An edible toothpaste-based transistor

A toothpaste-based transistor is the latest innovation from the research team at the Istituto Italiano di Tecnologia (IIT-Italian Institute of Technology) in Milan, which pushes the boundaries of edible electronics. This innovative nano-device is expected to become a key component of future smart pills, designed to monitor health conditions from within the body and then safely dissolve after completing their function.

Several commercial toothpaste formulations contain crystals of copper phthalocyanine, a blue pigment that acts as a whitening agent. This substance is deposited on the teeth, functioning as an optical filter to enhance their whiteness.

Throughout the day, copper phthalocyanine is gradually removed by saliva and ingested. The research team at IIT's Center for Nano Science and Technology (CNST) in Milan (Italy) investigated the properties of this substance in collaboration with a dental researcher from the University of Novi Sad in Serbia. Through laboratory simulations and analysis of existing clinical data, they determined that, on average, humans inadvertently ingest about 1 milligram of copper phthalocyanine each time they brush their teeth.

"With the amount of copper phthalocyanine we ingest daily, we could theoretically manufacture approximately 10,000 edible transistors," says Elena Feltri, the paper's lead author and a doctoral student at IIT's CNST in Milan. Actually, an intriguing aspect of this pigment is its chemical structure, which facilitates charge conduction within its crystals, making copper phthalocyanine an excellent candidate for use as a semiconductor in organic electronics applications.

Image source: IIT-Istituto Italiano di Tecnologia.