A Fully Edible Transistor Based on a Toothpaste Pigment

Edible electronics is emerging in recent years motivated by a diverse number of healthcare applications, where sensors can be safely ingested without the need for any medical supervision. However, the current lack of stable and well-performing edible semiconductors needs to be addressed to reach technological maturity and allow the surge of a new generation of edible circuits. In the quest for good-performing edible semiconductors, this study has explored the possibility of considering materials that are not regulated for intentional ingestion, yet are daily swallowed with no adverse reactions, such as pigments contained in toothpaste. This work first elaborates on the basis of inadvertent ingestion data to estimate the quantity of daily ingested Copper(II) Phthalocyanine (CuPc), a whitening pigment and well-known organic semiconductor. Subsequently, CuPc is employed in the first demonstration of fully edible electrolyte-gated transistors operating at low voltage (<1 V), displaying good reproducibility and stable performance for over a year. The results indicate that, with the daily ingested quantity of CuPc from toothpaste, more than 10⁴ edible transistors can be realized, thus paving the way to edible circuits, a critical component of future edible electronic systems.