3D Microscopy Research Articles

OoCount: A Machine-Learning Based Approach to Mouse Ovarian Follicle Counting and Classification.

The number and distribution of follicles in each growth stage provides a reliable readout of ovarian health and function. Leveraging techniques for three-dimensional imaging of ovaries in toto has the potential to uncover total, accurate ovarian follicle counts. Due to the size and holistic nature of these images, counting oocytes is time consuming and difficult. The advent of machine-learning algorithms has allowed for the development of ultra-fast, automated methods to analyze microscopy images. In recent years, these pipelines have become more accessible to non-specialists. We used these tools to create OoCount, a high-throughput, open-source method for automatic oocyte segmentation and classification from fluorescent 3D microscopy images of whole mouse ovaries using a deep-learning convolutional neural network (CNN) based approach. We developed a fast tissue-clearing and imaging protocol to obtain 3D images of whole mount mouse ovaries. Fluorescently labeled oocytes from 3D images were manually annotated in Napari to develop a training dataset. This dataset was used to retrain StarDist using a CNN within DL4MicEverywhere to automatically label all oocytes in the ovary. In a second phase, we utilize Accelerated Pixel and Object Classification, a Napari plugin, to sort oocytes into growth stages. Here, we provide an end-to-end pipeline for producing high-quality 3D images of mouse ovaries and obtaining follicle counts and staging. We demonstrate how to customize OoCount to fit images produced in any lab. Using OoCount, we obtain accurate oocyte counts from each growth stage in the perinatal and adult ovary, improving our ability to study ovarian function and fertility.

3D Single-Molecule Super-Resolution Imaging of Microfabricated Multiscale Fractal Substrates for Calibration and Cell Imaging.

Microstructures arrayed over a substrate have shown increasing interest due to their ability to provide advanced 3D cellular models, which open up new possibilities for cell culture, proliferation, and differentiation. Still, the mechanisms by which physical cues impact the cell phenotype are not fully understood, hence the necessity to interrogate cell behavior at the highest resolution. However, cell 3D high-resolution optical imaging on such microstructured substrates remains challenging due to their complexity as well as axial calibration issues. In this work, we address this issue by leveraging the geometrical characteristics of fractal-like structures, which serve as axial calibration tools and modulate cell growth. To this end, we use multiscale 3D SiO2 substrates consisting of spatially arrayed octahedral features of a few micrometers to hundreds of nanometers. Through optimizations of both the structures and optical imaging conditions, we demonstrate the potential of these 3D multiscale structures as an alternative to electron microscopy for material imaging but also as calibration tools for 3D super-resolution microscopy. We used their multiscale and known geometry to perform lateral and axial calibrations in 3D single-molecule localization microscopy (SMLM) and assess imaging resolutions. We then utilized these substrates as a platform for high-resolution bioimaging. As a proof of concept, we cultivate human mesenchymal stem cells on these substrates, revealing very different growth patterns compared to flat glass. Specifically, the spatial distribution of cytoskeleton proteins is vastly modified, as we demonstrate with a 3D SMLM assessment.

Spherical harmonics texture extraction for versatile analysis of biological objects.

The characterization of phenotypes in cells or organisms from microscopy data largely depends on differences in the spatial distribution of image intensity. Multiple methods exist for quantifying the intensity distribution - or image texture - across objects in natural images. However, many of these texture extraction methods do not directly adapt to 3D microscopy data. Here, we present Spherical Texture extraction, which measures the variance in intensity per angular wavelength by calculating the Spherical Harmonics or Fourier power spectrum of a spherical or circular projection of the angular mean intensity of the object. This method provides a 20-value characterization that quantifies the scale of features in the spherical projection of the intensity distribution, giving a different signal if the intensity is, for example, clustered in parts of the volume or spread across the entire volume. We apply this method to different systems and demonstrate its ability to describe various biological problems through feature extraction. The Spherical Texture extraction characterizes biologically defined gene expression patterns in Drosophila melanogaster embryos, giving a quantitative read-out for pattern formation. Our method can also quantify morphological differences in Caenorhabditis elegans germline nuclei, which lack a predefined pattern. We show that the classification of germline nuclei using their Spherical Texture outperforms a convolutional neural net when training data is limited. Additionally, we use a similar pipeline on 2D cell migration data to extract polarization direction, quantifying the alignment of fluorescent markers to the migration direction. We implemented the Spherical Texture method as a plugin in ilastik to provide a parameter-free and data-agnostic application to any segmented 3D or 2D dataset. Additionally, this technique can also be applied through a Python package to provide extra feature extraction for any object classification pipeline or downstream analysis.

Rapid iPSC-derived neuromuscular junction model uncovers motor neuron dominance in amyotrophic lateral sclerosis cytopathy

The neuromuscular junction (NMJ) is essential for transmitting signals from motor neurons (MNs) to skeletal muscles (SKMs), and its dysfunction can lead to severe motor disorders. However, our understanding of the NMJ is limited by the absence of accurate human models. Although human induced pluripotent stem cell (iPSC)-derived models have advanced NMJ research, their application is constrained by challenges such as limited differentiation efficiency, lengthy generation times, and cryopreservation difficulties. To overcome these limitations, we developed a rapid human NMJ model using cryopreserved MNs and SKMs derived from iPSCs. Within 12 days of coculture, we successfully recreated NMJ-specific connectivity that closely mirrors in vivo synapse formation. Using this model, we investigated amyotrophic lateral sclerosis (ALS) and replicated ALS-specific NMJ cytopathies with SOD1 mutant and corrected isogenic iPSC lines. Quantitative analysis of 3D confocal microscopy images revealed a critical role of MNs in initiating ALS-related NMJ cytopathies, characterized by alterations in the volume, number, intensity, and distribution of acetylcholine receptors, ultimately leading to impaired muscle contractions. Our rapid and precise in vitro NMJ model offers significant potential for advancing research on NMJ physiology and pathology, as well as for developing treatments for NMJ-related diseases.

Nanoscale visualization of crack tips inside molten corium-concrete interaction debris using 3D-FIB-SEM with multiphase positional misalignment correction.

Characterizing molten corium-concrete interaction (MCCI) fuel debris in Fukushima reactors is essential to develop efficient methods for its removal. To enhance the accuracy of microscopic observation and focused ion beam (FIB) microsampling of MCCI fuel debris, we developed a three-dimentional FIB scanning electron microscopy (SEM) technique with a multiphase positional misalignment (MPPM) correction method. This system automatically aligns voxel positions, corrects contrast, and removes artifacts from a series of over 500 SEM images. The MPPM correction method, which focuses on time-modulated contrast, considerably reduces charge-up artifacts in glass phases, enabling 3D morphological observation and analytical transmission electron microscopy of crack tips in two types of MCCI debris at the 3D/nanoscale for the first time. In the Fe-ZrSiO4-based debris, metallic balls composed of Fe, Cr2O3, and ZrO2 with dimples on the surface of about 2-58 µm in diameter were observed at the crack tips. In the (Zr, U)SiO4 based debris, a core-shell structure composed of a (U, Zr)O2 core with a diameter of about 1-5 μm and a (Zr, U)SiO4 shell with a diameter of about 2-9 μm in complex molten corium-concrete interaction fuel debris at the crack tips.

Microelectrothermoforming (μETF): one-step versatile 3D shaping of flexible microelectronics for enhanced neural interfaces

Increasing the proximity of microelectrode arrays (MEA) to targeted neural tissues can establish efficient neural interfaces for both recording and stimulation applications. This has been achieved by constructing protruding three-dimensional (3D) structures on top of conventional planar microelectrodes via additional micromachining steps. However, this approach adds fabrication complexities and limits the 3D structures to certain shapes. We propose a one-step fabrication of MEAs with versatile microscopic 3D structures via “microelectrothermoforming (μETF)” of thermoplastics, by utilizing 3D-printed molds to locally deform planar MEAs into protruding and recessing shapes. Electromechanical optimization enabled a 3D MEA with 80 μm protrusions and/or recession for 100 μm diameter. Its simple and versatile shaping capabilities are demonstrated by diverse 3D structures on a single MEA. The benefits of 3D MEA are evaluated in retinal stimulation through numerical simulations and ex vivo experiments, confirming a threshold lowered by 1.7 times and spatial resolution enhanced by 2.2 times.

Effect of a chemically-modified-curcumin on dental resin biodegradation.

Previous studies have shown Streptococcus mutans (S. mutans) esterase is a key mediator of dental composite biodegradation, which can contribute to recurrent caries. This study is to investigate the inhibitory effects of a novel Chemically-Modified-Curcumin (CMC 2.24) on esterase activities and related dental material biodegradation. Dental adhesive materials and composite resins were incubated in S. mutans suspension with CMC 2.24 and other compounds, including doxycycline, Chemically-Modified-Tetracycline (CMT-3), and curcumin for 4 weeks. The pre- and post-incubation surface roughness were evaluated by either laser diffraction pattern and/or a 3D laser scanning microscope. Esterase enzyme inhibition assays were performed with the same test groups and activities were determined spectrophotometrically. Among all experimental groups, CMC 2.24 significantly reduced surface roughness of dental composite (p < 0.01) and adhesive (p < 0.01) materials compared to bacteria-only group. Additionally, CMC 2.24 reduced porcine esterase activity by 46.5%, while other compounds showed minimal inhibition. In the S. mutans esterase assay, CMC 2.24 showed inhibition of 70.0%, while other compounds showed inhibition ranging from 19% to 36%. Our study demonstrated that CMC 2.24 inhibited biodegradation of dental composite material more effectively than its mother compound, curcumin. Moreover, the mechanism of this biodegradation was likely mediated through bacterial esterase activity. Doxycycline achieved similar inhibition by completely eradicating S. mutans with its antibiotic action; hence, it is not recommended for long-term use.

Evaluating the Use of a 3D Exoscope to Improve Ergonomics in Cleft Surgery.

The aim of this study was to investigate and compare the technical feasibility, ergonomics, and educational value of the 3D exoscope in comparison with traditional and prism loupes in cleft surgery. A variety of cleft and pharyngeal operations were performed with the VITOM® 3D exoscope (Karl Storz GmbH, Tuttlingen, Germany), traditional/prism loupes, and microscope. The cervical neck angulation of the operating surgeon was recorded in real-time with an inertia measurement unit system (Mbient, San Francisco, USA) and experiences of the surgeon and assistant were prospectively evaluated with 5-point Likert scales. National Health Service, England. Eleven patients were recruited in whom 12 procedures were performed. Two main surgeons, 3 assistant surgeons, and 3 scrub nurses were recruited into the study. Four procedures were performed with the VITOM® 3D exoscope, and as the comparison groups, 5 procedures were performed with normal loupes, 3 with prism loupes, and 2 were done in combination with a microscope and analyzed separately. Neck angle measurements and feedback from surgeons, assistants, and scrub nurses. The VITOM® system improved surgeon ergonomics with reduced procedure time in cervical flexion when compared to the other visualization methods (versus loupes, P &lt; .01, and prism, P &lt; .01). The VITOM® system also scored favorably in terms of image-related fields, ergonomics, and ease of use. Use of the 3D exoscope in cleft surgery yielded improved experiences for both surgeons, assistants, and nurses in comparison with loupes and microscopes without increasing operating time.

Tribological behavior investigation of enset/sisal hybrid reinforced composites

Abstract Easy availability, biodegradability and exceptional performance of natural fibers are among the attractive factors for their wide utilization. However, several factors such as fiber type, shape and size of fibers, fiber-matrix ratios, reinforcement orientation with respect to the loading direction, preparation method and type of treatment used highly influence their performance. The present study investigates the tribological behavior of polyester composites developed by hybridizing two locally available inexpensive plant fibers: enset and sisal. Both woven and unidirectional 5 wt% alkali treated hybrid fibers with 1:1 ratio was used to develop the hybrid composite using hand lay-up and compression molding. The tribological property was tested using pin-on-disc tribo-testing machine. The wear condition was studied in dry condition by varying the applied load (10, 20 and 30 N) and sliding speed (0.5, 1 and 1.5 m/s). Analysis of the morphology of the worn surface was conducted using 3D microscopy scanning electron microscopy images. The coefficient of friction and the wear rate results indicate the suitability of the selected hybrid composite for use as frictional material such as brake applications.

Enhanced Tribological and Mechanical Properties of Copper-Modified Basalt-Reinforced Epoxy Composites.

The increasing demand for high-performance materials in industrial applications highlights the need for composites with enhanced mechanical and tribological properties. Basalt fiber-reinforced polymers (BFRP) are promising materials due to their superior strength-to-weight ratio and environmental benefits, yet their wear resistance and tensile performance often require further optimization. This study examines how adding copper (Cu) powder to epoxy resin influences the mechanical and tribological properties of BFRP composites. Epoxy matrices, modified with 5%, 10%, and 15% weight fractions (wf.%) of copper powder, were reinforced with BFRP-type fabric, using a vacuum bag manufacturing method. Mechanical tests, including bending and tensile tests, showed notable improvements in tensile strength and flexural modulus due to copper addition, with higher copper (Cu) content enhancing ductility. Tribological tests using a pin-on-disk tribometer revealed reduced wear rates and an optimized coefficient of friction. Statistical analysis and 3D microscopy identified wear mechanisms such as delamination and protective copper film formation. The results highlight the significant potential of copper-modified BFRP composites for applications demanding superior mechanical and tribological performance.

Color-multiplexed 3D differential phase contrast microscopy with optimal annular illumination.

Quantitative phase imaging (QPI) has become a valuable tool in the field of biomedical research due to its ability to quantify refractive index variations of live cells and tissues. For example, three-dimensional differential phase contrast (3D DPC) imaging uses through-focus images captured under different illumination patterns deconvoluted with a computed 3D phase transfer function (PTF) to reconstruct the 3D refractive index. In conventional 3D DPC with semi-circular illumination, partially spatially coherent illumination often diminishes phase contrast, exacerbating inherent noise, and can lead to a large number of zero values in the 3D PTF, resulting in strong low-frequency artifacts and deteriorating imaging resolution. To overcome the above drawbacks, we obtain the conditions for acquiring the optimal 3D PTF based on the analysis of the 3D imaging model and the derivation of the 3D PTF calculation process and propose a 3D DPC microscopy based on optimal annular illumination. The proposed optimal annular illumination pattern minimizes the missing frequency components in the 3D Fourier space, resulting in the best noise-robustness and significantly increased phase contrast. To expedite imaging speed, we utilize a 1/2 annular multiplexed illumination, reducing data acquisition volume by 75%. The 3D refractive index tomography of a simulated 3D phase object, unstained tongue sections, and oral epithelial cells demonstrates that our proposed method achieves the above advantages. In conclusion, we demonstrate a novel 3D DPC microscope that only requires replacing the illumination of a commercial microscope with a programmable LED array. The accurate 3D refractive index tomography and the compactness of the system setup allow the method to play a significant role in the biomedical field.

3D Ultrasound Localization Microscopy of the Nonhuman Primate Brain

Haemodynamic changes occur in stroke and neurodegenerative diseases. Developing imaging techniques allowing the invivo visualisation and quantification of cerebral blood flow would help better understand the underlying mechanism of these cerebrovascular diseases. 3D ultrasound localization microscopy (ULM) is a recently developed technology that can map the microvasculature of the brain at large depth and has been mainly used until now in rodents. In this study, we tested the feasibility of 3D ULM of the nonhuman primate (NHP) brain with a single 256-channel programmable ultrasound scanner. We achieved a highly resolved vascular map of the macaque brain at large depth (down to 3cm) in presence of craniotomy and durectomy using an 8-MHz multiplexed matrix probe. We were able to distinguish vessels as small as 26.9 μm. We also demonstrated that transcranial imaging of the macaque brain at similar depth was feasible using a 3-MHz probe and achieved a resolution of 60 μm. This work paves the way to clinical applications of 3D ULM. In particular, transcranial 3D ULM in humans could become a tool for the non-invasive study and monitoring of the brain cerebrovascular changes occurring in neurological diseases. This work was supported by the New Frontier in Research Fund (NFRFE-2022-00590), by the Canada Foundation for Innovation under grant 38095, by the Natural Sciences and Engineering Research Council of Canada (NSERC) under discovery grant RGPIN-2020-06786, by Brain Canada under grant PSG2019, and by the Canadian Institutes of Health Research (CIHR) under grant PJT-156047 and MPI-452530. Computing support was provided by the Digital Research Alliance of Canada.

Regulation of NHE3 subcellular localization in epididymal principal cells: pH, cyclic adenosine 3,5 monophosphate (cAMP), and adenosine signaling.

The epididymis creates an optimal acidic luminal environment for sperm maturation and storage. In epididymal principal cells (PCs), proton secretion is activated by the accumulation of the sodium-proton exchanger type 3, NHE3 (SLC9A3), in apical stereocilia. PCs also secrete ATP, which is hydrolyzed into adenosine by ectonucleotidases. Adenosine has opposite effects depending on which purinergic receptors it activates. Activation of ADORA1 (A1) and ADORA3 (A3) receptors decreases intracellular cAMP (cAMP), while activation of ADORA2A (A2A) and ADORA2B (A2B) receptors increases cAMP. In other epithelia, cAMP triggers NHE3 internalization from the apical membrane. Here, we examined the roles of pH, cAMP, and adenosine (via A3, A2A, and A2B receptors) in the subcellular localization of NHE3 in PCs. 3D immunofluorescence confocal microscopy was used to visualize NHE3 in stereocilia or intracellular vesicles. Single confocal microscopy images superimposed with bright-field imaging was used to quantify NHE3 subcellular localization. The lumen of the cauda (Cd) epididymis of C57Bl/6Ncrl mice was perfused in vivo at pH 6.0 and 7.8. The effect of a permeant analog of cAMP (cpt-cAMP) was studied at pH 7.8, while the effect of adenosine was investigated at pH 6.0. Expression of A2A, A2B, and A3 was examined by immunofluorescence, and their respective role was evaluated by using specific agonists and antagonists at different luminal pH. Immunofluorescence for clathrin, an endosomal marker, was examined at pH 7.8 with and without an A2B agonist. At an acidic pH perfusion solution of 6.0, NHE3 was predominantly localized intracellularly, whereas an alkaline pH of 7.8 promoted its accumulation in apical stereocilia. Perfusion with cpt-cAMP at pH 7.8 reduced the amount of NHE3 in stereocilia. Immunolabeling showed the localization of A3, A2A, and A2B receptors in the apical membrane of epithelial cells in the Cd epididymis. Adenosine and an A3 agonist increased NHE3 stereocilia accumulation at pH 6.0, and the adenosine effect was abolished with an A3 antagonist. An A2A agonist had no effect on NHE3 localization, while an A2B agonist decreased the amount of NHE3 in stereocilia observed at pH 7.8. A concomitant increase in intracellular labeling for clathrin was induced by the A2B agonist at pH 7.8. Our study indicates that in the Cd epididymis, NHE3 localization in PCs is modulated by luminal pH, cAMP, and adenosine receptor signaling. Acidic pH promotes NHE3 internalization, while alkaline pH facilitates its accumulation in stereocilia. Activation of A3 by luminal adenosine maintains NHE3 on the cell surface. Conversely, A2B activation by adenosine induces NHE3 internalization. We propose that the distinct effects mediated by these receptors are the consequence of their opposite effect on cAMP signaling. This intricate interplay of pH and adenosine highlights some of the regulatory mechanisms influencing the establishment of an optimal acidic environment for sperm maturation and storage in the epididymis.

4D Microscopy and Tracking of Chromosomes and the Spindle in C. elegans Early Embryos.

Maintaining genomic integrity throughout successive cell divisions is essential for the proper development and functioning of organisms. Chromosome alignment and segregation occur on a microtubule-based spindle originating from centrosomes. The molecular and cellular mechanisms involved in accurate chromosome segregation during early embryonic divisions are highly conserved between worms and humans. Therefore, C. elegans serves as a robust model for investigating mitotic cell divisions within a metazoan system. Throughout early embryonic development, filming and tracking successive cell divisions becomesprogressively more challenging as the number of cells increases and cell size decreases. To address this challenge, we describe a method for preparing live samples, performing 4D time-lapse imaging, and semi-automated tracking of chromosomes and spindle poles during early mitotic divisions in C. elegans embryos.

CELS-3D-Cutting edge light source for exciting fluorescence in microtome-based 3D microscopy and targeted correlative microscopy.

We discovered that the light entering a triangular ultramicrotome glass knife from the bottom exits the knife through its cutting edge, forming an oblique light sheet illumination suitable for imaging. We adopted this light sheet for side illumination of the sample blocks during sectioning on the ultramicrotome, for 3D imaging, and for targeting fluorescent features for confocal-, electron- and correlative microscopy. In this paper, we present a working prototype named CELS-3D (Cutting Edge Light Source, Three-Dimensional), a microscope mounted on an ultramicrotome. We characterised CELS-3D and applied it for 3D imaging of human liver spheroids with a diameter of approximately 500 μm. The structure of nuclei and tight junctions has been successfully reconstructed over the full spheroid volume. In contrast, a confocal microscope was unable to image spheroids to a depth of greater than 50 μm. CELS-3D shows fluorescence during serial sectioning in an online mode; therefore, it can apply for targeting fluorescence structures for correlative microscopy. We successfully applied CELS-3D for targeted correlative microscopy of human liver spheroids and C. elegans. The CELS-3D can be utilised for less- and non-transparent samples, which encompasses a range of applications, including operation biopsies, experimental organoids/spheroids, artificial cartilage, and bone, among others. The CELS-3D can be effortlessly mounted on the top of any commercially available ultramicrotome, and its operation is straightforward and intuitive.

Morphology of mitochondrial network in disseminated endometriosis cells in spontaneous pneumothorax diagnostic process.

Circulating endometrial cells (CECs) have emerged as a new biomarker of advanced disease in women with endometriosis. The identification of several subtypes of CECs (e.g., stem cell-like, epithelial, glandular, stromal) has opened the way for characterization of endometriosis-associated CECs. This study focused on the isolation and characterization of CECs and disseminated endometrial cells (DECs) in patients with spontaneous pneumothorax (SP). The primary objective was to differentiate between cancer and non-cancer cells in patients with no previous cancer diagnosis. The MetaCell® size-based separation protocol was used to enrich CECs/DECs. Evaluation of the captured cells by 3D microscopy was performed using a NANOLIVE™ microscope using a holographic approach. Based on gene expression analysis (GEA), we can conclude that mitochondria are much more active in primary tumors compared to endometriosis tissue (e.g. MT-ND1, MT-ATP6 genes). The culture of DECs is made of stromal, stem and immune cells. In vitro culture of DECs is characterized by an increase in the epithelial marker KRT18. Similarly, NFE2L2, a proerythroid factor, is also elevated. Further, a significant decrease in the amount of stem and immune cells was observed in the cell culture of DECs. The data presented here show how morphologically plastic the changes in the mitochondrial network can be and how cells can reflect them at the level of gene expression. The markers identified could help in the accompanying diagnostic process of the spontaneous pneumothorax in women of reproductive age.

Cultural exchange and technical artistry: Gold ornaments found in pre-imperial Qin Tomb at Ta’erpo, Shaanxi

The current study investigates the use of precious metals, aesthetic taste, manufacturing techniques, and craftworking practices in the pre-imperial Qin period before the unification of China, focusing on an interdisciplinary study of gold ornaments discovered at the Ta’erpo cemetery in Xianyang, dating to the 4th-3rd centuries BCE. Employing multi-spectral analytical methods, including 3D Digital Microscopy (OM) and Scanning Electron Microscopy with Energy Dispersive X-Ray Spectroscopy (SEM-EDS), we conducted non-invasive analyses and technological study of a selection of gold artefacts. The results reveal the mastery of sophisticated techniques, including granulation and filigree, which were rarely seen in central China prior to the 2nd century BCE. These delicate decorative techniques required precision, skill and deep understanding of gold metalworking, which demonstrated a high level of technological competence among Qin craftsmen. The investigated ornaments were crafted from very pure gold with content reaching up to 99.62 wt% gold, a rarity among early Chinese gold artefacts. Examining pre-imperial Qin goldwork within a broader Eurasian context reveals that these innovative artistic styles and decorative techniques were originally intertwined with wider influences from the Hellenistic world and the central Asian steppes. This research enriches the understanding of ancient civilization's interconnectedness and the ability of local goldsmith to adapt and integrate foreign influences into their own artistic traditions.

(Invited) In Situ Probing of Interfacial Solvation and Electrocatalytic Processes

Electrochemistry inevitably requires the participation of both the electrodes and the electrolytes, with key processes occurring at the electrode-electrolyte interface. While many tools are available to characterize the electrode structures in situ, the interfacial electrolyte species remain hidden from most existing methods. In this talk, I will discuss my lab’s recent efforts on in situ characterization of the liquid structure at electrified interfaces as well as their impacts on electrocatalysis. On the structural side, we use 3D atomic force microscopy to determine the spatial density profile of the interfacial liquid, and identify layered configurations. As to catalytic activities, we use nanoparticle-enhanced Raman spectroscopy to detect the key oxygen reduction reaction intermediates, in addition to the standard electrochemical tests to quantify the electrolyte effects on the reaction kinetics. The combination of multimodal characterization results provides rich insights into the structure-activity relationship.

Surface Wetting Properties of Lithium Anode Characterized Using Laser Scanning Confocal Microscopy

Surface wettability between the lithium metal anode and liquid electrolyte is a critical performance characteristic. Poor wettability can result in nonuniform stripping and deposition of lithium metal, nonuniform SEI formation, formation of dead lithium and; thus, shorter cycle life. Imaging techniques such as laser-induced fluorescence imaging using laser scanning confocal microscopy (LSCM), have become a valuable tool for investigating the surface properties of lithium metal anodes.1 Laser scanning confocal microscopy is an advanced microscopy technique that allows improved depth resolution relative to traditional optical microscopy.Arcadium Lithium Corporation has developed LIOVIX®printable lithium technology, a formulation that can be printed, at industrial speed, on most common substrates, such as Cu foil to produce thin lithium metal foil with thickness in the range of 5 µm to 50 µm with no limitation in width.2 LIOVIX®-based lithium film has a different microstructure when compared to a commercial foil (Figures 1a and 1b). LIOVIX-based thin foil retains rheology modifiers used in the formulation that serve as a 3D skeleton. This unique structure can change lithium metal surface plating behavior. Therefore, the 3D structure might mitigate the growth of dendritic lithium, reduce mechanical degradation, and improve safety and cycle life of the battery.LSCM was used for in-situ, in operando observations of the difference in surface properties and wettability properties of commercial lithium foil and LIOVIX-based lithium foil (Figures 1c and 1d). Lithium metal surface is dynamic and prone to forming various structures and compounds, depending on the conditions it is exposed to. The results showed that LIOVIX-based foil lithium activity is more homogenous and had a shallower interaction when compared to the commercial lithium foil. This potentially signifies more uniformity to the lithium activity in LIOVIX-based foil vs. commercial lithium foil; thus, more uniform surface activity within a battery system.Reference Nishikawa et al., 2010 J. Electrochem. Soc. 157 A1212Yakovleva et al., Battery utilizing printable lithium, U.S. Patent 11, 824, 182, B2, Nov. 21, 2023 Figure 1. Microscope image of A) LIOVIX® -based lithium foil (20um), B) commercial lithium foil (20um); and 3D Confocal microscope images of C) LIOVIX®-based lithium foil (20um) and D) commercial lithium foil (20um). Figure 1

Multiscale Wettability of Microtextured Irregular Surfaces.

Surface microgeometry created by the energy of electric discharges is related to surface wetting behavior. These relationships change depending on the scale of observation. In this work, contact angles correlated with the surface complexity of AA 6060 after electro-discharge machining were analyzed at different observation scales. This research focuses on the methodology of selecting the best scales for observing wetting phenomena on irregular surfaces, as well as indicating the topographic characterization parameters of the surface in relation to the scales. Additionally, the geometric features of the surface that determine the contact angle were identified. In this study, the surfaces of an aluminum alloy are rendered using focus variation 3D microscopy and described by standardized ISO, area-scale, and length-scale parameters. The research also confirms that it is possible to design surface wettability, including its hydrophilicity and hydrophobicity, using electrical discharge machining parameters. The static and dynamic behavior of liquids on surfaces relevant to contact mechanics was also determined.