Scientists from Italy and Serbia have built a transistor from copper phthalocyanine (CuPc), a well-known component that is used in whitening toothpaste but can also be used as an organic semiconductor. The substance remains stable for more than a year and can operate as an electrolyte-controlled transistor at less than 1 V—and is safe for human consumption.
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By brushing your teeth twice a day, a person takes in about 1 mg of CuPc, which is 12,500 times more than the 80 nanograms (ng) needed to create the chip. The edible transistor will prove useful in developing medical devices that can be safely ingested to study the gastrointestinal tract. For example, capsule endoscopy—swallowing a tiny, wireless camera the size of a tablet—requires physician supervision and the examination is visual only.
Edible transistors will help in the development of more complex devices, such as sensors for assessing the levels of enzymes and other chemicals. Such devices do not pose a significant health risk, which means they can be used without training or medical supervision. This can be useful in earlier diagnosis of diseases and even automation of treatment procedures.
Previously, scientists have proposed other edible electronic components: electrolytes, batteries, supercapacitors, conductive pastes and inks, and sensors – but their use would be limited without transistors to act as the “brains” of the operation. A CuPc transistor may be a relatively simple and inexpensive solution to this problem.