The microchips have an insulating base made of non-recyclable plastic: researchers have replaced it with the biodegradable skin of a mushroom, obtaining promising results.
Every year, the world produces around 50 million tons of electronic waste, including mobile phone and computer chips and microchips that consist mainly of a cooling and insulating base, called substrate, made of non-recyclable plastic polymers. A team of Austrian researchers has discovered that the skin of a wood fungus can be a biodegradable and resistant replacement for plastic, allowing them to produce more environmentally friendly and recyclable chips.
The fungus is Ganoderma lucidum, a parasitic fungus that grows in oak or chestnut wood. It develops a skin that protects its vegetative apparatus, the mycelium, from bacteria and other fungi. This skin, which does not grow in other fungi, when extracted and dried is flexible, insulating and resistant (it tolerates temperatures above 250 °C), and has a thickness similar to that of a sheet of paper.
All of these are ideal properties for the substrate of an electronic circuit. If kept away from sources of moisture and UV light, leather could probably last hundreds of years. At the same time, it can decompose in the soil in as little as two weeks, which facilitates its recycling. The tests showed that the conductive capacity of such skin is almost equal to plastic polymers normally used in chips: the fungal substrate also maintains its properties even after folding it more than two thousand times.
The bio substrate could find several applications, from wearable devices used in medical technology to monitor the health of patients, to batteries powering low-power devices such as bluetooth sensors or RFID tags.
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