Search Results (375)

High-voltage wiring harnesses in new energy vehicles (NEVs) are susceptible to thermal aging in high-temperature environments, whereas conventional assessment methods are difficult to deploy rapidly. This study combines laser-induced breakdown spectroscopy (LIBS) with random forest (RF) classification to assess thermal aging levels in cross-linked polyethylene (XLPE) insulation. Thirteen laboratory-aged XLPE wiring harness samples were prepared, and 100 single-shot spectra were acquired at fresh positions for each aging level. The specific methodological contribution is the use of class-wise median absolute deviation (MAD) at each wavelength as a variable-selection criterion before RF training. Three models were compared: RF, principal component analysis (PCA) combined with RF (PCA–RF), and MAD combined with RF (MAD–RF). RF achieved 100% internal hold-out accuracy for the non-aged versus 60-day comparison and 84.23% across all 13 aging levels. PCA–RF increased the multiclass accuracy to 87.31%, whereas MAD–RF reached 95.00% under the original exploratory hold-out workflow. These results indicate that wavelength-wise robust dispersion can provide a compact, discriminative representation of the present LIBS dataset. Full article

Real-time tissue identification during laser-guided surgery is a critical unmet need for collateral damage avoidance and margin delineation. Laser-Induced Breakdown Spectroscopy (LIBS) is compatible with pulsed laser surgical systems and offers rapid, label-free elemental analysis. This study presents a machine learning pipeline classifying five ex vivo bovine tissue classes, plus one synthetic null-signal control class, from LIBS spectra, designed to control specimen-level data leakage and class imbalance bias. Key contributions are (i) a ‘peak max over baseline’ aggregation strategy suppressing shot noise while preserving emission peaks; (ii) a repeated, group-based cross-validation protocol (GroupShuffleSplit, N = 10) enforcing specimen-level separation; and (iii) a comparison of 30 configurations (10 classifiers × 3 pipelines). Extra Trees with normalization reached the highest weighted F1-score (0.934 ± 0.118); excluding the synthetic control, five-class scores fall to 0.875–0.915 and the ranking changes, so these are the reference figures for biological tissue discrimination. Support Vector Machines were less accurate but more consistent (0.917 ± 0.069). Acquisition takes approximately 3 s per point; inference is sub-millisecond. With five source animals, the best configuration chosen on the same outer splits, and inner tuning that was not group-aware, these estimates are an exploratory step toward real-time guided surgery. Full article

This paper explores the technical, economic, and environmental viability of producing secondary wrought aluminium alloys from post-consumer scrap. The technical review relates to the industrial-level use of laser-induced breakdown spectroscopy (LIBS) in automated scrap sorting under realistic operating conditions. First, process scrap was used to determine the accuracy of LIBS in sorting and separating wrought aluminium alloys, and then the method was applied to post-consumer scrap streams. The melted products were then analyzed, and their chemical compositions were confirmed using optical emission spectroscopy (OES) to meet the established alloy specifications. The economic analysis compares traditional recycling routes of cast alloys with a second route in which recyclers provide already sorted secondary wrought alloys, with a focus on cost and market feasibility. Simultaneously, an environmental analysis using life cycle analysis (LCA) measures the effects of sorting and manufacturing procedures. The results show that LIBS can effectively sort secondary wrought aluminium under controlled input conditions. The process reaches a break-even point in about five years when a 50% price premium for secondary wrought alloys over mixed scrap is assumed. The method is environmentally beneficial, with the global warming potential per kilogram of aluminium reduced by over 95% compared to the global average. The findings highlight the significant potential of combining advanced sorting technologies, new business models, and sustainability-oriented practices to support the implementation of circular material flows in aluminium recycling. Full article

The growing volume of plastic waste produced has made the need for efficient identification and quantification strategies to detect and identify harmful contaminants, particularly heavy-metals, in industrial plastic-waste streams more urgent than ever. Traditional chemical digestion methods (acid digestion, ICP-MS, or AAS) provide accurate quantification and are time-consuming, costly, and not high-throughput-sorting. Laser-induced breakdown spectroscopy (LIBS) offers several advantages, including rapid real-time analysis, minimal sample preparation, multi-element detection, and efficient elemental characterization. The current review aims to investigate the possibility of using the LIBS technique to detect and quantify some heavy-metals like lead (Pb), cadmium (Cd), chromium (Cr), and arsenic (As) in heterogeneous industrial plastic wastes. The calibration strategies (reference standards) as well as optimization of the signal response and algorithms for data processing, including chemometric models, are evaluated to reduce the limit of detection and enhance analytical accuracy. The results indicate that LIBS can detect heavy-metal contamination at concentrations relevant to regulatory limits and can be scaled for online quality-control monitoring in plastic recycling facilities. In this review, the results have been summarized to support the use of LIBS for waste management towards environmental compliance, reduced use of hazardous materials in recycling products, and reduced health problems due to heavy-metal pollution. Full article

In this study, zirconia specimens were subjected to Al₂O₃ airborne-particle abrasion and Er laser irradiation to investigate their effects on surface characteristics. The treated and untreated zirconia surfaces were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), qualitative elemental analysis by laser-induced breakdown spectroscopy (LIBS), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, XRD analysis, and power spectral density (PSD) analysis. The Er laser-treated group showed the highest mean surface roughness (Sa: 7.763 ± 2.449 µm), compared with the Al₂O₃-treated group (3.640 ± 2.164 μm); however, the differences in Sa among the experimental groups were not statistically significant (Kruskal–Wallis, p = 0.095). Likewise, no statistically significant differences were observed for Sz (one-way ANOVA, p = 0.567). SEM, AFM, and PSD analyses provided complementary information on the morphological and spatial characteristics of the surfaces produced by the different treatments. Under the experimental conditions evaluated, Er laser irradiation produced distinct surface topographic features and a descriptive trend toward higher mean Sa values, but statistical superiority over Al₂O₃ airborne-particle abrasion or the untreated control was not demonstrated. Further studies are required to determine whether these surface modifications translate into functional or clinical benefits. Full article

Handheld Laser-Induced Breakdown Spectrometry (hLIBS) is capable of simultaneous multi-element analysis of a variety of geological materials such as rocks, minerals, ores, soils, sediments, and water. This is a transformative analytical technology that is currently revolutionizing the field of critical mineral exploration studies. By providing real-time, in situ elemental analysis in the field with detection and quantitative determination capabilities for light elements (such as Li, Be, and B), where other handheld techniques like portable XRF struggle, hLIBS empowers geologists to make faster and more informed decisions in the field, significantly accelerating the exploration process from prospecting to target delineation. Several important practical examples of the exploration of critical metals, such as lithium, rare earth elements, copper, cobalt, and titanium, are presented. In particular, the detection capability of indicator minerals and pathfinding elements by hLIBS is extremely valuable for critical mineral exploration studies. Similar instruments have also been successfully used in recent years in challenging environments like space and deep-sea environments. The capability of remotely operated miniature LIBS in hostile environments such as the deep sea, Moon, and Mars is discussed with examples. LIBS has become a key technology for in situ chemical analysis in both space and deep-sea exploration because of its ability to identify elemental composition rapidly and without physical contact. Full article

Synthetic azo dyes may be fraudulently added to paprika powder to intensify color, creating a need for rapid, at-line screening before confirmatory chromatographic analysis. This study evaluated handheld laser-induced breakdown spectroscopy (LIBS) for the screening of sodium-salt azo dye adulteration represented by Allura Red (E129), Ponceau 4R (E124), and Orange II in paprika powder. Paprika was spiked at 17 levels (0–6% w/w) in three independent batches, mixed with Al₂O₃ binder, dried, pelletized, and measured with a portable SciAps Z-903 under argon in the broad 190–950 nm region. The calibration models were developed using SNV-pretreated spectra and partial least squares regression with test-set validation based on a 70/30 split by concentration level. The main concentration-related response was increased Na emission, consistent with the sodium-salt form of the dyes, while Al emission showed an inverse matrix-/plasma-coupled trend despite the constant binder fraction. Full-spectrum models gave R²_TSV values of 0.845–0.875 and RMSETSV values of 0.638–0.716% (w/w), using 4–5 latent variables. Outlier trimming improved prediction for Allura Red and Orange II, while regression coefficient-uncertainty variable selection reduced model complexity to 2–3 latent variables with dye-dependent effects. Since sodium-salt azo dyes are commonly used as adulterants in paprika powder, the Na-dominated LIBS response demonstrates good potential for rapid at-line screening. Nevertheless, as LIBS does not directly confirm dye identity, complementary confirmatory analysis using spectroscopic or chromatographic methods remains necessary. Full article

Reliable estimation of biochar’s calorific value is essential for optimizing its use as a renewable energy source. Traditional bomb calorimetry provides accurate measurements but is hindered by its destructive, time-consuming nature, limiting the high-throughput screening capabilities needed for large-scale deployment. In this study, an innovative, non-destructive approach utilizing laser-induced breakdown spectroscopy (LIBS) combined with advanced multivariate analysis is presented for predicting the Higher Heating Value (HHV) of biochar derived from pine and beech biomass. The developed empirical model incorporates spectral signatures of key elements: carbon, hydrogen, nitrogen, sulfur, and oxygen. Model validation using 36 independent biochar samples revealed a statistically significant correlation between experimentally measured and LIBS-predicted HHVs (p-value = 0.045, t-statistic = 2.08). The developed model yielded a mean absolute error (MAE) of 1.33 MJ kg⁻¹ and a root mean square error (RMSE) of 1.72 MJ kg⁻¹. The findings demonstrate the feasibility of using LIBS-derived elemental data for rapid HHV estimation and provide a basis for further model refinement through the inclusion of additional biochar types and calibration datasets. The model effectively captures the complex nonlinear relationships between spectral features and energy content, addressing the heterogeneity inherent in biochar matrices. These findings highlight LIBS’s potential as a rapid, scalable, and environmentally sustainable tool for real-time biochar evaluation. Implementing this approach could significantly accelerate biomass resource assessment, optimize bioenergy production, and advance sustainable energy management strategies aligned with global environmental goals. Full article

Germanium (Ge) is a high-tech critical metal typically hosted at trace levels in sphalerite, making its detection and characterization challenging in both primary ores and mine residues. This study presents a multi-scale analytical workflow combining laser-induced breakdown spectroscopy (LIBS), electron probe micro-analysis (EPMA), and multivariate statistics to detect, map and quantify Ge distribution in a representative Pb-Zn sample from the Les Malines deposit (France). µ-LIBS mapping enables rapid centimeter-scale screening at 15 µm resolution and identifies Ge-bearing domains over large areas, which are subsequently investigated at micrometer scale using EPMA chemical mapping and quantitative analyses. Results reveal a strong µm-scale heterogeneity of Ge distribution within sphalerite, with Ge systematically concentrated in an Fe-rich intermediate zonation associated with prismatic growth textures, while Cu/Cd/Ag are enriched in distinct collomorph domains. Multivariate statistical analyses (correlation matrices and PCA) confirm a strong geochemical structuring opposing an Fe/Ge association against a Cu/Cd/Ag pole. These findings demonstrate that Ge incorporation is controlled by localized growth conditions rather than bulk composition. The proposed workflow provides an efficient and scalable framework for exploration, enabling rapid targeting of critical metal enrichments and supporting their extension to multiple mineralization stages, Pb-Zn deposits, and other high-tech critical metals (HTCMs) such as Ga and In. Full article

This manuscript will present an advancement of transformative research that has been conducted at Oak Ridge National Laboratory (ORNL) over a 25-year period (2000–2025) on a variety of environmental and biological matrices. These investigations derived a fundamental understanding of how elemental detection and analysis of these matrices led to the knowledge and discovery of natural processes in plants and the environment. Each project led to the initiation of a new research area which unearthed awesome and novel breakthroughs. Highlights are listed below: 1. The preliminary research at ORNL centered on the detection of aerosols utilizing Laser-induced Breakdown Spectroscopy (LIBS) technology. The Clean Air Act Amendment (CAAA) of 1990 highlighted the importance of identifying hazardous air pollutants (HAPs) due to their impact on environmental and human health, thereby underscoring the need to detect various toxic elements. Research in aerosol chemistry aimed to identify these harmful elements released by factories during periods of increased emissions in their manufacturing processes. LIBS emerged as the most effective method for real-time, in situ measurements of metal species in both gaseous and aerosol phases. 2. An understanding of the presence of total carbon in soils gives perspective on how to develop carbon sequestration strategies. The recognition that carbon sinks can evolve back to carbon sources to emit back to the atmosphere was an important consideration. Also, the concentration of carbon in soil indicates the health of land areas for growing crops successfully. 3. The direct detection of most of the elements in a wood sample in a single emission spectrum, without sample preparation, encouraged the research to use the LIBS technique for preservative treated wood coupled with use of multivariate statistical methodology. Additionally, it encouraged the researchers to try to differentiate natural woods from different parts of the country, and it was successfully demonstrated that LIBS coupled with MVA analysis could differentiate wood of different species from each other and of similar species grown in different environments based on their elemental spectra. This was a breakthrough since it revealed a systematic approach to connect elemental scarcity and abundance to either drought or typical rainfall conditions for the hardwood trees grown in specific areas. 4. Furthermore, the research progressed to reveal physiological and developmental processes contributing to biomass production such that the variation in leaf elemental composition increases our understanding of terrestrial nutrient cycles, as well as tracking the transfer of toxic elements from soils to living organisms. 5. Recently another breakthrough viz., ionomics initiated the correlation of elements to specific genes, uncovering the function that the element performed in the plant. More recently, this has been extended from plants to fungi as well as fungi growing in symbiotic relations with plants. Full article

Second-generation high-temperature superconducting tapes (2G HTS; SuperPower Inc., Glenville, NY, USA) based on GdBCO (GdBa₂Cu₃O_7−δ, where δ denotes oxygen deficiency) were aged at −26.4 °C, +2 °C, and room temperature (RT) to evaluate the degradation of their superconducting properties. HTS tapes stored at RT exhibited a significantly higher deterioration rate compared to those maintained at lower temperatures. Laser-induced breakdown spectroscopy (LIBS) analysis demonstrated a gradual reduction in the effective chemical depth-profiling length over time, indicating a correlation between the degradation mechanism and the reduction in the effective volumetric density of the GdBCO superconducting layer. These findings imply that oxygen diffusion or redistribution processes substantially contribute to the long-term degradation of GdBCO-based HTS tapes. Full article

Laser-induced breakdown spectroscopy (LIBS) offers rapid, in situ, and multi-element detection, and therefore shows strong potential for quality monitoring of metal powders in additive manufacturing. However, direct LIBS analysis of flowing metal powders is often affected by particle splashing, unstable laser–particle coupling, and plasma fluctuations, which reduce signal repeatability and detection reliability. To address these issues, this study developed an integrated measurement and classification framework for identifying cross-contamination in additive-manufacturing metal powders. A stable powder particle stream was generated through vibratory feeding and particle-flow focusing, while a hollow quartz tube with a side opening was introduced to provide cylindrical spatial confinement, thereby improving the stability of laser–particle interaction and enabling in situ spectral acquisition without pellet preparation. TC4 powder was used as the base material and AlSi10Mg powder as the contaminant, and samples with contamination levels of 0, 0.5, 1, 2, and 5 wt.% were prepared. Two independent batches of single-shot LIBS spectra were collected. To reduce the influence of strong spectral fluctuations, outlier spectra were removed using full-spectrum total-intensity quantile filtering, followed by asymmetric least-squares baseline correction and standard normal variate transformation. PCA combined with multiple machine-learning models was then applied for contamination identification. The results showed that LIBS spectra at different contamination levels exhibited distinguishable distributions in principal-component space, and the spectral differences between clean and contaminated powders became more pronounced with increasing contamination level. In binary classification, several models achieved high classification accuracy at medium and high contamination levels, while PCA-SVM-RBF showed the best performance at low concentrations. In five-class cross-validation, the 5 wt.% class exhibited the clearest decision boundary, whereas confusion remained among low and adjacent contamination levels, indicating that contamination-induced spectral responses followed a more continuous transition. These results demonstrate that the proposed spatially confined particle-flow LIBS framework combined with machine-learning classification can effectively achieve rapid identification of cross-contamination in additive-manufacturing metal powders and provides a feasible technical route for online powder quality monitoring. Full article

Rapid and efficient elemental characterization of lignocellulosic biomass, such as grapevine cane residues, is essential for its effective utilization in energy and material applications; however, conventional analytical methods typically require extensive sample preparation and are therefore not suitable for rapid screening purposes. In this study, laser-induced breakdown spectroscopy (LIBS) based on TEA CO₂ laser ablation is applied as a direct and minimally destructive approach for the analysis of grapevine cane biomass. Emission spectra recorded in the 190–780 nm range enabled qualitative identification of the elements present in the biomass, supporting the applicability of LIBS for multi-element analysis of complex solid matrices. Quantitative determination of Mg, Ca, K, and Na was achieved using an external calibration approach with solid-spiked standards, yielding good linearity (R² = 0.976–0.990), with concentrations in good agreement with reference ICP–OES measurements. Plasma diagnostics indicated a temperature of approximately 10,500 K and an electron number density on the order of 10¹⁶ cm⁻³, supporting the assumption of local thermodynamic equilibrium (LTE) conditions. The results demonstrate that LIBS provides a rapid and practical tool for direct elemental screening of vine shoot biomass, with potential application in the assessment of agricultural residues for carbon-based material production and related valorization pathways. Full article

Rare earth element (REE) detection sensitivity with minimal sample damage is exciting. Laser-induced breakdown spectroscopy (LIBS) with a typical methodology is a useful diagnostic tool, but often shows poor REE sensitivity. This study presents the qualitative, quantitative, and classification analysis of REE-bearing ore samples that contain multiple elements from the lanthanoid (Ln) group (e.g., La, Ce, Nd, Sm, and Gd) using the LIBS technique, and the results are compared with those obtained using a magnetic-field-assisted LIBS (MFA-LIBS) system. The LIBS spectrum was recorded using a Nd:YAG Laser with a 532 nm emission wavelength, a 5 ns pulse duration, and a 10 Hz repetition rate. Optical regions exhibiting the strongest emission lines of REEs were identified, followed by MFA-LIBS to improve the qualitative signatures of the elements of interest. MFA-LIBS also assists in confirming signal enhancement for Sm and Gd, which were unidentified with a conventional LIBS setup. Quantitative analysis was performed using a calibration-free and magnetic-field-assisted LIBS (CF-MF-LIBS) method. La, Ce, and Nd concentrations were estimated to be from 1 to 3 wt.%, whereas Sm and Gd were detected within 0.5 wt.%. The results obtained using CF-MF-LIBS were compared with those obtained using the X-ray fluorescence spectroscopy (XRF) technique, showing good agreement between the LIBS/XRF techniques. Further, the limit of detection (LOD) of the REEs using in-house prepared samples was estimated, and the results were compared with those previously reported in the literature. Furthermore, classification analysis of REE ores based on compositional variations was achieved using principal component analysis (PCA). The first two principal components (PCs) with maximum spectral variance, such as PC1~74.5% and PC2~14.5%, were considered for the clustering, and ellipses with 95% confidence using major (x) and minor (y) axes were created to explore outliers. Therefore, the CF-MF-LIBS method in combination with PCA demonstrates a rapid, robust, and effective methodology for the detection, quantification, and classification investigation of REE-bearing ores. Full article

In response to the demands for planetary material detection, in this study, we propose an optical system for a compact remote Raman–LIBS (CRBS, Laser-Induced Breakdown Spectroscopy) combined spectrometer based on liquid lens focusing. This system adopts a design approach incorporating liquid lens focusing, a shared pulsed excitation source, and a common optical path for both transmission and reception. Compared to existing international combined Raman–LIBS spectrometer systems, the proposed optical system is more compact and achieves integrated Raman and LIBS detection capabilities, thereby facilitating system miniaturization and enhancing detection efficiency. This system represents a promising approach for compact, robust remote surface analysis instruments for terrestrial and planetary science. This study provides a theoretical foundation for achieving stable in-orbit detection in lunar material exploration and other long-distance signal detection missions. Full article