Cheap, lightweight, flexible, yet durable printed circuit boards are essential for wearable electronics. According to a recent article published on arxiv.org, its future may be based on flexible circuits created on the basis of bacterial cultures known as kombucha, or kombucha.
A SCOBY (symbiotic culture of bacteria and yeast) creates a dense gel-like mass that is held by the cellulose fibers of the bacteria. In addition to being a popular drink, kombucha cultures promise to become a useful biomaterial.
The authors of the paper, simply titled Kombucha electronics, believe that kombucha may be a promising candidate for the production of eco-friendly textiles for making eco-friendly items on which electronic circuits can be printed.
“We will see dried and hopefully live kombucha mats incorporated into smart wearables that extend the functionality of clothing and gadgets. We propose to develop smart eco-wearable devices that are a convergence of dead and living biological matter,” says Andrew Adamatky from the University of the West of England in Bristol.
Adamatky previously co-authored a 2021 paper demonstrating that living kombucha mats are capable of dynamic electrical activity and stimulatory responses, as well as a paper last year describing the development of a bacterial reactive glove that lives as an electronic sensor device.
The team used commercial kombucha cultures to grow bacterial mats, then dried the resulting products, which were applied to plastic or paper, at room temperature outdoors. The rugs do not tear or deteriorate even when immersed in water for several days. One of the tested rugs withstood the temperature in the oven up to 200°C, although the material ignites when in contact with an open flame.
The researchers were able to print conductive polymer circuits on dried kombucha mats using an aerosol jet printer, and also successfully tested an alternative method of 3D printing circuits from a conductive mixture of polyester and copper. They were able to attach small LEDs to the electrical circuits using silver-filled epoxy. The circuits functioned after being repeatedly bent and stretched.
According to Adamatka, unlike the live kombu mats he’s worked with before, the dried SCOBY mats don’t conduct electricity, limiting its flow to a printed circuit. Mats are lighter, cheaper and more flexible than their ceramic or plastic counterparts. Their potential applications include, for example, the creation of wearable sensors and other devices. Researchers do not stop there:
“Future research will involve printing advanced functional circuits capable of detecting and possibly recognizing mechanical, optical and chemical stimuli.”
Adamatka’s team are not the first researchers of promising biomaterial. Back in 2021, scientists from the Massachusetts Institute of Technology and Imperial College London created new types of durable “living materials” from kombucha, which turned out to be potentially suitable as biosensors to help purify water or signal damage to “smart” packaging materials.
Experiments conducted last year by researchers from Montana Tech University (MTU) and Arizona State University (ASU) showed that membranes grown from kombucha cultures prevented the formation of biofilms, a serious problem in water filtration, better than any industrial counterparts.
In 2016, an Iowa State apparel, merchandising and design professor named Young-E. Lee drew attention for her research that supports the possibility of using dried SCOBY as an eco-friendly leather substitute for biodegradable clothing as well as bags.
Scientists have created electrochemical transistors with a number of unique properties for use in bioelectronics and wearable devices.
Source: Ars Technica
