Review of Laser-Induced Graphene Sensors

By Dr. Noopur JainReviewed by Louis CastelSep 4 2025

In a recent review article published in the journal Analytical Methods, researchers have been investigating laser-induced graphene (LIG) sensors, with a focus on their fast, eco-friendly fabrication using laser processing techniques. The study underscores how key laser parameters, such as power, wavelength, and scanning speed, directly influence the quality, surface morphology, and electrochemical performance of LIG. Thanks to their versatility, low production cost, and environmentally sustainable manufacturing, LIG-based sensors hold strong potential across a range of applications, including healthcare diagnostics, environmental monitoring, and smart infrastructure.

Image credit: Marco de Benedictis/Shutterstock.com

Background

Graphene, a single layer of carbon atoms arranged in a hexagonal lattice, possesses exceptional electrical, mechanical, and chemical properties. Traditional graphical material synthesis often involves complex chemical processes and high-temperature treatments, which are resource-intensive and less environmentally friendly. Laser processing emerges as a promising alternative, leveraging optically driven reactions to convert carbon-rich substrates (mainly polyimide films) directly into graphene patterns.

The optical aspect is central here: lasers can be precisely controlled in terms of wavelength, power density, pulse duration, and scanning velocity, enabling tailored local heating and ablation processes. These parameters influence the physical and chemical transformations within the substrate, such as carbonization, defect formation, and functionalization, all of which directly affect the electrochemical properties of the resulting LIG.

Studies Highlighted in the Review

Variations in laser wavelength (commonly infrared or ultrafast pulsed UV/visible lasers), power, and scanning speed can produce graphene with different morphologies, ranging from monolayer to multilayer structures, and introduce defects or edge sites beneficial for electrochemical reactions. For example, increasing laser power boosts localized heating, which improves graphitization. If not carefully controlled, it can however cause damage or lead to excessive material ablation. Similarly, using shorter pulse durations often produces graphene with more structural defects, a characteristic that can actually enhance performance in certain sensing applications.

Real-time optical diagnostics, such as inline Raman spectroscopy and optical emission spectroscopy, are employed to monitor the transformation process during laser irradiation. Such techniques help optimize laser parameters to achieve reproducible, high-quality LIG with desirable features like abundant edge defects and porosity. The review emphasizes that careful control of the laser’s optical properties enables consistent fabrication of sensitive and selective sensors.

While polyimide remains the main substrate, studies have investigated alternative materials like paper or textiles, with corresponding adjustments in laser wavelength to facilitate efficient energy absorption and carbonization. Optical absorptivity at different wavelengths plays a key role in the efficiency of graphene formation. Shorter wavelengths, such as those in the ultraviolet range, enable highly localized energy deposition. This can result in finer structural features and increased surface defect densities, both of which are beneficial for enhancing sensor sensitivity.

Combining laser processing with post-fabrication optical characterization, such as Raman spectroscopy, enables detailed analysis of defect structures, crystalline quality, and functional groups. Such insights are critical for tailoring LIG for specific sensing tasks (e.g., biosensing, electroanalysis of heavy metals or biomolecules), where surface chemistry and defect sites play pivotal roles.

The review highlights a variety of LIG-based sensors, covering glucose, cardiac biomarkers, heavy metals, and environmental pollutants, produced using carefully optimized optical parameters. In many cases, enhanced sensitivity is achieved by tuning laser settings to create higher defect densities or increased porosity, both of which are structurally engineered through precise optical control.

Discussion

The review emphasizes that optical control is central to shaping both the micro- and macro-structure of LIG, which directly influences its electrochemical behavior. By carefully adjusting laser wavelength and power, researchers can fine-tune surface chemistry, defect density, porosity, and the formation of edge sites, all critical factors in optimizing sensor performance.

Laser optics also influence fabrication reproducibility and scalability. For industrial deployment, consistent laser parameters ensure uniform sensor quality, while advances in optical monitoring (such as in situ spectroscopy) facilitate process optimization. Furthermore, the capacity to fine-tune optical parameters opens avenues for integrating LIG sensors with other optoelectronic devices or embedding them into flexible, wearable systems.

The theoretical understanding correlates laser-induced thermal effects, dictated primarily by optical properties, with the resulting microstructure. The review advocates for more research into laser wavelength-dependent absorption mechanisms, real-time optical diagnostics, and multiscale modeling to predict outcomes. Such research can minimize trial-and-error approaches, leading to more controlled, high-quality graphene production.

Conclusion

Laser optics stands at the core of the rapid, eco-friendly fabrication and functional tuning of LIG sensors. The review underscores that mastery over optical parameters (wavelength, power density, pulse duration, and laser trajectory) facilitates precise microstructural control, thereby enhancing sensor sensitivity, selectivity, and reproducibility. Future prospects involve integrating real-time optical monitoring tools to achieve standardized, scalable manufacturing processes. The continued development of optically optimized laser systems, coupled with comprehensive understanding of light-material interactions, will further solidify LIG as a key material platform for advanced electrochemical sensing, biomedical diagnostics, and beyond.