Cheap, light, flexible, and robust circuit boards are essential for wearable electronics, among other applications. In the future, these electronic devices may be printed on flexible circuits made from the bacterial cultures used to make the fermented black tea drink known as kombucha, according to The last paper Published on the arXiv preprint server.

As we reported earlier, the industry of kombucha It only requires combining tea and sugar with the kombucha culture known as a Scooby (symbiotic culture of bacteria and yeast), also known as “mother” – also known as tea fungus, tea fungus or Manchurian mushroom. It’s more like a sourdough starter. SCOBY is a hard, gel-like bundle of cellulose fibers (a biofilm), thanks to which the active bacteria in the culture creates an ideal breeding ground for yeast and bacteria. Dissolve the sugar in boiling dechlorinated water, then steep some tea leaves of your choice in the hot sugar water before discarding.

Once the tea has cooled, add the scoopie and pour everything into a sterilized beaker or jar. Then cover the beaker or jar with a paper towel or cheesecloth to keep insects out, let it sit for two to three weeks, and voila! Have your own home-brewed kombucha. A new Scooby “daughter” will float directly on top of the liquid (known technically in this form as a pellet).

In addition to the beverage’s popularity, kombucha cultures herald it as a beneficial prebiotic. For example, in 2016Young-A Lee, a professor of apparel, merchandising and design at Iowa State, has gained attention for her proof-of-concept research into using desiccant SCOBY as a sustainable alternative to leather for biodegradable clothing, shoes or handbags. In 2021, scientists at MIT and Imperial College London created new types of tough “living materials” that could one day be used as biosensors, helping to purify water or detect damage to “smart” packaging materials. experiments last year A study by researchers at Montana Technological University (MTU) and Arizona State University (ASU) showed that membranes grown from kombucha farms were better at preventing biofilm formation—a major challenge in water filtration—than existing commercial membranes.

“At present kombucha is emerging as a promising candidate for the production of sustainable textiles for use as bio-friendly wearables,” co-author Andrew Adamatsky, from the University of the West of England in Bristol, said in a statement. Tell New Scientist. “We will see that dry – and hopefully live – kombucha mats will be integrated into smart wearable devices that expand the functionality of clothing and gadgets. We propose to develop environmentally friendly smart wearable devices that are a mixture of living and dead biological material.”

Adamatzky previously co-authored a 2021 sheets demonstrating that live kombucha mats exhibited electrodynamic activity and stimulation responses, in addition to a last year’s paper describes the development of a bacterial interactive glove to serve as a live electronic sensor. Inspired by the potential of kombucha mats for wearable electronics, he and his last co-authors have now demonstrated that it is possible to print electronic circuits on desiccant SCOBY mats.

The team used commercially sourced kombucha bacteria to grow their mats, then air-dried them on plastic or paper at room temperature. The mats do not tear easily and are not easily damaged, even when immersed in water for several days. One test mat even survived oven temperatures up to 200 °C (392 °F), although the mats would burn when exposed to an open flame. Adamatsky et al. They were able to print conductive polymer circuits on dried kombucha mats using an aerosol-jet printer, and also successfully tested an alternative method for 3D printing a circuit of a conductive polyester/copper blend. They could even attach small LEDs to the circuits using a silver-toothed epoxy adhesive, which, after being repeatedly bent and stretched, still worked.

According to Adamatsky et al. , unlike the live kombucha mats he had worked with earlier, SCOBY’s desiccant mats are non-conductive, which traps electrical current in the printed circuit. Mats are also lighter, cheaper, and more flexible than ceramic or plastic alternatives. Potential applications include wearable heart rate monitors, for example, and other kombucha-based devices. The authors conclude, “Future research will be interested in printing advanced functional circuits, which are capable of detecting—and possibly recognizing—mechanical, optical, and chemical stimuli.”

DOI: arXiv [preprint]2023. 10.48550 / arXiv.2302.03984 (about DOIs).