Chitosan-gated organic transistors printed on ethyl cellulose as a versatile platform for edible electronics and bioelectronics.

Edible electronics is an emerging research field targeting electronic devices that can be safely ingested and directly digested or metabolized by the human body. As such, it paves the way to a whole new family of applications, ranging from ingestible medical devices and biosensors to smart labelling for food quality monitoring and anti-counterfeiting. Being a newborn research field, many challenges need to be addressed to realize fully edible electronic components. In particular, an extended library of edible electronic materials is required, with suitable electronic properties depending on the target device and compatible with large-area printing processes, to allow scalable and cost-effective manufacturing. In this work, we propose a platform for future low-voltage edible transistors and circuits that comprises an edible chitosan gating medium and inkjet-printed inert gold electrodes, compatible with low thermal budget edible substrates, such as ethylcellulose. We report the compatibility of the platform, characterized by critical channel features as low as 10 µm, with different inkjet-printed carbon-based semiconductors, including biocompatible polymers present in the picogram range per device. A complementary organic inverter is also demonstrated with the same platform as a proof-of-principle logic gate. The presented results offer a promising approach to future low-voltage edible active circuitry, as well as a testbed for non-toxic printable semiconductors.

Sweet Electronics: Honey-Gated Complementary Organic Transistors and Circuits Operating in Air.

Sustainable harnessing of natural resources is key moving toward a new-generation electronics, which features a unique combination of electronic functionality, low cost, and absence of environmental and health hazards. Within this framework, edible electronics, of which transistors and circuits are a fundamental component, is an emerging field, exploiting edible materials that can be safely ingested, and subsequently digested after performing their function. Dielectrics are a critical functional element of transistors, often constituting their major volume. Yet, to date, there are only scarce examples of electrolytic food-based materials able to provide low-voltage operation of transistors at ambient conditions. In this context, a cost-effective and edible substance, honey, is proposed to be used as an electrolytic gate viscous dielectric in electrolyte-gated organic field-effect transistors (OFETs). Both n- and p-type honey-gated OFETs (HGOFETs) are demonstrated, with distinctive features such as low voltage (<1 V) operation, long-term shelf life and operation stability in air, and compatibility with large-area fabrication processes, such as inkjet printing on edible tattoo-paper. Such complementary devices enable robust honey-based integrated logic circuits, here exemplified by inverting logic gates and ring oscillators. A marked device responsivity to humidity provides promising opportunities for sensing applications, specifically, for moisture control of dried or dehydrated food.