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Despite advances in soft, sticker‐like electronics, few efforts have dealt with the challenge of electronic waste. Here, this is addressed by introducing an eco‐friendly conductive ink for thin‐film circuitry composed of silver flakes and a water‐based polyurethane dispersion. This ink uniquely combines high electrical conductivity (1.6 × 105 S m−1), high resolution digital printability, robust adhesion for microchip integration, mechanical resilience, and recyclability. Recycling is achieved with an ecologically‐friendly processing method to decompose the circuits into constituent elements and recover the conductive ink with a decrease of only 2.4% in conductivity. Moreover, adding liquid metal enables stretchability of up to 200% strain, although this introduces the need for more complex recycling steps. Finally, on‐skin electrophysiological monitoring biostickers along with a recyclable smart package with integrated sensors for monitoring safe storage of perishable foods are demonstrated. [ABSTRACT FROM AUTHOR]

The Internet of Things (IoT) is gaining more and more popularity and it is establishing itself in all areas, from industry to everyday life. Given its pervasiveness and considering the problems that afflict today's world, that must be carefully monitored and addressed to guarantee a future for the new generations, the sustainability of technological solutions must be a focal point in the activities of researchers in the field. Many of these solutions are based on flexible, printed or wearable electronics. The choice of materials therefore becomes fundamental, just as it is crucial to provide the necessary power supply in a green way. In this paper we want to analyze the state of the art of flexible electronics for the IoT, paying particular attention to the issue of sustainability. Furthermore, considerations will be made on how the skills required for the designers of such flexible circuits, the features required to the new design tools and the characterization of electronic circuits are changing. [ABSTRACT FROM AUTHOR]

The growing usage and consumption of electronics‐integrated items into the daily routine has raised concerns on the disposal and proper recycling of these components. Here, a fully sustainable and green technology for the fabrication of different electronics on fruit‐waste derived paper substrate, is reported. The process relies on the carbonization of the topmost surface of different cellulose‐based substrates, derived from apple‐, kiwi‐, and grape‐based processes, by a CO2 laser. By optimizing the lasing parameters, electronic devices, such as capacitors, biosensors, and electrodes for food monitoring as well as heart and respiration activity analysis, are realized. Biocompatibility tests on fruit‐based cellulose reveal no shortcoming for on‐skin applications. The employment of such natural and plastic‐free substrate allows twofold strategies for electronics recycling. As a first approach, device dissolution is achieved at room temperature within 40 days, revealing transient behavior in natural solution and leaving no harmful residuals. Alternatively, the cellulose‐based electronics is reintroduced in nature, as possible support for plant seeding and growth or even soil amendment. These results demonstrate the realization of green, low‐cost and circular electronics, with possible applications in smart agriculture and the Internet‐of‐Thing, with no waste creation and zero or even positive impact on the ecosystem. [ABSTRACT FROM AUTHOR]

This article presents the realization of a bandpass filter on a flexible biopolymer substrate with a suitable fabrication process. We used copper adhesive tape and laser structuring to fabricate the filter based on a quasi‐lumped microstrip structure. The filter characteristics are a central frequency of 2.45 GHz, a bandwidth of 20%, and insertion loss of 1.2 dB. It is demonstrated that the filter's performance remains almost constant under different bending, folding, and rolling conditions. The results show that the proposed bio‐sourced polymer is a good candidate for flexible green electronics and wearable applications. [ABSTRACT FROM AUTHOR]

Green Electronics In article number 2210422, by using a low‐cost CO2 laser on fruit‐based papers, Giuseppe Cantarella and co‐workers report the fabrication of green and biocompatible electronic devices. The employment of natural and plastic‐free materials gives rise to a sustainable and circular technology, allowing electronics recycling, with no waste creation, and reintroduction in nature. [ABSTRACT FROM AUTHOR]

Keywords: circular and sustainable electronics; flexible electronics; green electronics; healthcare; laser-induced electronics; papers EN circular and sustainable electronics flexible electronics green electronics healthcare laser-induced electronics papers 1 1 1 04/27/23 20230425 NES 230425 B Green Electronics b In article number 2210422, by using a low-cost CO SB 2 sb laser on fruit-based papers, Giuseppe Cantarella and co-workers report the fabrication of green and biocompatible electronic devices. Circular and sustainable electronics, flexible electronics, green electronics, healthcare, laser-induced electronics, papers The employment of natural and plastic-free materials gives rise to a sustainable and circular technology, allowing electronics recycling, with no waste creation, and reintroduction in nature. [Extracted from the article]

There is a strong demand for flexible user interface technology with a desired size and shape to make real world objects touch-interactive. In this regard, plastic based touch sensors have been widely used on account of their adaptability. However, their fabrication involves eco-unfriendly procedures like lithography or other cleanroom processes which contribute greenhouse gases (GHG) and hence raises the need for exploring alternative green fabrication methods. In this work, we report the fabrication of an inexpensive, flexible, biocompatible, low power and environmentally benign interdigitated capacitive (IDC) touch sensor based on cleanroom-free and solvent-free processing of graphite on paper (GOP). The performance of touchpad with four touch sensor keys was evaluated by integrating it with Arduino UNO development board and it functioned similar to the conventional touchpads which are fabricated by utilizing complex procedures and expensive equipments on plastic substrates. The influence of the number and the overlap length of electrode digits on touch sensor performance was investigated and optimized based on variation in capacitance with the interaction of finger with the touch sensor for better performance and enhanced user experience. The pressure due to strength of the touch and strain induced due to bending and folding of the touch sensor resulted in insignificant variation in capacitance and no change in functionality. This suggests that the flexible and robust GOP based touchpad can be used in diverse applications such as user interface for medical diagnostics, health, environment and security monitoring devices where low cost, eco-friendly, flexible, durable and stable touch control is required. This approach of developing highly advanced, efficient yet biodegradable paper electronics which doesn’t involve the use of any toxic, flammable or corrosive gases nor chemicals paves the way for next generation green and sustainable eco-friendly electronics. [ABSTRACT FROM AUTHOR]

This paper aims to demonstrate that novel additive manufacturing (AM) technologies like metal adhesive laminate and multilayer inkjet printing can be effectively exploited to fabricate high-performing radio-frequency passive components on flexible substrates. Both processes are substrate independent and therefore suitable for manufacturing circuits on several unconventional materials, such as photo-paper. In addition, their complementary features can be combined to develop a novel hybrid process. Proof-of-concept AM prototypes of passive components, such as capacitors and inductors, exhibiting quality factors over 70, never achieved before on paper, and self-resonant frequencies beyond 4 GHz are described. The maximum inductance and capacitance per unit area are 1.4 nH/mm2 and 6.5 pF/mm2, respectively. Moreover, an AM RF mixer with a conversion loss below 10 dB is demonstrated still on paper substrate. The mixer, fabricated with the copper adhesive laminate method, operates at 1 GHz and exploits a lumped balun transformer connected to two packaged diodes in series. [ABSTRACT FROM PUBLISHER]

"Green" electronics are increasingly in demand to alleviate environmental pollution caused by electronic wastes. Biomass materials derived from natural resources, such as lignocellulose and chitin, are ideal building blocks for "green" electronics because they are abundant, renewable, biodegradable, thermostable, and can be feasibly modified. However, the complexity in structure and components, inherent hydrophilicity, lack of functionality (e.g., conductivity) of most biomass materials restricts their applications in electronics. To meet the requirement for applications in electronics, designed biomass materials with tailored properties have received considerable attention over the past decade and great progress has been made. This review firstly highlights two main biomass materials: cellulose and chitin. Then, the strategies of designing one-, two- and three-dimensional biomass materials via physical, chemical, biological, and surface- and interface-engineered treatment methods, and the properties of the resulting materials are summarized in detail. After that, recent advances in the use of designed biomass materials to develop "green" electronics, such as organic light-emitting diodes (OLEDs), solar cells (SCs), printed electronics (PEs), and thin-film transistors (TFTs) are reviewed. Finally, an overview of the remaining challenges and perspectives in the field of biomass-based "green" electronics is provided. [ABSTRACT FROM AUTHOR]

A design topology for a microwave planar permittivity sensor focused on manufacturing simplicity is proposed. Its operation is based on the first-notch frequency of the reflection parameter. The impacts of substrate and bending angle on the performance of this type of sensor are comparatively analyzed. Three flexible substrates are considered in comparison to three rigid ones. By full-wave electromagnetic analysis, the sensors have been simulated in contact to a material under test with a relative permittivity ranging between 1 and 20. The resulting shifts in the first-notch frequency show the potential of flexible environmentally-friendly substrates, such as liquid crystal polymer and paper, for the development of the sensors. In the flexible cases, the bending angles have been varied from 0 to 120 ∘ , producing deviations in S 11 first-notch frequency of 0.4 to 4.7%. The simulation methodology is validated by experimental characterization of a prototype on Rogers 4003C laminate. [Display omitted] • Design topology for a microwave planar permittivity sensor focused on geometrical simplicity. • Comparative analysis of the impact of rigid and flexible substrates on sensor performance. • Experimental validation of simulation methodology. • A study on the impact of bending on flexible sensor performance based on electromagnetic analysis. • Design for environmental sustainability. [ABSTRACT FROM AUTHOR]

• CuPc organic films as buffer interlayer to use paper as PCBs is presented for the first time. • The CuPc was synthetized using a new eco-friendly synthetic protocol. • A hybrid touch sensor on paper was successfully demonstrated. • Paper-based capacitors using CuPc work for high frequencies even at high operation voltages. In this work, the use of sublimated copper phthalocyanine (CuPc) organic thin films as a buffer interlayer in aluminum tracks on paper is presented for the first time. The CuPc was synthetized using a new eco-friendly synthetic protocol and the higher purity of the product turn out to be useful for the set forth applications. With the use of the CuPc buffer interlayer it is possible to enable paper substrates as printed circuit boards and as dielectric material for flexible electronic devices. The connectivity of the aluminum tracks was evaluated when the paper substrate is bent several times and after ten months of storage at ambient conditions. In addition, the aluminum tracks exhibit reliable current driving capabilities to turn-on a LED device. Finally, the fabrication of a hybrid touch sensor on paper is demonstrated. [ABSTRACT FROM AUTHOR]

Paper is a flexible material, commonly used for information storage, writing, packaging, or specialized purposes. It also has strong appeal as a substrate in the field of flexible printed electronics. Many applications, including safety, merchandising, smart labels/packing, and chemical/biomedical sensors, require an energy source to power operation. Here, progress regarding development of photovoltaic and energy storage devices on cellulosic substrates, where one or more of the main material layers are deposited via solution processing or printing, is reviewed. Paper can be used simply as the flexible substrate or, exploiting its porous fiber‐like nature, as an active film by infiltration or copreparation with electronic materials. Solar cells with efficiencies of up to 9% on opaque substrates and 13% on transparent substrates are demonstrated. Recent developments in paper‐based supercapacitors and batteries are also reviewed with maximum achieved capacity of 1350 mF cm−2 and 2000 mAh g−1, respectively. Analyzing the literature, it becomes apparent that more work needs to be carried out in continuing to improve peak performance, but especially stability and the application of printing techniques, even roll‐to‐roll processing, over large areas. Paper is not only environmentally friendly and recyclable, but also thin, flexible, lightweight, biocompatible, and inexpensive. [ABSTRACT FROM AUTHOR]