Flash healing of laser-induced graphene

In situ construction of multifunctional femtosecond laser-induced graphene on arbitrary substrates

The construction of laser-induced graphene (LIG) on various substrates is important for expanding new applications. However, current LIG transfer technologies are hampered by limited substrates, complicated processes, induced graphene defects, and single function. Herein, a facile laser processing method is proposed for in situ construction of multifunctional femtosecond laser-induced graphene (FsLIG) on arbitrary substrates utilizing femtosecond laser acting on polyimide tape. Unlike previous LIG transfer research, the proposed method is applicable to any substrates without introducing additional graphene defects, while also exhibiting multifunctionality. Raman spectra results confirm successful fabrication of FsLIG on various substrates involving paper, aluminum, ceramic, and silicon. Taking paper for example, FsLIG demonstrates multifunctional characteristics including high water contact angle (∼153.4°), large absorptance (∼98.8%), low sheet resistance (∼82.0 Ω sq-1), and reliable temperature sensing (∼-0.089% °C-1) properties. Our study provides a reliable pathway for fabricating multifunctional FsLIG on arbitrary substrates.

Coupling Amorphization and Compositional Optimization of Ternary Metal Phosphides toward High-Performance Electrocatalytic Hydrogen Production

Amorphous materials, with abundant active sites and unique electronic configurations, have the potential to outperform their crystalline counterparts in high-performance catalysis for clean energy. However, their synthesis and compositional optimization remain underexplored due to the strict conditions required for their formation. Here, we report the synthesis of ternary platinum-nickel-phosphorus (PtNiP) amorphous nanoparticles (ANPs) within milliseconds by flash Joule heating, which features ultrafast cooling that enables the vitrification of metal precursors. Through compositional optimization, the Gibbs free energy of hydrogen adsorption for Pt4Ni4P1 ANPs is optimized at 0.02 eV, an almost ideal value, even surpassing that of the benchmark metallic platinum catalyst. As a result, the PtNiP ANPs exhibited superior activity in electrocatalytic hydrogen evolution in acid electrolyte (η10 ∼ 14 mV, Tafel slope ∼ 18 mV dec-1, and mass activity 5× higher than state-of-the-art Pt/C). Life-cycle assessment and technoeconomic analysis suggest that, compared to existing processes, our approach enables notable reductions in greenhouse gas emission, energy consumption, and production cost for practical electrolyzer catalyst manufacturing.

Biomass-Based Sustainable Graphene for Advanced Electronic Technology: A Review

Through its remarkable mechanical, electrical, and thermal qualities, graphene has become a revolutionary material in electronics. Sustainable graphene synthesis from biomass residues offers a possible path toward adhering to the demand for economical and ecologically friendly graphene production methods. The present study thoroughly examines the numerous biomass sources used for graphene synthesis, such as plant-derived materials, agricultural waste, and other organic leftovers. The benefits and drawbacks of several synthesis methods are examined, including pyrolysis, chemical exfoliation, and hydrothermal carbonization. The study also explores the possible uses of graphene produced from biomass in electronics, including sensors, energy storage devices, electronic devices with flexibility, and electromagnetic interference (EMI) shielding. This review highlights how biomass-based graphene can revolutionize the electronics sector by bridging the gap between electronic applications, synthesis techniques, and biomass supplies.

Laser-Enabled Fabrication of Flexible Printed Electronics with Integrated Functional Devices

The demand for flexible and printed electronics in wearable and soft robotics applications has increased the need for scalable, additive manufacturing processes. However, traditional printed circuit board manufacturing involves complex, multistep processes, is limited to certain substrates, and faces challenges in integrating functional devices. Here, an additive, laser-enabled process is introduced for fabricating flexible, double-sided printed electronics leveraging laser-induced graphene (LIG) as a seed layer for selective copper electrodeposition (E-LIG). This technique enables precise conductive circuit patterning down to 50 µm and is reliable via formation in a single streamlined process. E-LIG supports transfer to various substrates, allowing for large-area electronics up to 100 cm2, broadening applications in large-scale interfaces. Functional LIG device integration, including sensors and actuators, directly interfaced with control circuits on a single substrate is demonstrated. Applications such as real-time graphical output and interactive interfacing showcase the method's versatility. E-LIG exhibits repairability for on-demand restoration of damaged circuits, enhancing durability and offering a scalable, cost-effective solution for multifunctional printed electronics.

Flexible Optoelectronic Hybrid Microfiber Long-period Grating Multimodal Sensor

Flexible wearable biosensors have emerged as a promising tool for tracking dynamic glycemic profiles of human body in diabetes management. However, it remains a challenge to balance the shrunken device space and multiple redundant sensing arrays for further advancement in miniaturization of multimodal sensors. Herein, this work proposes an entirely new optoelectronic hybrid multimodal optical fiber sensor which is composed of laser patterning of polydimethylsiloxane (PDMS) to form laser-induced graphene (LIG) as the interdigital electrodes, and a long period grating (LPG) prepared from an optical microfiber encapsulated into the PDMS modulated by periodical structure of LIG electrodes. This operation can simultaneously integrate two heterogeneous sensing mechanisms, optical and electrical, into a single sensor in a compact manner. Combining the LIG electrode with conductive hydrogel, a flexible glucose biosensor based on electrical mechanism is constructed by loading glucose oxidase into the hydrogel. Meanwhile, the microfiber LPG can also be served as a spectroscopically available sensor for biomechanical monitoring. Optical and electrical sensors can work simultaneously but independently of each other, particularly in the scene of wound healing for rat model and movement for human exercise. This platform represents a pivotal step toward multifunctional sensors that enable measurements of biomechanical information and glucose.

The Charge Storage Mechanism and Durable Operation in Olivine-Lithium-Iron-Phosphate for Mn-based Hybrid Batteries

Aqueous batteries have garnered considerable attention because of their cost-effectiveness, sufficient capacity, and non-flammable water-based electrolytes. Among these, manganese batteries are particularly attractive owing to their stability, abundance, affordability, and higher energy density. With a lower redox potential (Mn: -1.19 V vs SHE) than zinc (Zn: -0.76 V vs SHE), manganese batteries theoretically offer superior energy density over traditional zinc-based systems. In this study, LiFePO4 is introduced as a cathode material in aqueous manganese-based hybrid batteries for the first time. Through electrochemical characterization and advanced structural and spectroscopic analyses, the charge storage mechanisms of protons in to the FePO4 are elucidated. Cation diffusion pathways are also investigated via diffusion barrier calculations. This study presents manganese hybrid batteries with a good stability and capacity of ≈109.2 mAh g-1 at 40 mA g-1, alongside a cycle retention of 42.1% after 3000 cycles at 320 mA g-1. Furthermore, an Mn2+/Li+ hybrid battery, achieving ≈1.6 V and superior durability (81.5% @ 1000th), is proposed.

Reversible and Programmable Wettability of Laser-Induced Graphene Papers via In Situ Joule Heating-Triggered Superslippery Surfaces

Reversible surface materials with programmable wettability play an increasingly vital role in a wide variety of fields from science to industry. Based on laser-induced graphene (LIG) technology, we innovatively propose a paraffin-infused porous LIG paper (P-LIGP) with tunable superslippery wettability. On account of graphene's excellent electrical property, paraffin in P-LIGP can transit rapidly from a solid-to-liquid state in response to the in situ Joule heating effect. Thus, a LIGP surface is created with a dynamic and reversible transition between slippery and nonslippery state. In addition, combining the patternable performance with tunable LIGP resistance, the paraffin layer from P-LIGP can be selectively melted based on Ohm's law and Kirchhoff's laws, thus enabling special flow pathways with programmable wettability for manipulating the droplets with various straight/oblique/arc/S-shaped sliding patterns. These applications with customizable LIG resistance performance promise the in situ Joule heating of P-LIGP for designing intelligent and flexible temperature-responsive surfaces.

Stealth Materials Based on Laser-Induced Graphene: Developments and Challenges

Laser-induced graphene (LIG) has become a promising stealth material due to its excellent electromagnetic loss characteristics in the terahertz and microwave bands (2-18 Ghz) and the advantages of low-cost large-scale manufacturing. With the rapid advancement of electromagnetic detection technologies toward multispectral and high-dynamic-range capabilities, there is an increasing demand for LIG-based stealth materials with superior absorption performance. The synergistic design of functional material doping and structural configurations has been identified as a critical approach to achieve high electromagnetic shielding performance in LIG-based composites. This article briefly reviews the developmental progress of LIG-based electromagnetic stealth materials, with a particular emphasis on doping technologies and shielding mechanisms tailored for stealth applications. Furthermore, we propose potential future development pathways for LIG-based stealth materials to facilitate their transition toward broader practical applications.

Tailoring the Catalytic Activity of Metal Catalysts by Laser Irradiation

In recent years, the rapid advancements in laser technology have garnered considerable interest as an efficient method for synthesizing electrocatalytic nanomaterials. This review delves into the progress made in laser-induced nanomaterials for electrocatalysis, providing a comprehensive overview of the synthesis strategies and catalytic mechanisms involved in defect engineering, morphology tuning, and heterostructure formation. The review highlights the various laser-induced synthesis techniques in producing nanomaterials with enhanced electrocatalytic properties. It discusses the underlying mechanisms through which laser irradiation can induce defects, modify morphology, and create heterostructures in nanomaterials, ultimately leading to improved catalytic performance. The comprehensive summary of these synthesis strategies and catalytic mechanisms provides valuable insights for researchers interested in utilizing laser technology for the fabrication of advanced electrocatalytic materials. Furthermore, this review identifies the existing challenges and outlines future directions within this booming research field. By addressing the current limitations and discussing potential avenues for exploration, the review provides important guidance for researchers looking to design and fabricate laser-induced nanomaterials with desirable properties for advanced electrocatalysis and beyond.

Femtosecond Laser Opening Hierarchical Lamination: Micro-Nano Hybrid Scissoring of Three-Dimensional Nitrogen-Doped Graphene for Solar Steam Generation

Three-dimensional (3D) nanoporous nitrogen-doped graphene is an ideal candidate for solar steam generation. However, the outermost dense layer formed during high-temperature thermal chemical vapor deposition (CVD) severely blocks water transport and steam escape. In this work, a technique of femtosecond laser opening hierarchical lamination (FLOHL) enabling hierarchical micro-nano hybrid scissoring of graphene is presented for its structural and performance upgrades. FLOHL not only allows noncontact rapidly hierarchical opening of the blocked layer but also enables opening lamination of close thin-wall graphene into suspended sheets, while maintaining a robust connection with the framework facilitating stable repetitive use for water evaporation. After FLOHL, solar absorption, heat localization, and interfacial wetting are all dramatically enhanced, increasing water evaporation rates from 1.58/1.56 to 1.79/1.77 kg m-2 h-1 for two prototypes under 1 sun irradiation and conversion efficiency from ∼80% to ∼90%, making them better than many solar evaporators built with graphene and its derivatives, including laser-induced graphene.

Overcoming Interfacial Hydrogen Site-Blocking during Alkaline Formate Oxidation: Insights from Lattice-Compressed PdZr/C Catalysts

Improving the electrocatalytic conversion of formate in alkaline solutions is crucial for the commercial application of formate fuel cells. However, palladium-based catalysts used for formate oxidation reactions (FOR) face challenges due to the strong adsorption of hydrogen intermediates, resulting in lower catalytic efficiency in alkaline environments. Herein, we prepared a PdZr/C catalyst aimed at employing a doping-induced strain strategy to reduce the hydrogen binding energy of palladium and release more active sites for the oxidation of formate. Through density functional theory calculations and experimental investigations, we find that the lattice compression induced by Zr doping regulates the electronic structure of Pd. Specifically, the incorporation of Zr dopant shifts the d-band center of Pd downward, weakening the binding energy of hydrogen at the Pd sites. This adjustment promotes the desorption of hydrogen intermediates, thus accelerating the FOR kinetics by alleviating the site-blocking effect. As a result, the PdZr/C catalyst exhibited a 2.4-fold increase in activity compared to the conventional Pd/C catalyst. It also achieved a lower peak potential and delivered a significantly higher peak current of 1917 mA mg-1. These findings highlight the critical role of lattice strain in tuning the catalytic properties of Pd and offer valuable insights into the design of high-performance electrocatalysts for energy conversion technologies.

Hollow fiber-based strain sensors with desirable modulus and sensitivity at effective deformation for dexterous electroelastomer cylindrical actuator

The electroelastomer cylindrical actuators, a typical representation of soft actuators, have recently aroused increasing interest owing to their advantages in flexibility, deformability, and spatial utilization rate. Proprioception is crucial for controlling and monitoring the shape and position of these actuators. However, most existing flexible sensors have a modulus mismatch with the actuation unit, hindering the free movement of these actuators. Herein, a low-modulus strain sensor based on laser-induced cellular graphitic flakes (CGF) onto the surface of hollow TPU fibers (HTF) is present. Through the electrostatic self-assembly technology, the flexible sensor features a unique hybrid sensing unit including soft HTF as substrate and rigid CGF as conductive path. As a result, the sensor simultaneously possesses desirable modulus (~0.155 MPa), a gauge factor of 220.3 (25% < ε < 50%), fast response/recovery behaviors (31/62 ms), and a low detection limit (0.1% strain). Integrating the sensor onto the electroelastomer cylindrical actuators enables precise measurement of deformation modes, directions, and quantity. As proof-of-concept demonstrations, a prototype soft robot with high-precision perception is successfully designed, achieving real-time detection of its deformations during the crawling process. Thus, the proposed scheme sheds new light on the development of intelligent soft robots.

One-Step Laser-Guided Fabrication of 3D Self-Assembled Graphene Micro-Rolls

Laser-induced graphene (LIG) has been systematically investigated and employed because of the spartan laser synthesis and functional three dimensional (3D) foam-like structures. However, thermally induced deformation during laser processing is generally undesirable and, therefore, strictly suppressed. This work introduces a novel laser-guided self-assembly approach integrated into the fabrication of LIG to generate multiscale 3D graphene foam structures in a single step. Leveraging the photothermal effects of laser ablation on polyimide films, we achieve concurrent LIG production and self-assembly, enabling the transformation of two dimensional films into 3D micro-rolls. The process is finely tuned through interface modification and optimized laser parameters, allowing precise control over the geometry of the resulting structures. Systematic investigations reveal that varying laser power and line spacing effectively adjust the diameters of the LIG micro-rolls. Characterization indicates that the LIG micro-rolls can be fabricated with very large curvature and limited internal space, enhancing the potential for microscale applications. Furthermore, our laser strategy facilitates the creation of symmetric, asymmetric, and double-tube micro-rolls, underscoring its design flexibility. This work highlights the potential of the laser-guided self-assembly strategy in graphene nanomaterials and miniaturized applications, which has been exemplarily verified through the LIG micro-roll supercapacitors.

A fully integrated wireless microfluidic immunosensing system for portable monitoring of Staphylococcus aureus

The advanced devices that function fully without the need for external accessories are regarded as a pinnacle goal in the design and construction of modern ones. Staphylococcus aureus (S. aureus), a prominent human pathogen, is responsible for causing a wide variety of infections and chronic diseases. Herein, we present the first instance of a fully integrated wireless microfluidic immunosensing system (FIWMIS) capable of conducting point-of-care S. aureus monitoring in real samples of S. aureus-spiked commercial purified drinking water and S. aureus-spiked watermelon juice. The development of the proposed FIWMIS became a reality by conquering significant engineering hurdles in seamlessly integrating a microfluidic unit for liquid sample transport without the need of an external pump, an immunosensing unit for S. aureus monitoring, and an electronic control unit for signal conversion and wireless transmission. Such full integration culminated in a FIWMIS that upholds its pump-free, wireless, and low-cost characteristics for portable monitoring of S. aureus.

Biopolymer-Derived Carbon Materials for Wearable Electronics

Advanced carbon materials are widely utilized in wearable electronics. Nevertheless, the production of carbon materials from fossil-based sources raised concerns regarding their non-renewability, high energy consumption, and the consequent greenhouse gas emissions. Biopolymers, readily available in nature, offer a promising and eco-friendly alternative as a carbon source, enabling the sustainable production of carbon materials for wearable electronics. This review aims to discuss the carbonization mechanisms, carbonization techniques, and processes, as well as the diverse applications of biopolymer-derived carbon materials (BioCMs) in wearable electronics. First, the characteristics of four representative biopolymers, including cellulose, lignin, chitin, and silk fibroin, and their carbonization processes are discussed. Then, typical carbonization techniques, including pyrolysis carbonization, laser-induced carbonization, Joule heating carbonization, hydrothermal transformation, and salt encapsulation carbonization are discussed. The influence of the processes on the morphology and properties of the resultant BioCMs are summarized. Subsequently, applications of BioCMs in wearable devices, including physical sensors, chemical sensors, energy devices, and display devices are discussed. Finally, the challenges currently facing the field and the future opportunities are discussed.

Multifunctional Porous Soft Bioelectronics

Soft bioelectronics, seamlessly interfacing with the human body to enable both recording and modulation of curvilinear biological tissues and organs, have significantly driven fields such as digital healthcare, human-machine interfaces, and robotics. Nonetheless, intractable challenges persist due to the onerous demand for imperceptible, burden-free, and user-centric comfortable bioelectronics. Porous soft bioelectronics is a new way to a library of imperceptible bioelectronic systems, that form natural interfaces with the human body. In this review, we provide an overview of the development and recent advances in multifunctional porous engineered soft bioelectronics, aiming to bridge the gap between living biotic and stiff abiotic systems. We first discuss strategies for fabricating porous, soft, and stretchable bioelectronic materials, emphasizing the concept of materials-level porous engineering for breathable and imperceptible bioelectronics. Next, we summarize wearable bioelectronics devices and multimodal systems with porous configurations designed for on-skin healthcare applications. Moving beneath the skin, we discuss implantable devices and systems enabled by porous bioelectronics with tissue-like compliance. Finally, existing challenges and translational gaps are also proposed to usher further research efforts towards realizing practical and clinical applications of porous bioelectronic systems; thus, revolutionizing conventional healthcare and medical practices and opening up unprecedented opportunities for long-term, imperceptible, non-invasive, and human-centric healthcare networks.

Multi-Electrode Extended Gate Field Effect Transistors Based on Laser-Induced Graphene for the Detection of Vitamin C and SARS-CoV-2

Despite the clinical data showing the importance of ascorbic acid (AA or vitamin C) in managing viral respiratory infections, biosensors for their simultaneous detection are lacking. To address this need, we developed a portable and wireless device for simultaneous detection of AA and SARS-CoV-2 virus by integrating commercial transistors with printed laser-induced graphene (LIG) as the extended gate. We studied the effect of laser printing pass number and showed that with two laser printing passes (2-pass LIG), the sensor sensitivity and limit of detection (LOD) for AA improved by a factor of 1.6 and 12.8, respectively. Using complementary characterization methods, we attribute the improved response to a balanced interplay of crystallinity, defect density, surface area, surface roughness, pore density and diameter, and mechanical integrity/stability. These factors enhance analyte transport, reduce noise/variability, and ensure consistent sensor performance, making 2-pass LIG the most effective material in this work. Our sensors exhibit promising performance for detecting AA with a selective response in the presence of common salivary interfering molecules, with sensitivity and LOD of 73.67 mV/dec and 54.04 nM in 1× phosphate buffered saline and 81.05 mV/dec and 78.34 nM in artificial saliva, respectively. We also showed that functionalization of the 2-pass LIG gate with S-protein antibody enables the detection of SARS-CoV-2 protein antigens with an ultralow LOD of 52 zg/mL─an improvement of more than 10-fold compared to 1-pass LIG─and 4 particles/mL for virion mimics with a selective response against influenza virus and multiple human coronavirus strains. With low signal drift/hysteresis and wireless capabilities, the developed device holds great potential for improving at-home monitoring and clinical decision-making.

Ultrasensitive and Stretchable Strain Sensors Based on Laser-Induced Graphene With ZnO Nanoparticles

Laser-induced graphene (LIG) has attracted considerable attention for its use in flexible and stretchable sensors, owing to its electrical/mechanical properties and scalable fabrication processes. Although laser scanning facilitates the formation of LIG and its strain sensor, the strain-sensing sensitivity enhancement of LIG remains limited by the material's properties and structural design. In this study, we demonstrate a substantial improvement in sensitivity that was achieved by fabricating a LIG using ZnO nanoparticle (NP)-assisted photothermal enhancement. The results show that ZnO NPs selectively reduce the threshold fluence needed to convert polyimide (PI) into LIG. By transferring the LIG formed on PI to poly(dimethylsiloxane), we fabricate a stretchable strain sensor with ultrahigh sensitivity and a gauge factor of 1214 at 10% strain, which is approximately 60 times higher than the gauge factor without ZnO NPs. Using the selective graphenization properties of LIG, a flexible, dual-sided integrated sensor sheet that is equipped with flexible strain and ultraviolet (UV) sensors is demonstrated. This sheet enables simultaneous monitoring of UV intensity and joint bending angles of sports wearable devices. We validated the developed sensors by attaching them to a runner's body to monitor and simulate forefoot and heel strikes, demonstrating the sensor's ultrahigh sensitivity and long-term stability without the need for a camera. These findings highlight the potential of the proposed method for developing multifunctional sensor applications with ultrahigh sensitivity and stability.

Laser-Induced Graphene on Novel Crosslinked Poly(dimethylsiloxane)/Triton X-100 Composites for Improving Mechanical, Electrical and Hydrophobic Properties

Laser-induced graphene (LIG) has become a highly promising material for flexible functional devices due to its robust mechanical stability, excellent electrical properties, and ease of fabrication. Most research has been focused on LIG production on rigid or flexible substrates, with an obvious gap in laser induction of graphene on elastic, stretchable substrates, which limits the scope of application of LIG in flexible electronics. We demonstrate laser induction of graphene on a novel, cross-linked poly(dimethylsiloxane) (PDMS)/Triton X-100 composite substrates. The effect of varying Triton content (1-30 wt.%) on the structural, thermal, surface, nanomechanical, and electrical properties of LIG was systematically studied. Physicochemical characterization confirmed the successful induction of LIG on the surface of PDMS/Triton composites. A higher content of Triton in the PDMS matrix improves the quality of LIG, increases stiffness and hydrophobicity, and somewhat decreases sheet resistance. Similar thermal properties and super-hydrophobicity were observed for LIG/PDMS/Triton materials as compared to their counterparts without LIG. Direct laser irradiation of graphene on the surface of PDMS/Triton composites results in the formation of extremely promising materials, which have great potential for use in flexible electronic devices.

Laser-Induced Graphene-Based Sensors in Health Monitoring: Progress, Sensing Mechanisms, and Applications

The rising global population and improved living standards have led to an alarming increase in non-communicable diseases, notably cardiovascular and chronic respiratory diseases, posing a severe threat to human health. Wearable sensing devices, utilizing micro-sensing technology for real-time monitoring, have emerged as promising tools for disease prevention. Among various sensing platforms, graphene-based sensors have shown exceptional performance in the field of micro-sensing. Laser-induced graphene (LIG) technology, a cost-effective and facile method for graphene preparation, has gained particular attention. By converting polymer films directly into patterned graphene materials at ambient temperature and pressure, LIG offers a convenient and environmentally friendly alternative to traditional methods, opening up innovative possibilities for electronic device fabrication. Integrating LIG-based sensors into health monitoring systems holds the potential to revolutionize health management. To commemorate the tenth anniversary of the discovery of LIG, this work provides a comprehensive overview of LIG's evolution and the progress of LIG-based sensors. Delving into the diverse sensing mechanisms of LIG-based sensors, recent research advances in the domain of health monitoring are explored. Furthermore, the opportunities and challenges associated with LIG-based sensors in health monitoring are briefly discussed.

Pore Engineering in Biomass-Derived Carbon Materials for Enhanced Energy, Catalysis, and Environmental Applications

Biomass-derived carbon materials (BDCs) are highly regarded for their renewability, environmental friendliness, and broad potential for application. A significant advantage of these materials lies in the high degree of customization of their physical and chemical properties, especially in terms of pore structure. Pore engineering is a key strategy to enhance the performance of BDCs in critical areas, such as energy storage, catalysis, and environmental remediation. This review focuses on pore engineering, exploring the definition, classification, and adjustment techniques of pore structures, as well as how these factors affect the application performance of BDCs in energy, catalysis, and environmental remediation. Our aim is to provide a solid theoretical foundation and practical guidance for the pore engineering of BDCs to facilitate the rapid transition of these materials from the laboratory to industrial applications.

Toward Integrated Multifunctional Laser-Induced Graphene-Based Skin-Like Flexible Sensor Systems

The burgeoning demands for health care and human-machine interfaces call for the next generation of multifunctional integrated sensor systems with facile fabrication processes and reliable performances. Laser-induced graphene (LIG) with highly tunable physical and chemical characteristics plays vital roles in developing versatile skin-like flexible or stretchable sensor systems. This Progress Report presents an in-depth overview of the latest advances in LIG-based techniques in the applications of flexible sensors. First, the merits of the LIG technique are highlighted especially as the building blocks for flexible sensors, followed by the description of various fabrication methods of LIG and its variants. Then, the focus is moved to diverse LIG-based flexible sensors, including physical sensors, chemical sensors, and electrophysiological sensors. Mechanisms and advantages of LIG in these scenarios are described in detail. Furthermore, various representative paradigms of integrated LIG-based sensor systems are presented to show the capabilities of LIG technique for multipurpose applications. The signal cross-talk issues are discussed with possible strategies. The LIG technology with versatile functionalities coupled with other fabrication strategies will enable high-performance integrated sensor systems for next-generation skin electronics.