Edible toothpaste-based transistors

The toothpaste-based transistor is the latest innovation from a team of researchers at the Italian Technical Institute in Milan. Credit: IIT-Istituto Italiano di Tecnologia
The toothpaste-based transistor is the latest innovation from a team of researchers at the Italian Institute of Technology (IIT) in Milan who are pushing the boundaries of edible electronics. The revolutionary nanodevice is expected to be a key component of future smart pills designed to monitor health from within the body and dissolve safely once it has performed its function. The findings were published in the journal Advanced Science.
Many commercial toothpastes contain crystals of copper phthalocyanine, a blue pigment that acts as a whitening agent by adhering to the teeth and acting as an optical filter to make the teeth appear whiter.
Copper phthalocyanine is gradually excreted and ingested through saliva throughout the day. A research team from the IIT Center for Nano Science and Technology (CNST) in Milan (Italy) in collaboration with dental researchers from the University of Novi Sad in Serbia investigated the properties of this substance. Through laboratory simulations and the analysis of existing clinical data, they found that on average, humans unconsciously ingest about one milligram of copper phthalocyanine every time they brush their teeth.
“With the amount of copper phthalocyanine that we consume every day, we could theoretically produce around 10,000 edible transistors,” said lead author Elena Feltri, a doctoral student at the Indian Institute of Technology CNST in Milan.
Indeed, what makes this pigment interesting is its chemical structure that facilitates charge conduction within the crystal, making copper phthalocyanine an ideal candidate as a semiconductor for organic electronics applications.


Commercial toothpaste formulas contain crystals of copper phthalocyanine, a blue pigment that acts as a whitening agent. The researchers incorporated small amounts of this new ingredient, which acts as a semiconductor, into a recipe for making edible circuits that have already been tested. Credit: IIT-Istituto Italiano di Tecnologia
The team incorporated small amounts of this new material as a semiconductor into a previously tested recipe for building edible circuits: The circuits were built on an ethyl cellulose substrate, and the electrical contacts were printed using inkjet technology and a solution of gold particles, a material often used to decorate food.
The “gate” made from an electrolytic gel based on chitosan (a food-grade gelling agent extracted from crustaceans such as blue crabs) allows the transistor to operate at low voltages of less than 1V.
The edible transistor was developed at the Institute of Printed and Molecular Electronics, led by Mario Caironi, and follows on from the edible battery invented by the same group last year. Caironi’s laboratory is dedicated to studying the electronic properties of food and its derivatives, with the aim of developing edible electronic devices that could in future be applied in healthcare and quality control in the food industry. In addition, since 2021 his team has been participating in the European Robofood project, which aims to develop edible robots.
The research group’s next step is to identify other edible substances with suitable chemical and physical properties to create intelligent edible electronics for healthcare applications, such as monitoring body parameters in the digestive tract.
Further information: Elena Feltri et al. “Fully edible transistors based on toothpaste pigments.” Advanced Science (2024). DOI: 10.1002/advs.202404658
Courtesy of Italian Institute of Technology
Source: Edible Toothpaste-Based Transistor (September 26, 2024) Retrieved September 26, 2024 from https://phys.org/news/2024-09-edible-toothpaste-based-transistor.html
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