The discovery of laser-induced graphene (LIG) from polyimide films via laser pyrolysis ignited extensive research into using lasers for pyrolyzing flexible polymer films to create carbon-based materials. Despite this progress, the synthesis of graphite through laser pyrolysis has not yet been documented, nor has the laser pyrolysis of polyethylene naphthalate (PEN) films, which are commonly used as flexible substrates. In this study, we report the laser pyrolysis of PEN films, which produces disordered graphite with an expanded interlayer spacing of 0.37 nm, termed laser-induced graphite (LIGT) to differentiate it from LIG. The optimized LIGT exhibits a sheet resistance as low as 24 Omega/sq, and its utility as a flexible Joule heater is demonstrated, reaching a maximum temperature of approximately 154 degrees C. These results establish PEN as a viable precursor for laser-synthesized graphite and highlight the potential of LIGT for flexible electronic applications.

Tungsten trioxide (WO3) is a promising electrochromic material owing to its reversible structural and optical modulation under applied voltage. Despite advantages such as rapid switching and electrochemical stability, the functional diversification of electrochromic devices (ECDs) remains limited, largely due to the absence of effective patterning strategies. Here, we present a facile laser ablation approach for precise and controllable patterning of WO3 thin films, enabling on-demand optical transmittance modulation. The laser-defined patterns can further serve as simple informative display elements, demonstrating localized visual switching based on patterned geometries. The process removes both the WO3 layer and the underlying fluorine-doped tin oxide (FTO) layer from the glass substrate, as confirmed by UV-vis spectrometry and X-ray diffraction. The influence of patterning density on thermal management performance is further evaluated under infrared irradiation, revealing its potential for heat-shielding functionality in optoelectronic applications.

We fabricated flexible resistive and photocurrent switching devices based on VO2 films grown on a 3-mu m-thick mica substrate using a laser ablation patterning process, enabled by the unique thermal and electrical insulating properties of mica. We confirmed that the metal-insulator transition characteristics of the VO2 film grown on the mica substrate remained stable under outward and inward bending deformations, with curvature kappa ranging from +0.2 mm(-)(1) to -0.2 mm(-)(1). The flexible VO2 devices demonstrated stable and fast resistive switching performances even at low voltages. Additionally, the devices generated a photocurrent proportional to the light intensity at low bias voltages. Notably, we demonstrated that the photocurrent switching behavior of the flexible VO2 device can be adjusted using pulsed-voltage measurements. These results suggest that the flexible VO2/mica device, fabricated via a laser ablation patterning process, provides a cost-effective and straightforward approach for developing flexible VO2-based resistive memory and optoelectronic devices.

Protecting electronic circuits is essential for devices that directly interface with harsh external environments, as exposure to chemical contaminants and physical stimuli can lead to adverse effects, including corrosion, degradation, and disconnection. To address this challenge, we present an embedded monolithic vertical interconnect access (VIA) structure composed of conductive laser-induced graphene (LIG), fabricated through successive laser pyrolysis of a colorless polyimide (CPI) film in an out-of-plane orientation. This approach enables seamless integration between external functional units and internal conductive pathways, effectively isolating circuits from hazardous environments to ensure more robust and reliable operation. To evaluate its effectiveness, we tested two LIG network configurations-with and without the LIG-VIA (LIG-V)-under corrosive chemical conditions using 35 % H2O2 solution. The results confirmed that the LIG-V structure imparts chemoresistive properties while retaining conductivity after 1000 cycles at 0.79 % bending strain under repetitive bending. Furthermore, we demonstrated that the final structure functions as either a standalone bidirectional input/output device or as an auxiliary component to enhance other functional elements, such as a thermochromic display. By integrating the LIG-V structure into a transparent CPI substrate, this work presents promising potential for applications in wearable monitoring devices and on-demand feedback stimulation systems, unlocking new possibilities for functional electronics in dynamic and demanding environments.

In this work, a facile fabrication of ZnO-Ag hybrid gas sensors on laser-patterned FTO electrodes is demonstrated. Interdigitated electrodes are defined by nanosecond laser ablation, eliminating photolithography. ZnO films are spin-coated, and Ag nanoparticles are photoreduced under UV irradiation, where extended exposure transforms particles into plate-like structures with increased surface area. The ZnO–Ag(240) sensor shows good H2S sensing performance at 200℃, with rapid response/recovery (TRes: 10.7 s/TRec: 193.5 s), high linearity (R2 = 0.992), and strong selectivity toward H₂S over other gases.

Zinc oxide (ZnO) is a highly promising material for ultraviolet (UV) photodetection, owing to its wide bandgap (∼3.34 eV), high exciton binding energy, and cost-effective synthesis. Its piezoelectric properties further enhance its utility in wearable electronics. However, the inherent brittleness of ZnO nanowires (NWs) poses challenges in achieving reliable performance under strain. In this study, a novel flexible piezo-responsive photodetector with enhanced electrical performance is synthesized by hierarchical growth of ZnO NW branches on a silver nanowire (Ag NW) backbone, coupled with a UV laser ablation process for precise patterning. Further, the flexibility and stability are enhanced by the addition of a polydimethylsiloxane (PDMS) layer, thereby enabling consistent operation under stretching of up to 40%. The device integrates UV photodetection and piezoelectric strain sensing into a single platform, thereby addressing the demands for wearable sensors and piezoelectric nanogenerators. This multi-functional sensor demonstrates applications in motion monitoring, real-time UV exposure assessment, and self-powered wearable electronics, and establishes a robust framework for flexible optoelectronic sensors.

Due to more advantageous than rigid electronics in terms of productivity and another possibility for new research field, flexible photo-electrochemical (PEC) water-splitting cells have huge potential. However, photo-electrochemically instability of curre nt collector under harsh aqueous electrolyte condition and hightemperature post-annealing of transition metal-oxide based photoanodes are limited in making a flexible PEC water-splitting cells. Here, we report a novel approach to make a flexible thin-film PEC water-splitting cell by using femtosecond laser processing techniques. Using direct laser writing carbonization and femtosecond laser crystalline phase transformation, the fabricated flexible thin-film phot oanode demonstrated strong PEC performance. Moreover, it exhibited outstanding mechanical durability, even under extreme bending conditions. Thanks to its robust mechanical properties, the flexible thin-film photoanode enables space-efficient hydrogen ha rvesting by forming a volume-reduction structure.

Laser-induced graphene (LIG) has driven significant advances in wearable electronics, advanced healthcare, and energy devices. However, achieving diverse functionalities and high-performance for practical use requires integrating functional materials, which remains challenging due to poor synthesis results or complex chemical treatments. Herein, direct, seedless growth of transition-metal-oxide (MO) crystalline nanorods on LIG is demonstrated, even under lattice-mismatch conditions, via a non-epitaxial process. Ultrafast laser pyrolysis during LIG formation introduces nitrogen- and oxygen-containing surface groups that facilitate the nucleation of MO during subsequent synthesis, enabling the selective growth of MO nanorods exclusively on LIG patterns without additional lattice-matching or patterning steps. Through this non-epitaxial growth, crystalline orthorhombic WO3·0.33 H2O and β-FeOOH nanorods are successfully synthesized on LIG micro-patterns. As a proof-of-concept, LIG electrodes integrated with these crystalline MO nanorods are employed in all-solid-state micro-supercapacitors, exhibiting significantly enhanced capacitive performance owing to the electrochemical reactivity of the MO nanorods, together with excellent mechanical and cyclic stability. Beyond this demonstration, the non-epitaxial strategy offers a versatile route for harnessing the diverse functionalities of MO nanostructures, unlocking new possibilities in graphene-based electronics.

Triboelectric nanogenerators (TENGs) harvest electrical energy from interfacial separation, yet achieving programmable and enhanced output through controlled separation mechanisms remains challenging. Here, a metamaterial adhesive‐integrated TENG (MetaAdh‐TENG) is presented that employs nonlinear cut architectures within an adhesive film embedded with silver nanowire (AgNW) electrodes. This structure enables spatially programmable and enhanced triboelectric charge generation and adhesion. Compared to planar counterparts, the MetaAdh‐TENG exhibits a 12.8 fold increase in peak voltage (7.3 V) and a 34.8 fold enhancement in peel adhesion (202.3 N m⁻¹) by accelerating local crack velocity through crack trapping and reverse crack propagation. By tailoring the cut geometry, the charge output, adhesion strength, and their directionality can be independently and locally controlled, enabling tunable performance across a single device. These features support multifunctional applications, such as battery‐free smart adhesives for fall detection and door‐opening alarms, as well as roll‐type systems for continuous charge generation.

In recent years, smart materials, also known as stimuli-responsive materials, have driven advancements in deformable electronic devices, enabling active shape transformations beyond the passive deformations of traditional flexible electrodes. However, existing reconfigurable electrodes based on smart materials often rely on thermal stimuli, which limit their applications in environments where precise temperature control is challenging. Additionally, these systems are typically restricted to two-dimensional film configurations, confining their deformation modes to simple in-plane bending or twisting. To overcome these limitations, here we describe a novel reconfigurable electronic system, referred to as LIG-on-PI/A-cLCE (LPAL), by integrating bilayers of electrode and substrate. The electrode layer is prepared by formation of laser-induced graphene (LIG) on a commercial polyimide film and the substrate layer is prepared by azobenzene-functionalized semi-crystalline liquid crystal elastomer (A-cLCE). LIG provides electrical conductivity to the system, while A-cLCE enables on-demand shape reconfiguration through photoisomerization under UV or visible light stimuli. LPAL eliminates reliance on thermal stimuli, allowing non-contact actuation including underwater environments, while maintaining stable electrical conductivity during repeated deformations. Furthermore, leveraging the crystallinity-assisted restructuring of A-cLCE, we fabricated a three-dimensional spiral-LPAL, achieving exceptional stretchability (similar to 200 % strain) and retaining 100 % original conductivity after 1000 cycles of tensile deformation. This spiral design introduces reversible lengthwise contraction and elongation under light stimuli, expanding deformation capabilities beyond conventional in-plane modes. Finally, we demonstrate the versatility of spiral-LPAL by implementing an untethered electrical switch functions in both ambient and underwater environments, showcasing its potential for advanced reconfigurable systems.

Despite its potential for clean hydrogen harvesting, photoelectrochemical (PEC) water-splitting cells face challenges in commercialization, particularly related its harvesting performance and productivity at an industrial scale. Herein, a facile fabrication method of flexible thin-film photoanode for PEC water-splitting to overcome these limitations, based on laser processing technologies, is proposed. Laser-induced graphene, a carbon structure produced through direct laser writing carbonization (DLWC), plays a dual role: a flexible and stable current collector and a substrate for the hydrothermal synthesis of tungsten trioxide (WO3) nanorods (NRs). To facilitate water-splitting, a femtosecond-pulsed laser (fs laser) is focused on the WO3 NRs, converting their crystalline phase from pristine orthorhombic to monoclinic structure without thermal damage. With NiFe layered double hydroxide (LDH) catalyst, the flexible thin-film photoanode exhibits good PEC performance (1.46 mA cm(-2) at 1.23 V-RHE) and retains approximate to 90% of its performance after 3000 bending cycles. With its excellent mechanical properties, the flexible photoanode can be operated in various shapes with different curvatures, enabling space-efficient PEC water-splitting by loading larger photoanode within a given space. This study is expected to contribute to the advancement of large-scale solar water-splitting cells, introducing a new approach to enhance H-2/O-2 production and expand its application range.

This review examines recent manufacturing technologies of solar water-splitting cells. It covered vacuum-based manufacturing, highlighting recent advances in laser-based processes and discussing their innovative potential and future perspectives.

Stretchable and self-adhesive conductive hydrogels hold significant importance across a wide spectrum of applications, including human–machine interfaces, wearable devices, and soft robotics. However, integrating multiple properties, such as high stretchability, strong interfacial adhesion, self-healing capability, and sensitivity, into a single material poses significant technical challenges. Herein, we present a multifunctional conductive hydrogel based on poly(acrylic acid) (PAA), dopamine-functionalized pectin (PT-DA), polydopamine-coated reduction graphene oxide (rGO-PDA), and Fe 3+ as an ionic cross-linker. This hydrogel exhibits a combination of high stretchability (2000%), rapid self-healing (~ 94% recovery in 5 s), and robust self-adhesion to various substrates. Notably, the hydrogel demonstrates a remarkable skin adhesion strength of 85 kPa, surpassing previous skin adhesive hydrogels. Furthermore, incorporating rGO within the hydrogel network creates electric pathways, ensuring excellent conductivity (0.56 S m –1 ). Consequently, these conductive hydrogels exhibit strain-sensing properties with a significant increase in gauge factor (GF) of 14.6, covering an extensive detection range of ~ 1000%, fast response (198 ms) and exceptional cycle stability. These multifunctional hydrogels can be seamlessly integrated into motion detection sensors capable of distinguishing between various strong or subtle movements of the human body.

Diabetes, a chronic metabolic disease affecting millions of people worldwide, necessitates the development of low-cost and reliable nonenzymatic glucose sensors for effective diabetes management on a global scale. This paper presents an approach using laser processing to fabricate nonenzymatic glucose sensors based on nanoporous Cu thin films (CuTFs). By subjecting a CuO nanorod array to a laser-induced photoreduction (LIPR) process, a highly efficient and sensitive glucose sensor is achieved through the transformation into a nanoporous CuTF. The nanoporous CuTF-based glucose sensor exhibits exceptional sensitivity, with a response of approximately 2.2 mA mM(-1) cm(-2), and an impressively low detection limit of 0.025 mu M. Furthermore, the sensor demonstrates remarkable stability, retaining 96% of its initial current response throughout a comprehensive 15-day evaluation. Additionally, the sensor exhibits excellent selectivity, effectively distinguishing glucose from interfering substances, such as ascorbic acid or uric acid, thereby establishing its reliability for glucose-sensing applications. Furthermore, the CuTF-based glucose sensor is applied to a human sweat-based noninvasive glucose sensor. The utilization of the LIPR process for fabricating the nanoporous CuTF holds great potential in advancing the field of advanced glucose-sensing technologies.

In this study, we integrate medium-entropy cocatalysts (MECs), composed of four elements-Fe, Ni, Co, and Cr-into nanostructured hematite (Fe2O3) thin films using a laser deposition process to enhance the photoelectrochemical (PEC) water splitting performance. The MEC-integrated hematite (MEC-Fe2O3) photoanodes exhibit remarkable improvements in water oxidation photocurrent, achieved through enhanced charge injection efficiency and a negatively shifted onset potential compared to bare Fe2O3. Multiphysics modeling elucidates the laser-induced MEC formation mechanism by estimating the temperature increase and changes in energy band structure and carrier concentrations. Furthermore, time-resolved photoluminescence (TRPL) studies unveil that the MEC layer extends the carrier lifetime of photogenerated charge carriers, leading to an overall enhancement in the efficiency of the water oxidation process. This work highlights the promising potential of laser-deposited MEC as a viable strategy to boost the efficiency of hematite photoanodes in PEC water splitting applications.

Polydimethylsiloxane (PDMS) is a widely used elastomer substrate in various fields, including wearable devices, because of its diverse advantages. However, PDMS has low stretchability and lack of adhesion, thus requires additive adhesives, such as conventional tapes, which have potential to cause skin trauma. Meanwhile, polyurethane acrylate (PUA) is also a broadly used elastomer given its various advantages, such as biocompatibility and mechanical properties. This study introduces, for the first time, a novel laser process method to form an adhesive-free PDMS/PUA bilayer film. By adjusting UV laser scanning parameters, the interfacial bonding between the PDMS and PUA can be improved without additional additives. The fabricated PDMS/PUA bilayer showed high transparency, improved mechanical properties, and adhesiveness properties. Combining with PUA (as a backbone and adhesive layer) and PDMS (as a triboelectric layer), the PDMS/PUA bilayer was further used to fabricate a transparent, attachable, and stretchable PDMS/PUA-based triboelectric nanogenerator (PP-TENG) device. The transparent attachable PP-TENG successfully detected minute human motions and functioned as a virtual piano keyboard and a virtual computer keyboard when attached to an arbitrary paper.

UV micro-photodetectors (mPDs) have received significant attention owing to the increasing demand for application in wearable healthcare devices. However, mPDs often suffer from tiny signals owing to their small size. Although this problem can be overcome by using low-dimensional nanomaterials with high surface-to-volume ratios, such as nanowires (NWs), selective synthesis of functional NWs on the desired position of the specific substrate is challenging. This study introduces, for the first time, the laser-induced hydrothermal growth (LIHG) process, in which a strongly focused laser beam generates a localized high-temperature field, enabling the localized growth of CuO NWs on the desired position of the specific substrate. Also, an all-laser direct patterning process for the fabrication of a flexible mPD based on a p-CuO NW/n-ZnO NW heterojunction is demonstrated. The PN NWs heterojunction exhibits remarkable photocurrent enhancement compared to a homojunction with a single semiconductor material. Furthermore, the all-laser direct patterning process of the flexible PN NWs heterojunction can be applied for the fabrication of other flexible optoelectronic applications.

Simply oxygen evolution Ni, Co-doped FeOOH cocatalyst layers were deposited by laser-induced deposition on WO 3 photoanodes for enhanced PEC performance.

Polyurethane (PU) is the most extensively used soft backbone substrate for wearable applications. However, even with biocompatibility and stretchability, PU-based wearable devices are unsuitable for epidermal devices because they lack of adhesive properties. To impart adhesive properties to PU, commercial adhesive additives are required or the mixing ratio of specific materials should be adjusted. Despite PU biocompatibility, additional additives cause skin damage because they are not usually biocompatible due to their toxic ingredient. This study introduces a simple method of fabricating self-adhesive polyurethane (SAPU) without specific adhesive additives for a biocompatible epidermal soft sensor and an attachable epidermal thermal heater. During the selective photo-polymerization of PU resin, the defective crosslinking networks between laser-scanned resin lines enhance the adhesive properties of PU. Adjusting photopolymerization conditions results in self-adhesive polyurethane with high adhesiveness and low Young's modulus comparable to those of human skin. A mouse skin toxicity test confirms the biocompatibility and highly conformal contact of SAPU. SAPU is then further applied for the fabrication of a biocompatible epidermal soft sensor and an attachable epidermal thermal heater with silver nanowire network. The fabricated self-adhesive epidermal soft sensor successfully detects human motion and bio-signals, whereas the self-adhesive epidermal soft heater efficiently transfers heat to the epidermis due to its excellent conformal contact characteristics on the human skin. (c) 2022ElsevierLtd. Allrightsreserved.