Today's electronics are manufactured to provide stable functionality and fixed physical forms optimized for reliable operation over long periods and repeated use. However, even when applications don't call for such robustness, the permanency of these electronics comes with environmental consequences. In this paper, we describe an alternative approach that utilizes sustainable transient electronics whose method of destruction is also key to their functionality. We create these electronics through three different methods: 1) by inkjet printing conductive silver traces on poly(vinyl alcohol) (PVA) substrates to create water-soluble sensors; 2) by mixing a conductive beeswax material configured as a meltable sensor; and 3) by fabricating edible electronics with 3D printed chocolate and culinary gold leaf. To enable practical applications of these devices, we implement a fully transient and sustainable chipless RF detection system.

Advances in manufacturing methods for electronics most often aim to produce highly integrated and reliable devices for long-term use. While these features have brought benefits to customers, they also have many side effects. One of these is e-waste, which is the fastest-growing waste stream in the world with 53.6 Mt. (million metric tonnes) generated in 2020. Significant effort has been put toward e-waste recycling, but the composition of electronic devices makes the recycling process far more challenging than that of other materials like metals and cardboard.

The goal of this work is to explore transiency as an alternative to traditional electronics. Transient electronics are designed with destruction in mind. That is to say, the disposal of the hardware is integral and intrinsic to its design. In this schema, a device exists for only as long as it's needed. Given this, transient electronics naturally have a place in our future; however, less explored is how such electronics can enable interactivity, what HCI researchers can do with them, and how sustainable materials may be utilized to deliver all this. We examine these questions by utilizing well-understood materials — ones that are known to researchers, practitioners, and designers alike for more traditional uses — in the new context of enabling interaction in sustainable transient electronics. Some of these materials, like polyvinyl alcohol (PVA) or carbon powder, are often overlooked as possible solutions for sustainable transiency because they so often are part of more traditional electronic systems. That is to say, they are not always sustainable when used in their more traditional contexts. For others, their sustainability is impacted by their supply chain. Wax, for example, is not inherently unsustainable; while paraffin wax is traditionally the result of a crude oil-intensive process, its sustainable alternative, beeswax, is the natural byproduct of honey bees.

In this project, we have investigated how materials, fabrication tools and methods, and different types of destruction (melting, dissolving, etc.) can be combined to make devices with sustainability, transiency, and interactivity at the core. We introduce three practical approaches for building such devices, all of which are accessible to HCI researchers, and many of which are highly manufacturable. Our methods include inkjet printing conductive traces on water-soluble PVA sheets, laser-transferring edible gold foil onto 3D printed chocolates, and fabricating electronic devices using natural beeswax. We demonstrate applications of these methods which take advantage of each material's physical transiency for functional goals. For example, water-soluble electronics that can be used for water-leakage sensing, edible chocolate electronics which destroy data contained in a circuit through digestion, and beeswax-based temperature sensors which melt away after use. Lastly, we implemented a metallic resonator design in all three material systems enabling fully passive and chipless RF detection in each context. Such chipless RFID technology requires no soldering process or non-recyclable components and allows each of these embodiments to interact with other systems.