any generic message into binary signals, which in turn is ‘programmed’ into evaporated alcohol molecules to demonstrate the potential of molecular communications. Their results are published in the open access journal PLOS ONE.

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Dr Weisi Guo from the School of Engineering at the University of Warwick said: “Imagine sending a detailed message using perfume – it sounds like something from a spy thriller novel, but in reality it is an incredibly simple way to communicate.

“ Of course people have achieved short ranged signalling using chemicals, but we have gone to the next level and successfully communicated continuous and generic messages over several metres.

For the curious,here’s a link to and a citation for the paper,

Tabletop Molecular Communication: Text Messages through Chemical Signals by Nariman Farsad, Weisi Guo, & Andrew W. Eckford. PLOS ONE Published: December 18, 2013 DOI: 10.1371/journal.pone.0082935

All papers published by PLOS (Public Library of Science) ONE are open access.

One final thought, are the rum-, gin-, ouzo-, whiskey-, tequiila-, etc. lovers going to demand their favourite spirits get equal attention?

Self-assembling and disassembling nanotrain network

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A Nov. 11, 2013 University of Oxford news release (also on EurekAlert dated as Nov. 10, 2013) highlights the first item I’ve seen about a nanostructure which both assembles and disassembles itself,

Tiny self-assembling transport networks, powered by nano-scale motors and controlled by DNA, have been developed by scientists at Oxford University and Warwick University.

The system can construct its own network of tracks spanning tens of micrometres in length, transport cargo across the network and even dismantle the tracks.

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Researchers were inspired by the melanophore, used by fish cells to control their colour. Tracks in the network all come from a central point, like the spokes of a bicycle wheel. Motor proteins transport pigment around the network, either concentrating it in the centre or spreading it throughout the network. Concentrating pigment in the centre makes the cells lighter, as the surrounding space is left empty and transparent.

The researchers have provided an image,

Nanotrain network created by scientists at Oxford University: green dye-carrying shuttles after 'refuelling' with ATP travel towards the center of the network with their cargoes of green dye. Credit: Adam Wollman/Oxford University

Nanotrain network created by scientists at Oxford University: green dye-carrying shuttles after ‘refuelling’ with ATP travel towards the center of the network with their cargoes of green dye. Credit: Adam Wollman/Oxford University

The news release goes on to describe the system,

The system developed by the Oxford University team is very similar [to the melanophore used by fish cells], and is built from DNA and a motor protein called kinesin. Powered by ATP fuel, kinesins move along the micro-tracks carrying control modules made from short strands of DNA. ‘Assembler’ nanobots are made with two kinesin proteins, allowing them to move tracks around to assemble the network, whereas the ‘shuttles’ only need one kinesin protein to travel along the tracks.

‘DNA is an excellent building block for constructing synthetic molecular systems, as we can program it to do whatever we need,’ said Adam Wollman, who conducted the research at Oxford University’s Department of Physics. ‘We design the chemical structures of the DNA strands to control how they interact with each other. The shuttles can be used to either carry cargo or deliver signals to tell other shuttles what to do.

‘We first use assemblers to arrange the track into ‘spokes’, triggered by the introduction of ATP. We then send in shuttles with fluorescent green cargo which spread out across the track, covering it evenly. When we add more ATP, the shuttles all cluster in the centre of the track where the spokes meet. Next, we send signal shuttles along the tracks to tell the cargo-carrying shuttles to release the fluorescent cargo into the environment, where it disperses. We can also send shuttles programmed with ‘dismantle’ signals to the central hub, telling the tracks to break up.’

This demonstration used fluorescent green dyes as cargo, but the same methods could be applied to other compounds. As well as colour changes, spoke-like track systems could be used to speed up chemical reactions by bringing the necessary compounds together at the central hub. More broadly, using DNA to control motor proteins could enable the development of more sophisticated self-assembling systems for a wide variety of applications.

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

Transport and self-organization across different length scales powered by motor proteins and programmed by DNA by Adam J. M. Wollman, Carlos Sanchez-Cano, Helen M. J. Carstairs, Robert A. Cross, & Andrew J. Turberfield. Nature Nanotechnology (2013) doi:10.1038/nnano.2013.230 Published online 10 November 2013

This article is behind a paywall although you can preview it for free via ReadCube Access.

Cold Water Washing Initiative

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Are diamonds going to be everywhere including our clothes detergents? From the June 26, 2012 news item on physorg.com,

Nanodiamonds, pieces of carbon less than ten-thousandths the diameter of a human hair, have been found to help loosen crystallized fat from surfaces in a project led by research chemists at the University of Warwick that transforms the ability of washing powders to shift dirt in eco friendly low temperature laundry cycles.

The June 26, 2012 news release on EurekAlert provides some information about current issues with detergents and coldwater washing,

These new findings tackle a problem that forces consumers to wash some of their laundry at between 60 and 90 degrees centigrade more than 80 times a year. Even with modern biological washing powders, some fats and dirt cannot be removed at the lower temperatures many prefer to use for their weekly wash.

A desire to reduce the significant energy burden of regular high temperature washes, and understand the behaviour of these new materials, brought University of Warwick scientists and colleagues at Aston University together in a project funded by the UK Engineering and Physical Sciences Research Council (EPSRC) and P&G plc.

This “Cold Water Cleaning Initiative” funded a group of chemists, physicists and engineers led by Dr Andrew Marsh in the University of Warwick’s Department of Chemistry to explore how new forms of carbon might work together with detergents in everyday household products.

Here according to researcher Andrew Marsh is what happens when you add nanodiamonds to your detergent/washing powder (from the June 26, 2012 news release),

“We found that the 5 nanometre diamonds changed the way detergents behaved at 25 degrees centigrade, doubling the amount of fat removed when using one particular commercial detergent molecule. Even at temperatures as low as 15 degrees centigrade, otherwise hard-to-remove fat could be solubilised from a test surface. The physical and chemical insight already gained paves the way for future research to explore how this unique behaviour might be exploited in other ways.”

There is no mention of what happens to the clothing when exposed to nanodiamonds in the wash water.