Tag Archives: Michael Dickey

Textiles fight back bacteria with electronics

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These textiles according to an April 24, 2023 news item on SpaceDaily do a little more than fight off bacteria (as impressive as that is),

Scientists from around the world have developed a simple metallic coating treatment for clothing or wearable textiles which can repair itself, repel dangerous bacteria from the wearer and even monitor a person’s electrocardiogram (ECG) heart signals.

Researchers from North Carolina State University [US], Flinders University [Australia] and South Korea [Sungkyunkwan University (SKKU] say the conductive circuits created by liquid metal (LM) particles can transform wearable electronics and open doors for further development of human-machine interfaces, including soft robotics and health monitoring systems.

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An April 25, 2023 Flinders University press release (also on EurekAlert but published April 26, 2023), which originated the news item, provides more technical details about the conductive, self-healing textiles, Note: Links have been removed,

The ‘breathable’ electronic textiles have special connectivity powers to ‘autonomously heal’ itself even when cut, says the US team led by international expert in the field, Professor Michael Dickey.  

When the coated textiles are pressed with significant force, the particles merge into a conductive path, which enables the creation of circuits that can maintain conductivity when stretched, researchers say.   

“The conductive patterns autonomously heal when cut by forming new conductive paths along the edge of the cut, providing a self-healing feature which makes these textiles useful as circuit interconnects, Joule heaters and flexible electrodes to measure ECG signals,” says Flinders University medical biotechnology researcher Dr Khanh Truong, senior co-author in a new article in Advanced Materials Technologies. 

The technique involves dip-coating fabric into a suspension of LM particles at room temperature.  

“Evenly coated textiles remain electrically insulating due to the native oxide that forms on the LM particles. However, the insulating effect can be removed by compressing the textile to rupture the oxide and thereby allow the particles to percolate.  

“This enables the creation of conductive circuits by compressing the textile with a patterned mold. The electrical conductivity of the circuits increases by coating more particles on the textile.”  

As well the LM-coated textiles offer effective antimicrobial protection against Pseudomonas aeruginosa and Staphylococcus aureus.  

This germ repellent ability not only gives the treated fabric protective qualities but prevents the porous material from becoming contaminated if worn for and extended time, or put in contact with other people.    

The particles of gallium-based liquid metals have low melting point, metallic electrical conductivity, high thermal conductivity, effectively zero vapor pressure, low toxicity and antimicrobial properties.  

LMs have both fluidic and metallic properties so show great promise in applications such as microfluidics, soft composites, sensors, thermal switches and microelectronics.  

One of the advantages of LM is that it can be deposited and patterned at room temperature onto surfaces in unconventional ways that are not possible with solid metals. 

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

Liquid Metal Coated Textiles with Autonomous Electrical Healing and Antibacterial Properties (2023) by Jiayi Yang, Praneshnandan Nithyanandam, Shreyas Kanetkar, Ki Yoon Kwon, Jinwoo Ma, Sooik Im, Ji-Hyun Oh, Mohammad Shamsi, Mike Wilkins, Michael Daniele Tae-il Kim, Huu Ngoc Nguyen, Vi Khanh Truong and Michael D Dickey. Advanced Materials Technologies Online Version of Record before inclusion in an issue 2202183 DOI: 10.1002/admt.202202183 First published: 02 April 2023 [2nd DOI:] https://doi.org/10.1002/admt.202202183 

This paper is open access.

Wetware, nanoelectronics and fuel cells

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Some of the computer engineers I worked with years ago used to ‘jokingly’ refer to people as wetware putting us on a continuum with hardware, software, and firmware. Clearly they knew something I didn’t as it seems we’re getting closer to making that joke a reality with the term wetware expanding to include biological systems. Michael Berger in his July 19, 2011 Nanowerk Spotlight essay, Squishy electronics, takes a look at some of the developments in biocompatible electronics [Mar.7.12: duplicate paragraph removed from essay excerpt],

There is a physical and electrical disconnect between the world of electronics and the world of biology. Electronics tend to be rigid, operate using electrons, and are inherently two-dimensional. The brain, as a basis for comparison, is soft, operates using ions, and is three-dimensional. Researchers have therefore been looking to find different routes to create biocompatible devices that work well in wet environments like biological systems.

Berger goes on to highlight some research in North Carolina,

The device fabricated by the NC State team (that included graduate students Ju-Hee So and Hyung-Jun Koo, who also first-authored the paper [research team was led by Orlin Velev and Michael Dickey]) is composed primarily of water-based gels that are, in principle, compatible with biological species including cells, enzymes, proteins, and tissues and thus hold promise for interfacing electronics with biological systems. [emphasis mine]

The novelty of this work is the operating mechanism of the memory device combined with the fact that it is built entirely from materials with properties similar to Jell-O. The memristor-like devices are simple to fabricate and basically consist of two liquid-metal electrodes that sandwich a slab of hydrogel.

This line of work fits in nicely with ‘vampire’ batteries (my latest posting on this topic, July 18k 3011) which can, theoretically, run on blood. Coincidentally, The Scientist  published a June 23, 2011 article,  by Megan Scudellari which focuses on biological fuel cells that can run on bacteria,

This tiny biological fuel cell, the smallest of its kind with a total volume of just 0.3 microliters, was built using microfluidics and relies on bacteria to produce energy. Bacteria colonize the anode, the negatively charged end of the system, and through their natural metabolism produce electrons that flow to the cathode, creating a circuit. Together, the anode and cathode are only a few human hairs wide, but the tiny circuit generates a consistent flow of electricity.

An undated news item on the Carnegie Mellon University website offers this information,

Carnegie Mellon University’s Kelvin B. Gregory and Philip R. LeDuc have created the world’s smallest fuel cell — powered by bacteria.

Future versions of it could be used for self-powered sensing devices in remote locations where batteries are impractical, such as deep ocean or geological environments.

“We have developed a biological fuel cell which uses microbial electricity generation enabled by microfluidic flow control to produce power,” said Gregory, an assistant professor of civil and environmental engineering at CMU.

No bigger than a human hair, the fuel cell generates energy from the metabolism of bacteria on thin gold plates in micro-manufactured channels.

Those injunctions about not mixing liquids with electricity may soon seem a trifle old-fashioned.