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Extensive research into green technologies is driven by the worldwide push for eco‐friendly materials and energy solutions. The focus is on synergies that prioritize sustainability and environmental benefits. This study explores the potential of abundant, non‐toxic, and sustainable resources such as paper, lignin‐enriched paper, and cork for producing laser‐induced graphene (LIG) supercapacitor electrodes with improved capacitance. A single‐step methodology using a CO2 laser system is developed for fabricating these electrodes under ambient conditions, providing an environmentally friendly alternative to conventional carbon sources. The resulting green micro‐supercapacitors (MSCs) achieve impressive areal capacitance (≈7–10 mF cm−2) and power and energy densities (≈4 μW cm‐2 and ≈0.77 µWh cm−2 at 0.01 mA cm−2). Stability tests conducted over 5000 charge–discharge cycles demonstrate a capacitance retention of ≈80–85%, highlighting the device durability. These LIG‐based devices offer versatility, allowing voltage output adjustment through stacked and sandwich MSCs configurations (parallel or series), suitable for various large‐scale applications. This study demonstrates that it is possible to create high‐quality energy storage devices based on biodegradable materials. This development can lead to progress in renewable energy and off‐grid technology, as well as a reduction in electronic waste. [ABSTRACT FROM AUTHOR]

Laser-induced graphene (LIG) is as a promising material for flexible microsupercapacitors (MSCs) due to its simple and cost-effective processing. However, LIG-MSC research and production has been centered on non-sustainable polymeric substrates, such as polyimide. In this work, it is presented a cost-effective, reproducible, and robust approach for the preparation of LIG structures via a one-step laser direct writing on chromatography paper. The developed strategy relies on soaking the paper in a 0.1 M sodium tetraborate solution (borax) prior to the laser processing. Borax acts as a fire-retardant agent, thus allowing the laser processing of sensitive substrates that other way would be easily destroyed under the high-energy beam. LIG on paper exhibiting low sheet resistance (30 Ω sq−1) and improved electrode/electrolyte interface was obtained by the proposed method. When used as microsupercapacitor electrodes, this laser-induced graphene resulted in specific capacitances of 4.6 mF cm−2 (0.015 mA cm−2). Furthermore, the devices exhibit excellent cycling stability (> 10,000 cycles at 0.5 mA cm−2) and good mechanical properties. By connecting the devices in series and parallel, it was also possible to control the voltage and energy delivered by the system. Thus, paper-based LIG-MSC can be used as energy storage devices for flexible, low-cost, and portable electronics. Additionally, due to their flexible design and architecture, they can be easily adapted to other circuits and applications with different power requirements. [ABSTRACT FROM AUTHOR]

Since the discovery of laser-induced graphene (LIG), significant advances have been made to obtain green LIG (gLIG) from abundant, eco-friendly, natural, and organic renewable bio-based carbon sources. Recently, some sustainable and cost-effective electronic devices have been designed with gLIG, resulting in diverse solutions to the environmental impact caused by electronic waste (e-waste). However, there are still several challenges that must be addressed regarding the widespread market implementation of gLIG-based products, from synthesis to practical applications. In this review, we focus on sustainable precursor sources, their conversion mechanisms, physical and chemical properties and applications, along with the challenges related to its implementation, showing the future opportunities and perspectives related to this promising new material. Various systems based on gLIG for energy storage, electrocatalysis, water treatment, and sensors have been reported in the literature. Additionally, gLIG has been proposed for ink formulation or incorporation into polymer matrices, to further expand its use to non-carbon-based substrates or applications for which pristine LIG cannot be directly used. In this way, it is possible to apply gLIG on diverse substrates, aiming at emerging wearable and edible electronics. Thus, this review will bring an overview of gLIG developments, in accordance with the European Green Deal, the United Nations Sustainable Development Goals and the new era of internet-of-things, which demands cost-effective electronic components based on the principles of energy efficiency and sustainable production methods. [ABSTRACT FROM AUTHOR]

Laser irradiation to induce networks of graphene-based structures toward cost-effective, flexible device fabrication is a highly pursued area, with applications in various polymeric substrates. This work reports the application of this approach toward commonly available, eco-friendly, low-cost substrates, namely, chromatographic and office papers. Through an appropriate chemical treatment with sodium tetraborate as a fire-retardant agent, photothermal conversion to porous laser-induced graphene (LIG) on paper is achieved. Raman peaks are identified, with I2D/IG and ID/IG peak ratios of 0.616 ± 0.095 and 1.281 ± 0.173, showing the formation of multilayered graphenic material, exhibiting sheet resistances as low as 56.0 Ω sq-1. Coplanar, LIG-based, three-electrode systems (working, counter and reference electrodes) are produced and characterized, showing high current Faradaic oxidation and reduction peaks, translating in high electrochemical active area, doubling the geometric area. Good electron transfer kinetics performed exclusively with on-chip measurements are reached, with k0 values as high as 7.15 x 10-4 cm s-1. Proof-of-concept, amperometric, enzymatic glucose biosensors are developed, exhibiting good analytical performance in physiologically relevant glucose levels, with results pointing to the applicability of paper-based LIG toward efficient, disposable electrochemical sensor development, increasing their sustainability and accessibility, while simplifying their production and reducing their cost. [ABSTRACT FROM AUTHOR]

Monitorization of gait‐related parameters is of the utmost importance to prevent complications in several diseases, ensuring affordable healthcare for the growing amount of chronic, lifestyle‐related diseases and also for improving motion performance. Sensorized insoles allow to both pressure data and gait timings to be extracted non‐intrusively in a point of care paradigm. Laser‐induced graphene (LIG) offers a path to the integration of sensors in different kinds of materials, including cork, a common insole material. In this work, piezoresistive sensors are developed by providing conductivity to natural cork and agglomerate cork through the direct synthesis of LIG by UV irradiation. Highly isotropic conductive LIG regions with less than 100 Ω sq−1 are patterned and their piezoresistive response for up to 1132 kPa is assessed with sensitivities up to 0.02 kPa−1. A low‐cost prototype insole is devised and tested, proving the potential of this kind of functional cork as a green alternative for gait analysis platforms. [ABSTRACT FROM AUTHOR]

When thinking on low cost and sustainable electronic systems, paper can be considered as an interesting option to be used as substrate but also as a component of such systems. In this work we have tailored paper samples that were used simultaneously as physical support and dielectric in oxide based paper field effect transistors (FETs). It was observed that the gate leakage current in these devices depends directly from fibril's dimension and arrangement, being lower for micro/nano fibrillated cellulose paper. Moreover, extra ionic charge added to the paper during its production results in the improvement of FETs' electrical properties, with saturation mobility of 16 cm 2V -1s -1 and on/off current ratio close to 105. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Laser‐induced graphene (LIG) can be obtained by irradiation of a polymer by a laser source. The present work demonstrates that it is possible to obtain this kind of material using an ultraviolet laser instead of the typical infrared source. Using this approach, a fourfold decrease in the penetration depth (5 µm) is achieved, while the spatial resolution is doubled. Electromechanical strain LIG sensors are patterned in polyimide substrates with different thicknesses and their performance to strain, bending, and force inputs is measured. A low‐cost arterial pulse wave monitor is built, exploring the high force sensitivity of the sensors produced on the thinner substrates. Laser‐induced graphene is obtained by irradiation of polyimide by an ultraviolet laser instead of the typical infrared source, with a fourfold decrease in the penetration depth and doubled spatial resolution. Electromechanical strain sensors are patterned in substrates with different thicknesses and their performance is measured. A low‐cost arterial pulse wave monitor is built, exploring the higher sensitivity of thinner substrates. [ABSTRACT FROM AUTHOR]

Laser-induced graphene from paper (paper-LIG) was applied in non-enzymatic electrochemical sensing of uric acid (UA) in human urine. Paper-LIG was formed by CO 2 laser modification of paper into a 3D graphene arrangement. Kinetic analysis of paper-LIG electrodes returned effective heterogeneous electron transfer standard rate constants of 1.4 × 10−3 cm s−1 and 7.8 × 10−4 cm s−1 for [Ru(NH 3) 6 ]2+/3+ and [Fe(CN) 6 ]4−/3− redox probes, respectively. These electrodes were able to detect and quantify uric acid in PBS within the 10–300 μM range at pH between 5.6 and 7.4. At pH 7.4, a linear response (R2 = 0.999) from 10 to 250 μM was achieved, with a limit of detection of 3.97 μM and a sensitivity of 0.363 μA cm−2 μM−1. Paper-LIG electrodes denoted adequate selectivity in synthetic urine as well as in ascorbic acid (AA) and dopamine (DA)-containing electrolytes. Determination of urinary UA content in human samples returned a concentration of c.a. 1.8–1.9 mM, within the range for healthy individuals. Recoveries of samples spiked with 50 and 100 μM UA were 100.6% and 95.4%, respectively, with satisfactory reproducibility and stability. These cheap, lightweight, flexible, and eco-friendly paper-LIG biosensors for non-enzymatic quantification of UA in human urine pave the way to widespread application in the detection of other important biomarkers. [Display omitted] • "Green" graphene electrodes by CO 2 laser irradiation of paper ("paper-LIG"). • Uric acid (UA) quantification at clinically relevant concentrations and pH (5.6–7.4). • Limit of detection of 3.97 μM and a sensitivity of 0.363 μA cm−2 μM−1 (pH = 7.4). • Adequate selectivity in synthetic urine, as well as in ascorbic acid and dopamine-containing electrolytes. • Recoveries of 100.6% and 95.4% for human urine samples spiked with 50 and 100 μM UA. [ABSTRACT FROM AUTHOR]

Abstract Graphene has emerged as a novel material with enhanced electrical and structural properties that can be used for a multitude of applications from super-capacitors to biosensors. In this context, an ultra-sensitive biosensor was developed using a low-cost, simple and mask-free method based on laser-induced graphene technique for electrodes patterning. The graphene was produced on a polyimide substrate, showing a porous multi-layer structure with a resistivity of 102.4 ± 7.3 Ω/square. The biosensor was designed as a 3-electrode system. Auxiliary and working electrodes were made of graphene by laser patterning and the reference electrode was handmade by casting a silver ink. A molecularly-imprinted polymer (MIP) was produced at the working electrode by direct electropolymerization of eriochrome black T (EBT). As proof-of-concept, the MIP film was tailored for chloramphenicol (CAP), a common contaminant in aquaculture. The resulting device was evaluated by cyclic voltammetry and electrochemical impedance spectroscopy readings against a redox standard probe. The limit of detection (LOD) was 0.62 nM and the linear response ranged from 1 nM to 10 mM. These analytical features were better than those produced by assembling the same biorecognition element on commercial graphene- and carbon-based screen-printed electrodes. Overall, the simplicity and quickness of the laser-induced graphene technique, along with the better analytical features obtained with the graphene-based electrodes, shows the potential to become a commercial approach for on-site sensing. Highlights • Ultra-sensitive graphene-based biosensor developed by a low cost and mask-free method using laser-induced graphene technique. • Detection of chloramphenicol with a LOD of 0.62 nM. • Combination of molecularly-imprinting technology with laser-induced graphene. • Promising approach for future quantitative biosensing. [ABSTRACT FROM AUTHOR]

Laser-induced graphene (LIG) is a foam-like porous material consisting of few-layer graphene obtained by laser irradiation of a wide range of carbon-containing substrates. Among these, the ability to synthesize LIG from paper and other cellulose-related materials is particularly exciting, as it opens the door to a wide assortment of potential applications in the form of low-cost, flexible, and biodegradable devices. Here, the synthesis of this material, dubbed paper-LIG , on different types of filter papers and xylan biopolymer is discussed. In particular, we report the formation of paper-LIG by single-step irradiation, providing an improvement over the conventional multiple lasing approach and giving an explanation of the conditions that allow this simplified synthesis. All the relevant process parameters are covered, assessing their effect on the resulting electrical properties, structure, and morphology. Additionally, we demonstrate the application of LIG obtained from xylan, an abundant and often underutilized biopolymer, for temperature sensing. These results provide a better understanding of the conditions required for the synthesis of highly conductive LIG from paper and related materials, paving the way for its application, with reduced cost and low environmental impact, in fields ranging from biomonitoring to consumer electronics. [Display omitted] • Synthesis of laser-induced graphene from filter paper by a single irradiation step • Synthesis of laser-induced graphene by irradiation of filter paper containing activated charcoal • Laser-induced graphene from a xylan substrate, valorizing this underutilized natural product • Temperature sensor employing laser-induced graphene obtained from modified xylan [ABSTRACT FROM AUTHOR]