At the beginning of the project we noticed that the field was still characterized by a few isolated attempts in different laboratories. In order to help shape the field more consistently, the main ideas and perspectives that had been proposed in the recent past were critically curated, underlining what edible electronics is and might be in the future according to our vision [DOI: 10.1002/admt.202000757]. Long-term opportunities (Figure 1) in terms of environmentally friendly smart technologies, remote healthcare monitoring, and the formidable challenges ahead were discussed.
At the end of the project, five years after the initial perspective, we compiled an overview to provide a concrete assessment of the overall progress in edible electronics [manuscript under revision]. Here we noted that the field saw an increase in number of publications per year, clearly boosted by the results obtained in ELFO. Overall, thanks to ELFO and other international groups, many the vision towards future edible systems appears now a more concrete opportunity. While the field is still a niche, it is well differentiated and recognized at international level.
In particular, ELFO gave an important contribution to the:
a) Creation of a broad library of edible and/or non-toxic electronic materials.
Several insulators have been assessed, among which ethyl-cellulose (EC, Figure 2), a food additive, was found to offer good properties for realizing edible substrates. For electronic conductors, we focused on developing edible conducting composites. In particular, we formulated an electrically conductive oleogel paste (Figure 3) made with materials with a high tolerable upper intake limit [DOI: 10.1002/adfm.202113417]. For easing manufacturing, we also demonstrated sprayable and inkjet printable carbon formulations [DOI: 10.1002/adsr.202300150 and 10.1021/acsaelm.4c01509]. For more conductive electrodes, as required in microelectronics, we resorted to inert gold, as those commercialized in the form of edible gold leaves, used for food garnishment. At the same time, we exploited nanoparticles Au inks, which do not require high postprocessing temperatures and are therefore compatible with low thermal budget substrates (Figure 4) [DOI: 10.1039/d3nr01051a]. The need for materials allowing to interconnect components led us to the development of edible electrically conductive adhesive made from corn zein and AC [DOI: 10.1002/smsc.202400373]. In the case of semiconductors, we followed three different strategies, exploring: i) use of biocompatible organic semiconductors not yet tested for edibility and applying in-vitro digestion simulation and cytotoxicity tests on epithelial tissue models [DOI: 10.1002/adfm.202506452]; ii) use of non-toxic pigments approved for cosmetics, such as those contained in toothpastes and inevitably ingested [DOI: 10.1002/advs.202404658] (Figure 5); iii) natural dyes having semiconducting properties [manuscript under revision].
b) Demonstration of several electronic components for future edible electronic systems. ELFO demonstrated low-voltage (< 1 V) organic logic circuits (logic gates, ring oscillators) based on electrolyte-gated field-effect transistors. Such devices share a common architecture made of EC substrate, Au electrodes, chitosan dielectric [DOI: 10.1039/d3nr01051a] and exploit the different strategies for the semiconductor, including CuPc and carotenoids. Several edible sensors were proposed, including: a self-powered edible defrosting sensor (Figure 6) [DOI: 10.1021/acssensors.2c01280] as well as strain [DOI: 10.1002/adsr.202300150] and humidity sensors [DOI: 10.1021/acsaelm.4c01509]. Among different communication strategies options, ELFO focused its effort on Intra-Body Communication (IBC), demonstrated in vitro for the monitoring of passive drug release [DOI: 10.1002/admt.202200731]. One of the best achievements of ELFO was in the development of power supplies: ELFO reported the first example of an edible rechargeable battery (Figure 7) [DOI: 10.1021/acssensors.2c01280].
Communication and Dissemination
Results of ELFO were disseminated in several international conferences, through many invited talks (MRS, EMRS, IEEE FLEPS, IEEE IFETC, SPIE, GRC). Dissemination included visits and communications in internationally recognized institutions, including the University of Cambridge (UK), OnePlanet (Wageningen, NED), UC Santa Barbara (US).
ELFO triggered strong media interest, especially in the case of the release of the edible battery, that was listed in the 2023 best inventions by TIME Magazine, gaining global coverage. The invention of the battery led in 2023 to the innovation award by the Italian young innovators association “ANGI”. Communication to general public included several national events in Italy (Milan Researchers Night, TEDx Rovigo, Maker Fair, to name a few).
Exploitation
Three patent applications were filed. On the basis of this IP basis, an ERC PoC project was submitted. Discussions with potential stakeholders are ongoing. Results and competences developed created very good synergies with other EU projects such as the H2020 FET OPEN “ROBOFOOD” and the MSCA IF “EDISENS”.
