Amazing biomedicine: Liquid metal could make breathable, antimicrobial smart fabrics which could measure heart rate, and even heal itself

Researchers have found a very clever way to coat fabric with a breathable metallic layer that can heal itself, repel bacteria and conduct electricity.

The “liquid metal” coating, described in a paper in Advanced Materials Technologies, could be the basis for smart textiles and wearable electronics.

The international team of researchers say coating is simple: just dip a clean piece of fabric into a liquid for a few seconds. It can be done at room temperature.

Two people in lab holding smart textile and smiling at camera
Dr Vi-Khanh Truong (left), who did textile research in the US, continues the study at Flinders University assisted by biotechnology masters student Tien Thanh Nguyen. Credit: Flinders University

The liquid in question is a solution of the metals gallium and indium, suspended in isopropanol – which is often used in hand sanitisers.

When gallium and indium are combined, they become a liquid at room temperature.

The solution is prepared by sonicating (vibrating with sound) the metals in isopropanol for 45 minutes.

Once dried with a hot-air gun, the metals form tiny drops on the fabric, each a fraction of a micrometre in size.

Co-senior author, Dr Vi Khanh Truong, deputy director of the Biomedical Nanoengineering Laboratory at Flinders University, says the particles look “sort of like blueberries”.

A thin, oxygen-based layer forms on the particles, making them non-conductive.

“But when you press them, you can form a certain conductive pathway,” says Truong.

This means you can build an electronic circuit in the fabric – just by applying enough force to rupture the oxide layer.

“We can customise conductive pathways as we want it,” says Truong.

And by adding more coating, you can make the fabric more conductive.

While neither gallium nor indium are abundant metals, the process needs less than a micrometre of each in its fabric coating.

“So far, it’s quite low cost, because the amount of the material we’re using it quite small,” says Truong.

The conductive pathways can also heal themselves when cut.

Plus, the metals have low toxicity, and are antimicrobial. The researchers showed that the textiles could protect against the infection-causing bacteria Pseudomonas aeruginosa and Staphylococcus aureus in the lab.

Four pictures: one is smart textile with a centimetre scale, one is microscopy image of textile showing bumps with micrometre scale, one is textile being folded and light glowing, one is petri dish with few bacterial colonies on it
Top left: the fabric sample. Top right: fabric at the microscale, with the tiny “blueberries” obvious. Bottom left: the smart textile conducting electricity. Bottom right: the textile’s deleterious effect on bacteria in petri dishes. Credit: Yang et al., 2023, Advanced Materials Technologies, doi: 10.1002/admt.202202183

As well as repelling pathogens, the fabric could be worn for a longer period of time without needing to be washed.

The researchers also made their coated fabric patches into electrocardiograph (ECG) electrodes, and found they performed as well as commercial gel-based electrodes.

Truong says that the textiles could be used in things like antimicrobial hospital bed covers and patient clothing, monitoring heart rate as well as preventing infections.

“The next thing is to, with planning, integrate them into actual textiles,” he says.

The US-based researchers in the team, led by Professor Michael Dickey at North Carolina State University, US, have recently shown that this mixture can be used to make an elastic.

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