Assessing sustainability hotspots in the production of paper-based printed electronics

Abstract

Novel printed electronics are projected to grow and be manufactured in the future in large volumes. In many applications, printed electronics are envisaged as sustainable alternatives to conventional (printed circuit board-based) electronics. One such application is in the semi-quantitative drug detection and point-of-care device called 'GREENSENSE' that uses paper-based printed electronics. This paper analyses the carbon footprint of GREENSENSE in order to identify and suggest means of mitigating disproportionately high environmental impacts, labelled 'sustainability hotspots', from materials and processes used during production which would be relevant in high-volume applications. Firstly, a life cycle model traces the flow of raw materials (such as paper, cellulose nanocrystals, and nanosilver) through the three 'umbrella' processes (circuit printing, component mounting, and biofunctionalization) manufacturing different electronic components (the substrate, conductive inks, energy sources, display, etc.) that are further assembled into GREENSENSE. Based on the life cycle model, life cycle inventories are modelled that map out the network of material and energy flow throughout the production of GREENSENSE. Finally, from the environmental impact and sustainability hotspot analysis, both crystalline nanocellulose and nanosilver were found to create material hotspots and they should be replaced in favor of lower-impact materials. Process hotspots are created by manual, lab-, and pilot-scale processes with unoptimized material consumption, energy use, and waste generation; automated and industrial-scale manufacturing can mitigate such process hotspots.

Steering Innovation toward Sustainable Electrochromic Displays: A Prospective Life Cycle Assessment Study

“…S2 employing two silver-based layers serving as an electrode and counter electrode has the highest environmental impact, attributed to a relatively high silver requirement compared to other ECD configurations (Figure ). Similar to previous environmental research, silver was identified as an environmental hotspot. − The high impact of silver arises from its energy-intensive mining operations that emit significant amounts of greenhouse gases, as well as generating sulfide tailings that can contaminate air, water, and soil and have detrimental effects on human health, thus causing the silver layer in ECD to dominate toxicity-related impacts overshadowing other ECD materials (Figure c,e). Furthermore, silver is a hotspot in the mineral resource scarcity category due to its high depletion potential, given its rarity and cost (Figure d).…”

“…21,25 However, the pretreatment of the paper substrate in specific applications can substantially affect its environmental performance. 22,23 For example, a cellulose nanocrystal-coated paper substrate used in a drug detection device renders the substrate an environmental hotspot. 23 It should be noted that all environmental comparisons of substrates and nanoinks made did not account for the functionality but were compared per single display.…”

“…Only a few studies have performed an environmental assessment on printed electronics, most of which were published after 2020. Studied printed electronic products include antennas, , temperature sensors, solar cells, , printed circuit boards, , drug detection devices, anticounterfeit labels, and shock detection tags . Published LCA studies aimed to identify environmental hotspots in printing materials and determine viable substituents.…”

Advanced Applications of Metal–Organic Decomposition Inks in Printed Electronics

“…37,16 Though silver is currently the most used material to produce conductive traces on PE, it requires up to 72 times more energy to produce in comparison to copper. 39 As such, combinations of copper metal and paper as the substrate could be an excellent combination of materials to consider as environmental impact, sustainability, and recyclability become more of a focus. In this regard, Knapp has recently demonstrated that a copper-based MOD ink can be thermally decomposed at temperatures as low as 150 °C to produce functional conductive traces on paper.…”

“…The incorporation of paper substrates into PE applications has the potential to significantly improve the sustainability of the industry, as it allows for the transition away from petroleum-based substrates toward those derived from a renewable natural resource that is biodegradable and recyclable . A variety of functional devices using silver MOD inks have been demonstrated on biobased substrates, including applications as LED lighting and circuits. , Though silver is currently the most used material to produce conductive traces on PE, it requires up to 72 times more energy to produce in comparison to copper . As such, combinations of copper metal and paper as the substrate could be an excellent combination of materials to consider as environmental impact, sustainability, and recyclability become more of a focus.…”