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The global overabundance of electronic waste and ever‐increasing concerns regarding the energy‐and material‐intensive manufacturing processes associated with traditional electronics are driving the development of solution‐processed, degradable electronics. Of note, the industry‐dominating prevalence of harmful lead‐based materials in sensing and actuating devices drives the push for more eco‐friendly solution‐processed piezoelectric systems. Yet current ecofriendly multi‐material printing processes are limited by both the conventional challenges of multilayer processes as well as the low‐temperature thermal constraints of biodegradable materials. Herein, a novel approach for fabricating fully printed, sustainable piezoelectric transducers on paper substrates is presented. Low‐temperature screen‐printing processes are used to integrate non‐toxic KNbO3 layers with degradable carbon‐ or zinc‐based conductive inks into devices. The influence of electrode material on device characteristics is assessed, with effective piezoelectric coefficients reported as high as 4.6 pC N−1 and 5.1 pC N−1 for devices with carbon and zinc electrodes respectively. The potential of the developed technology is then demonstrated through the first‐ever instance of fully printed piezoelectric force sensors and acoustic speakers comprised entirely of green materials. By demonstrating entirely printable green piezoelectric devices compatible with various electrode materials, this work serves as a step towards developing more complex sustainable piezoelectric technologies in the future. [ABSTRACT FROM AUTHOR]

Termites are insects that can damage buildings, paper and plants. Termites are controlled by using termiticides (chemicals). Besides polluting the environment, termiticides may have harmful effects to organisms, including humans, and destroy metal. The use of chemicals will be environmentally and economically profitless. A joint effort to utilize biodegradable material will help to reduce the negative impacts of termiticides. One of the materials that can use to control termites is chitosan. The purpose of this study was to determine the termiticidal activity of chitosan on paper against termites. The termiticidal activity test followed method JIS K 1571 2004. The resistance of paper to termite damage was determined by calculating the percentage of weight loss and termite mortality rate. The following concentrations of chitosan in acetic acid were used: 0.5%, 1%, 1.5% and 2%. The test result showed that weight loss percentages were 20.49%, 16.37%, 15.77% and 10.80%, respectively. On the other hand, the weight loss percentage of paper without chitosan was 32.69%, which shows that termites do not favour chitosan used in the paper. The activity of termites was successfully inhibited when the concentration of chitosan was increased, and the percentage of paper weight loss decreased from 10.80% to 20.49%. Paper without chitosan had a termite mortality rate of 18.3%; The addition of chitosan increased termite mortality to 28.2%-30.4%. The percentage of weight loss decreased with increasing termite mortality. The termite mortality rate show that chitosan is nontoxic and potential as biotermiticide for paper. [ABSTRACT FROM AUTHOR]

Paper-basedpentacene organic thin-film transistors (OTFTs) with spin-coated gelatin (G) stacked gate dielectric layers, the Au/pentacene/G/G matrix-embedded iron (FeG)/Al/paper structure, were fabricated. The proposed composite-stacked bio-dielectric layer can be implemented using solutions with the degradable biomaterials. These materials enable a large-area printing of use-and-throw devices. Control devices (Au/pentacene/G/Al and Au/pentacene/FeG/Al structure) were also fabricated for comparison. High-performance paper-based OTFT constructed from the stacked gate dielectric layer exhibited a carrier mobility of 8 cm2/Vs, an ON/OFF current ratio of approximately 103, a subthreshold swing of 0.6 V/decade, and a threshold voltage of −1.4 V. These results are compatible to those OTFTs fabricated on other substrates. Therefore, the emerging biomaterial-based transistors on paper substrates may help in developing low-cost, environment-friendly devices. [ABSTRACT FROM AUTHOR]

Globe Thistles-Like NiCo 2 S 4 and rGO grow on flexible paper for the detection of H 2 O 2. [Display omitted] • To paper as the basement, successfully developed a low cost and biodegradable flexible electrochemical sensor electrode materials. • NiCo 2 S 4 microspheres with unique globe thistles-like structure was prepared for the first time. • The NiCo 2 S 4 /rGO/FP electrode has high sensitivity, low LOD, and wide linear range. The Globe Thistles-Like (GTL) NiCo 2 S 4 nanostructures were supported on reduced graphene oxide modified filter paper (FP). The prepared GTL NiCo 2 S 4 /rGO/FP is investigated as a disposable and flexible electrode for the electrochemical detection of H 2 O 2 in alkaline media. Owing to the rich redox active sites, the synergistic effect between Co3+ and Ni2+, and the rapid electron transportation of substituting sulfur (S) for oxygen (O) in NiCo 2 O 4 , the GTL NiCo 2 S 4 /rGO/FP exhibits considerable enzyme-free H 2 O 2 sensing performance with wide linear H 2 O 2 ranging from 38.8 to 37306.8 μM, high sensitivity of 2.4326 mA mM−1 cm−2, and low detection limit of 0.08 μM. The GTL NiCo 2 S 4 /rGO/FP electrode has stable sensing performance and is highly selective toward analyte for physiological interfering species. The excellent electrochemical performance of GTL NiCo 2 S 4 /rGO/FP composite is attributed to the GTL structure of NiCo 2 S 4. By studying the hydrothermal reaction time, electrochemical active surface area, and hydrophilic-hydrophobic surfaces of GTL NiCo 2 S 4 /rGO/FP composite, the relationship between the microstructure and sensing performance of the composite was elucidated. Surely this study opens up new possibilities for the application of low-cost, biodegradable flexible electrode materials in wearable sensors in the near future. [ABSTRACT FROM AUTHOR]

Paper-based materials have attracted a great deal of attention in sensor applications because they are readily available, biodegradable, inexpensive, and mechanically flexible. Although paper-based sensors have been developed, but important obstacles remian, which include the retention of chemical and mechanical stabilities when paper is wetted. Herein, we develop a simple and scalable process for fabrication of newspaper-based platforms by coating of parylene C and patterning of metal layers. As-prepared parylene C-coated newspaper (PC-paper) provides low-cost, disposable, and mechanically and chemically stable electrochemical platforms for the development of potentiometric ion sensors for the detection of electrolyte cations, such as, H + and K + . The pH and K + sensors produced show near ideal Nernstian sensitivity, good repeatability, good ion selectivity, and low potential drift. These disposable, flexible ion sensors based on PC-paper platforms could provide new opportunities for the development of point-of-care testing sensors, for diagnostics, healthcare, and environment testing. [ABSTRACT FROM AUTHOR]

Paper, a cheap and ubiquitous material, has great potential to be used as low-cost, portable and biodegradable platform for chemical and biological sensing application. In this paper, we are exploring a low-cost, flexible and reliable method to effectively pattern paper for capturing optical dyes and for flow-based delivery of target samples for colorimetric chemical sensing. In this paper, we target the detection of ammonia (NH 3 ) and carbon dioxide (CO 2 ), two of the important environmental and health biomarkers. By functionalizing the paper platform with diverse cross-reactive dyes sensitive to NH 3 and CO 2 , their selective sensing within a certain pH range, as well as their detection at different concentrations can be achieved. The images of paper based device were captured by a flatbed scanner and processed in MATLAB ® using a RGB model and PCA for quantitative analysis. Paper based devices with readout using ubiquitous consumer electronic devices (e.g. smartphones, flatbed scanner) are considered promising approaches for disease screening in developing countries with limited resources. [ABSTRACT FROM AUTHOR]

[Display omitted] • Reproducible sensors using biodegradable substrates and eco-friendly materials. • Use of cost-effective techniques for their fabrication. • Simplified layout for the joint measurement of RH and temperature on the same IDES. Given the increasing number of connected devices as a consequence of the Internet of Things (IoT) revolution, the issue of the removal and recycling of electronics is becoming more and more urgent. In this context, biodegradable electronics is expected to be one of the biggest technological revolutions to tackle this problem. Following this direction, in this work we present the fabrication and characterization of temperature and humidity sensors based on biodegradable materials with the goal of making their removal easier as well as reducing their environmental impact. In particular, these multi-sensing devices were fabricated following a screen-printing process using a carbon-based paste and a conjugated polymer, both on paper and on a water soluble substrate. The results are more than promising and show how with our biodegradable sensors it is possible to obtain a sensitivity of 1 dec/20%RH to moisture content and around 0.04%/°C sensitivity to temperature. It is demonstrated that the simplicity and flexibility of the fabrication approach followed in this work paves the way to a set of new "green" IoT nodes that could be extended to wide range of sensing applications. [ABSTRACT FROM AUTHOR]