This paper presents a comprehensive study on the synthesis, characterization, and integration of laser-synthetized graphene-based materials in a wearable device for non-invasive physiological monitoring. Laser-induced graphene (LIG) and Laser-reduced graphene oxide (LrGO) materials are synthetized and characterized under different techniques to analyze and compare their structural and chemical properties, including scanning electron microscopy (SEM), micro-Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). These materials are used afterwards for the fabrication of temperature sensors, micro-supercapacitors (MSCs), and electrocardiogram (ECG) electrodes. In particular, the temperature dependence of the electrical conductivity of LrGO is exploited for the fabrication of temperature-dependent resistors with a sensitivity of -1.23 kΩ · °C ^-1 , which are used as body temperature sensors after being encapsulated into polydimethylsiloxane (PDMS) to increase their linearity and immunity to humidity changes. Moreover, both MSCs and ECG electrodes are developed by leveraging the highly porous structure of LIG, demonstrating a good electrochemical and ECG acquisition performance. Furthermore, a wearable device is designed and fabricated integrating these graphene-based components in a rigid-flex printed circuit board (PCB) together with a Bluetooth Low Energy (BLE) microcontroller, thus enabling the wireless transmission of the physiological data to external monitoring devices. The power consumption has been optimized for extended battery life, allowing continuous monitoring over prolonged periods. Overall, this study demonstrates the feasibility and effectiveness of integrating graphene-based materials into real wearable applications.

This work presents the optimization of the fabrication procedure for laser-induced graphene (LIG) electrodes intended for biopotentials acquisition. The results presented in this study demonstrate a significant improvement with respect to the performance obtained for other LIG-based electrodes previously reported in the literature. In particular, we propose the use of a galvanometric laser instead of a CNC laser to improve the engraving resolution and the LIG synthesis process, thus enhancing the surface area of the interface skin–electrode. For that, we have studied the resistance of the resulting LIG patterns as a function of the laser parameters (engraving power and scan speed) seeking their optimization. After tunning the laser fabrication process, we have fabricated and characterized electrocardiogram (ECG) electrodes with different surface areas using a commercial silver-based electrode as a reference. Thus, circular electrodes with a diameter of 15 mm, 10 mm and 6.5 mm were used to acquire the ECG on different volunteers using a commercial equipment. The signals acquired were processed afterwards with cutting edge processing techniques to perform a statistical analysis in terms of sensitivity, specificity, positive prediction and accuracy for the detection of QRS complexes. The results demonstrate that the proposed electrodes improve the signal acquisition with respect to the previously reported LIG-based electrodes in terms of noise and do present comparable or even better results than commercial electrodes (even with a smaller surface area) with the additional advantage of not requiring the use of an electrolyte gel.

Emerging sensing materials are central to improving the functionality and integration of electronic devices. In this study, we report the synthesis of a custom perylene-based organic ligand, N,N′-di­(phenyl-3,5-dicarboxylic acid)-perylene-3,4:9,10-tetracarboxylic acid diimide (PY), which exhibits a strong response to relative humidity (RH). Its sensing performance was systematically compared with that of a commercially available perylene derivative, N,N′-bis­(4-methoxy-benzyl)­perylene-3,4:9,10-bis­(dicarboximide) (PBI). Both materials were deposited onto polyimide substrates with silver-based dispense-printed interdigitated electrodes to fabricate impedimetric sensors. The PY-based sensor demonstrated a high sensitivity of −5289 Ω/% RH at 1 kHz within a 30–90% RH range while exhibiting minimal temperature dependence. In contrast, the PBI-based sensor showed a lower humidity sensitivity of −452 Ω/% RH and a negligible temperature response. This study highlights the potential of functionalized perylene derivatives for developing high performance humidity sensors with minimal thermal interference, eliminating the need for temperature compensation and enabling integration into low power electronic systems. These findings provide valuable insights into molecular design strategies for next-generation environmental monitoring and flexible electronic applications.

Two novel metal-organic frameworks (MOFs), based on dysprosium as the metal and the 5-aminoisophthalic acid (5aip) ligand, have been solvothermally synthesized, with the aim of studying and modulating their luminescence properties according to the variation of solvent in the structure. These materials display intense photo-luminescence properties in the solid state at room temperature. Interestingly, one fascinating sensory capacity of compound 2 regards obtaining a variation of the signal, depending on the solvent to which it is exposed. These results pave the way for a new generation of sensitive chemical sensors.

This work presents a novel approach to the fabrication of interdigitated electrodes (IDEs) using flexible polymer substrates. Two substrates, polyimide (PI) and polyetherimide (PEI), are compared alongside two manufacturing techniques: direct laser tracing and silver ink printing. The IDEs produced are applied to the detection of glucose and salt content in biological samples through impedance measurements. The analysis of impedance response enables the quantification of the relationship between signal magnitude and analyte concentration for both sensors and solutions, allowing for the estimation of unknown concentrations based on measured impedance values. The results obtained demonstrate the potential of the manufactured electrodes for non-invasive biosensing applications. This study highlights the sensitivity of these sensors for detecting glucose concentrations in the range of hypo- and hyperglycemia (0.7-1.8 mg/mL) and salt content, revealing their potential for use in real-time monitoring of important biological parameters. To further enhance analyte discrimination, an equivalent circuit model has been developed to describe the system’s electrical behavior, enabling effective differentiation between glucose and salt solutions. The findings suggest that the combination of flexible, low-cost substrates and impedance-based detection holds promise for advancing personalized health monitoring technologies, particularly for glucose and electrolyte balance.

On-skin non-invasive Wearable Health-Monitoring Devices (WHMDs) have rapidly evolved from laboratory prototypes into commercially viable systems capable of continuously tracking physiological and biochemical signals. By integrating epidermal temperature sensors, electrophysiological electrodes, biochemical sensing platforms, low-power electronics, and wireless communication technologies, these systems are emerging as key enablers of personalized and decentralized healthcare through the continuous acquisition of clinically relevant information directly from the skin surface. In this Perspective, we present our view on the state-of-the-art across the key technological pillars that define modern on-skin WHMDs, including non-invasive sensing strategies, advanced materials, processing and wireless communication units, energy-storage solutions, energy-harvesting techniques, and power-management architectures, with a particular focus on technologies that have already reached high Technology Readiness Levels (TRLs). We highlight how the next-generation of on-skin WHMDs must balance performance with sustainability and long-term reliability. This includes the adoption of biodegradable and recyclable materials, low-power and reconfigurable electronics, solid-state batteries, and hybrid energy-harvesting systems. By aligning technological innovation with human-centric and eco-friendly design principles, on-skin WHMDs can evolve into scalable, equitable, and environmentally responsible tools for future digital healthcare.