This study investigates the effect of laser power, focal length, and number of passes on the fabrication of graphene-based strain sensors using a 450 nm diode laser at the upper limit of the UV spectrum. Polyimide substrates were irradiated to produce laser-induced graphene, and the resulting sensors were evaluated under three-point bending tests. The main requirements for deformation sensors—adequate conductivity, mechanical stability under bending, and high sensitivity (gauge factor)—were assessed through morphological analysis by SEM, Raman spectroscopy, and electrical characterization using the Van der Pauw method. The results indicate that laser power is the critical factor influencing graphene quality and sensor performance, while focal length has a negligible effect and additional passes reduce material quality and sensitivity. Overall, this work demonstrates the feasibility of producing functional, low-cost graphene strain sensors with a commercial diode laser, offering a scalable and affordable alternative for sensor fabrication.

The development of biofuels aligned with the circular economy has gained increasing attention as a sustainable alternative to non-renewable energy sources. This study aims to evaluate the physical and thermal properties of biomass briquettes derived from potato stalk residues to assess their potential as biofuels. For this, dried potato stalk residues were subjected to pyrolysis for carbonization, followed by grinding and mixing with potato and achira binders in proportions of 10% and 20%, respectively. The briquetting process was performed at a pressure of 10 MPa with compaction times of 30 and 60 s. Scanning electron microscopy (SEM) revealed a porous structure with uniform binder distribution, while Raman spectroscopy confirmed the presence of D and G bands, indicative of amorphous carbon structures with graphite-like imperfections. Thermogravimetric analysis (TGA) determined a moisture content of 10%, which ensures stability. Non-carbonized briquettes exhibited higher compressive strength, withstanding forces in excess of 400 N at 20% deformation. The average calorific value of both briquette types was 15 MJ/kg, comparable to biofuels derived from sugarcane bagasse and rice hulls, with samples exceeding the 12 MJ/kg threshold for biomass fuel classification. These results indicate that potato stalk briquettes could be a viable biofuel alternative to support renewable energy diversification.

The design and development of a temperature and pressure transmitter using a laser-induced graphene (LIG) sensor represents a significant advance in precision measurement technology. LIG, characterized by its unique porous structure and tailored flaw engineering, exhibits exceptional electrical and thermal conductivity, high mechanical strength, and flexibility, making it ideal for highly sensitive sensing applications. In this study, a sensor was directly patterned with LIG on a flexible substrate to enable real-time monitoring of temperature and pressure changes. Temperature is measured through LIG's intrinsic resistance variation, while pressure is sensed via its enhanced piezoresistive properties arising from its engineered porosity and defect structure. A signal conditioning and processing circuit was implemented for calibration and data visualization, featuring a modular design that supports long-distance data transmission via a standard 4–20 mA current loop. Moreover, the LIG fabrication process is inherently simple, cost-effective, and environmentally friendly. The single-step laser-induced patterning method eliminates the need for high temperatures, chemical solvents, and complex processing, thereby reducing energy consumption, production costs, and environmental impact. This approach positions LIG-based sensors as a promising low-cost and sustainable alternative to traditional sensor technologies. Experimental results demonstrate high accuracy, fast response times, and low power consumption, underscoring the potential of LIG technology in next-generation industrial and biomedical sensing applications.

Assistive mobility devices for small animals require reliable monitoring to ensure safe and comfortable operation without increasing system complexity or invasiveness. This study presents a low-cost monitoring platform that integrates a laser-induced graphene (LIG) contact-temperature sensor into a passive mobility device for small dogs, supported by a lightweight Internet of Things (IoT) architecture. The system combines contact temperature, ambient temperature, speed, and obstacle distance using an energy-aware acquisition strategy and prioritized wireless transmission for near-real-time monitoring. An unsupervised anomaly detection framework based on Isolation Forest identifies potentially unsafe operating conditions without labeled pathological data by leveraging absolute temperature and the differential feature $\Delta T$ between contact and ambient measurements. Experimental validation was conducted under controlled indoor conditions across six independent sessions with a small-breed dog, including static and dynamic phases to ensure repeatability. The system achieved packet delivery ratios of approximately 95%, with typical end-to-end latencies below 500 ms and worst-case delays below 850 ms. The proposed approach detected localized thermal deviations associated with friction or prolonged contact while remaining robust to normal activity- and environment-driven variations. These results demonstrate the feasibility of integrating LIG-based sensing and unsupervised analytics into assistive animal mobility platforms to enhance safety through continuous, non-invasive monitoring.

Microclimatic stress strongly influences the ecological resilience of Vasconcellea stipulata (Toronche), yet current monitoring approaches rely on sparse measurements and lack real-time predictive capability. This work introduces an AI-enhanced virtual sensing framework based on laser-induced graphene (LIG) designed to emulate the thermoresistive response of an LIG transducer and generate high-resolution environmental indicators for microclimatic analysis. Unlike conventional LIG sensors or standalone IoT systems, the proposed framework integrates experimental calibration, data-driven modeling, and embedded inference into a unified architecture suitable for lightweight deployment on edge devices. A multilayer perceptron (MLP) model trained on laboratory data reproduced the temperature- and humidity-dependent electrical behavior of the transducer with high fidelity, achieving an RMSE of 0.016 k$\Omega$ in the calibrated range (10–60 °C) and remaining below 0.09 k$\Omega$ under noisy and extrapolated conditions. Sensitivity analysis identified temperature as the dominant driver (71%), followed by solar irradiance (19%) and relative humidity (10%), consistent with the microstructural mechanisms governing LIG’s response. The virtual sensor enables continuous, low-cost environmental monitoring and provides quantitative variables that can support downstream ecological interpretation. Overall, the results highlight the potential of AI-enhanced LIG–IoT architectures for advancing real-time microclimatic assessment in resource-limited Andean ecosystems.

This paper introduces the design and fabrication of a versatile capacitor bank developed specifically for its integration within the innovative flash joule heating (FJH) technique, aimed at synthesizing graphene. The capacitor bank offers two adaptable configurations, providing options for capacitance at 180,000 µF and 68,000 µF, combined with a maximum charging capability of 400 V. This equipment facilitates the swift conversion of carbon-containing materials into graphene by harnessing transient current discharges. The proposed capacitor bank facilitates the execution of comprehensive research pertaining to graphene production from diverse carbon sources, opening an opportunity for advancing exploration within this rapidly evolving field of study in Ecuador.