PET Functional Upcycling through Surface-Assisted Growth of Ni-BDC MOFs and Laser-Induced Carbonization towards Bend Resistive Sensor

The growing accumulation of waste polyethylene terephthalate (PET) presents a significant environmental challenge requiring the development of sustainable recycling methods. In this study, we propose a novel approach for upcycling PET waste into bend resistive sensors through laser-assisted carbonization of surface-grown Ni-BDC (BDC = 1,4-benzenedicarboxylate). The fabrication process involves the solvothermal formation of a homogeneous Ni-BDC layer, followed by treatment with a 405 nm laser system to create a graphene-like layer with enhanced conductivity (sheet resistance 6.2 ± 3.4 Ω per square). The developed sensor demonstrates remarkable robustness, a linear response in a wide bending angle range (6 to 44º), as well as excellent mechanical stability and stiffness. This contribution paves the way for the development of cost-effective and eco-friendly devices based on low-cost polymer waste as a resource for applications in the Internet of Things

Photochemistry dominates over photothermal effects in the laser-induced reduction of graphene oxide by visible light

Abstract Graphene oxide (GO) possesses specific properties that are revolutionizing materials science, with applications extending from flexible electronics to advanced nanotechnology. A key method for harnessing GO’s potential is its laser-induced reduction, yet the exact mechanisms — photothermal versus photochemical effects — remain unclear. Herein, we discover the dominant role of photochemical reactions in the laser reduction of GO under visible light, challenging the prevailing assumption that photothermal effects are dominant. Employing a combination of Raman thermometry, X-ray photoelectron and photoluminescence spectroscopies, and electrical atomic force microscopy, we quantify the temperature and map the reduction process across micro and nano scales. Our findings demonstrate that the photochemical cleavage of oxygen-containing groups below a reduction threshold temperature is a decisive factor in GO reduction, leading to distinct characteristics that cannot be replicated by heating alone. This work clarifies the fundamental mechanisms of GO transformation under visible laser irradiation, highlighting the dominant role of photochemical processes. Distinguishing these subtleties enables the development of laser-reduced GO platforms for graphene-based applications compatible with industrial scales. We illustrate this potential by encoding information on GO surfaces as optical storage, allowing us to write binary sequences in long-term memory encoding invisible even through an optical microscope

Universal Approach to Integrating Reduced Graphene Oxide into Polymer Electronics

Flexible electronics have sparked significant interest in the development of electrically conductive polymer-based composite materials. While efforts are being made to fabricate these composites through laser integration techniques, a versatile methodology applicable to a broad range of thermoplastic polymers remains elusive. Moreover, the underlying mechanisms driving the formation of such composites are not thoroughly understood. Addressing this knowledge gap, our research focuses on the core processes determining the integration of reduced graphene oxide (rGO) with polymers to engineer coatings that are not only flexible and robust but also exhibit electrical conductivity. Notably, we have identified a particular range of laser power densities (between 0.8 and 1.83 kW/cm2), which enables obtaining graphene polymer composite coatings for a large set of thermoplastic polymers. These laser parameters are primarily defined by the thermal properties of the polymers as confirmed by thermal analysis as well as numerical simulations. Scanning electron microscopy with elemental analysis and X-ray photoelectron spectroscopy showed that conductivity can be achieved by two mechanisms—rGO integration and polymer carbonization. Additionally, high-speed videos allowed us to capture the graphene oxide (GO) modification and melt pool formation during laser processing. The cross-sectional analysis of the laser-processed samples showed that the convective flows are present in the polymer substrate explaining the observed behavior. Moreover, the practical application of our research is exemplified through the successful assembly of a conductive wristband for wearable devices. Our study not only fills a critical knowledge gap but also offers a tangible illustration of the potential impact of laser-induced rGO-polymer integration in materials science and engineering applications

Electrochemical Switching of Laser-Induced Graphene/Polymer Composites for Tunable Electronics

Laser reduction of graphene oxide (GO) is a promising approach for achieving flexible, robust, and electrically conductive graphene/polymer composites. Resulting composite materials show significant technological potential for energy storage, sensing, and bioelectronics. However, in the case of insulating polymers, the properties of electrodes show severely limited performance. To overcome these challenges, we report on a post-processing redox treatment that allows the tuning of the electrochemical properties of laser-induced rGO/polymer composite electrodes. We show that the polymer substrate plays a crucial role in the electrochemical modulation of the composites’ properties, such as the electrode impedance, charge transfer resistance, and areal capacitance. The mechanism behind the reversible control of electrochemical properties of the rGO/polymer composites is the cleavage of polymer chains in the vicinity of rGO flakes during redox cycling, which exposes rGO active sites to interact with the electrolyte. Sequential redox cycling improves composite performance, allowing the development of devices such as electrolyte-gated transistors, which are widely used in chemical sensing applications. Our strategy enables the engineering of the electrochemical properties of rGO/polymer composites by post-treatment with dynamic switching, opening up new possibilities for flexible electronics and electrochemical applications having tunable properties

Surface-Enhanced Raman Spectroscopy and Electrochemistry: The Ultimate Chemical Sensing and Manipulation Combination

One of the lessons we learned from the COVID-19 pandemic is that the need for ultrasensitive detection systems is now more critical than ever. While sensors’ sensitivity, portability, selectivity, and low cost are crucial, new ways to couple synergistic methods enable the highest performance levels. This review article critically discusses the synergetic combinations of optical and electrochemical methods. We also discuss three key application fields—energy, biomedicine, and environment. Finally, we selected the most promising approaches and examples, the open challenges in sensing, and ways to overcome them. We expect this work to set a clear reference for developing and understanding strategies, pros and cons of different combinations of electrochemical and optical sensors integrated into a single device

Textile Electronics with Laser-Induced Graphene/Polymer Hybrid Fibers

The concept of wearables is rapidly evolving from flexible polymer-based devices to textile electronics. The reason for this shift is the ability of textiles to ensure close contact with the skin, resulting in comfortable, lightweight, and compact “always with you” sensors. We are contributing to this polymer-textile transition by introducing a novel and simple way of laser intermixing of graphene with synthetic fabrics to create wearable sensing platforms. Our hybrid materials exhibit high electrical conductivity (87.6 ± 36.2 Ω/sq) due to the laser reduction of graphene oxide and simultaneous laser-induced graphene formation on the surface of textiles. Furthermore, the composite created between graphene and nylon ensures the durability of our materials against sonication and washing with detergents. Both of these factors are essential for real-life applications, but what is especially useful is that our free-form composites could be used as-fabricated without encapsulation, which is typically required for conventional laser-scribed materials. We demonstrate the exceptional versatility of our new hybrid textiles by successfully recording muscle activity, heartbeat, and voice. We also show a gesture sensor and an electrothermal heater embedded within a single commercial glove. Additionally, the use of these textiles could be extended to personal protection equipment and smart clothes. We achieve this by implementing self-sterilization with light and laser-induced functionalization with silver nanoparticles, which results in multifunctional antibacterial textiles. Moreover, incorporating silver into such fabrics enables their use as surface-enhanced Raman spectroscopy sensors, allowing for the direct analysis of drugs and sweat components on the clothing itself. Our research offers valuable insights into simple and scalable processes of textile-based electronics, opening up new possibilities for paradigms like the Internet of Medical Things