Μm Depth Research Articles

Fabrication of Through-glass Vias (TGV) based 3D microstructures in glass substrate by a lithography-free process for MEMS applications

Fabrication of Through-glass Vias (TGV) based 3D microstructures in glass substrate by a lithography-free process is presented. Through-holes having an opening size of ∼ 300–500 µm and spiral-shaped embedded redistribution lines of ∼ 290 µm width and ∼ 50 µm depth were directly created in a 400 μm thick glass substrate by the electrochemical discharge machining. A 20 nm thick conformal seed layer was deposited by electroless nickel deposition, which can be a cost-effective alternative to vacuum-based physical vapor deposition techniques. The surface morphology of the electroless layer was characterized using an atomic force microscope and field emission scanning electron microscopy. Scotch-tape test showed a good adhesion of the seed layer with the glass substrate. Copper electrodeposition was performed to increase the thickness, after which thermal annealing was carried out to release the residual stress in the film. The adhesion of electrodeposited copper significantly improved after thermal annealing at 240 °C for 30 min. Electrodeposition is performed again to increase the thickness to the desired level. The current–voltage characterizations show good connectivity, and the average electrical resistance of a 3-turn square-shaped 3D microstructures is 2.41 Ω. Other spirals and square-shaped designs are also fabricated to prove the flexible capability of this ‘lithography-free’ technique.

Experiment investigation on flow boiling heat transfer in a bidirectional counter-flow microchannel heat sink

Improving the critical heat flux (CHF) and avoiding dry out downstream are the keys to enhance the two-phase cooling performance of microchannel heat sinks. In this work, a novel type of bidirectional counter-flow (BCF) microchannels with 600 μm depth and 300μm width, giving a hydraulic diameter of 400μm, is fabricated in an oxygen-free copper base. Flow boiling experiments are conducted in bidirectional counter-flow microchannels and conventional unidirectional parallel-flow (UPF) microchannels, with the deionized water being used as the working fluid. Cases under six mass fluxes ranging from 118 kg/m2·s to 370 kg/m2·s and three inlet subcoolings of 30 ℃, 50 ℃, and 70 ℃ are tested. Two-phase flow behaviors in microchannels are simultaneously captured by a high-speed camera. It is found that, unlike conventional UPF microchannels, the location for the onset of nucleate boiling (ONB) in BCF microchannels is moved from downstream to the middle region. The downstream dry-out, which is usually occurred in UPF microchannels, can be well avoided in BCF microchannels due to the substantial feeding of liquid in adjacent microchannels. The CHF in BCF microchannels can be increased by 33.8∼57.2% compared with the conventional UPF microchannels. Under the combined effect of expanded nucleate boiling region and shortened subcooling region, the average heat transfer coefficient (HTC) in BCF microchannels can be increased by 36.6%∼56.7%. More interestingly, the improvement of heat transfer performance is found to be accompanied by a significant reduction in pressure drop for BCF microchannels in all the experiment cases. In addition, two-phase instabilities in terms of wall temperature and pressure drop oscillations can be significantly suppressed by using BCF microchannels instead of the conventional UPF microchannels. This study proposes a more efficient microchannel heat sink design scheme to deal with the microelectronic cooling challenges.

Label-Free Multiphoton Imaging of Microbes in Root, Mineral, and Soil Matrices with Time-Gated Coherent Raman and Fluorescence Lifetime Imaging.

Imaging biogeochemical interactions in complex microbial systems─such as those at the soil-root interface─is crucial to studies of climate, agriculture, and environmental health but complicated by the three-dimensional (3D) juxtaposition of materials with a wide range of optical properties. We developed a label-free multiphoton nonlinear imaging approach to provide contrast and chemical information for soil microorganisms in roots and minerals with epi-illumination by simultaneously imaging two-photon excitation fluorescence (TPEF), coherent anti-Stokes Raman scattering (CARS), second-harmonic generation (SHG), and sum-frequency mixing (SFM). We used fluorescence lifetime imaging (FLIM) and time gating to correct CARS for the autofluorescence background native to soil particles and fungal hyphae (TG-CARS) using time-correlated single-photon counting (TCSPC). We combined TPEF, TG-CARS, and FLIM to maximize image contrast for live fungi and bacteria in roots and soil matrices without fluorescence labeling. Using this instrument, we imaged symbiotic arbuscular mycorrhizal fungi (AMF) structures within unstained plant roots in 3D to 60 μm depth. High-quality imaging was possible at up to 30 μm depth in a clay particle matrix and at 15 μm in complex soil preparation. TG-CARS allowed us to identify previously unknown lipid droplets in the symbiotic fungus, Serendipita bescii. We also visualized unstained putative bacteria associated with the roots of Brachypodium distachyon in a soil microcosm. Our results show that this multimodal approach holds significant promise for rhizosphere and soil science research.

Deionized Water Electrochemical Machining Hybridized with Alumina Powder Polishing for Microcavity of M-333 Mold Steel

An electrochemical machining (ECM) process for microcavity fabrication with deionized water (DI-water) and an ECM polishing hybrid with alumina powder of 1.0 μm grains on a single micro-EDM machine are proposed. The process adopts tungsten carbide as tool electrode and M-333 tool steel as the mold material. It reveals that employing the 30 μm/min feed rate with 50 mA and 0.2 ms of pulse-width is suitable for DI-water electrochemical machining. The DI-water ECM process can achieve an excellent surface roughness at Ra 0.169 µm on a semispherical round cavity. Combining the ECM with hybrid polishing with the alumina powder can achieve a better profile for a much deeper cavity than pure electrolytic discharge machining. The hybrid ECM polishing can efficiently finish a micro square insert of 0.6 mm length at 64 μm depth. Such ECM milling can achieve an S-shaped microchannel of radius 1.0 mm and a slot of 1.0 × 0.5 mm2 with 110 μm depth, demonstrating its feasibility and the surface integrity with accurate profile and roughness of Ra 0.227 μm. This study provides a cost-effective scheme for micro mold fabrication with a conventional micro-EDM machine tool and an intuitive and convenient optional process. However, some micro-electrical discharges occurred due to the breakdown of insulation, which creates micro craters on the surface of the parts.

Sub-surface microstructural investigation for establishing micro-mechanisms of wear in sliding of SiC and SiC-WC ceramics

Dual-beam FIB/FEG-SEM and TEM/HRTEM observations of sub-surfaces of SiC and SiC-50 wt% WC composite disks worn against SiC ball have provided important insights into the micro-mechanisms of material removal and the role of WC towards suppressing the same. Sub-surface analysis reveals the silicon oxide rich tribochemical layer just underneath the worn surfaces of monolithic SiC. Further below this tribochemical layer, dislocations and twins in SiC grains, as well as micro-cracks, are identified. Micro-cracks get extended up to ∼2 μm depth below the layer, eventually leading to material removal in SiC ceramics. In case of the SiC-WC composite, neither is the tribochemical layer dominant, nor is twin/dislocation networks seen to extend beyond the SiC/WC interfaces. Overall, the present study highlights that WC particulate reinforcements in SiC-WC composite minimize the wear damage by suppressing oxidative wear and restricting the generation of micro-cracks, which otherwise form extensively due to stress build-up at the tips of dislocations or twins in SiC grains.

Microstructure in subsurface and fatigue properties of shot peened maraging steel

Rotating bending fatigue tests were carried out to investigate the effect of microstructure in subsurface on the fatigue properties of a shot peened maraging steel. The steel had a fine-grained microstructure formed at the surface layer with 50-70 μm in depth. Especially a thin surface layer showed a nano-size structure. A surface fracture occurred at high stress levels, while the combined fracture occurred due to coalescence of a surface crack and an internal one initiated independently with decreasing in stress level until 108 cycles. In all of the macroscopic fracture surfaces in the shot-peened specimen, a ring-shaped flat area was observed at the surface layer irrespective of the fracture mode and the depth of the area nearly corresponded to the one of the fine-grained microstructure. The formation mechanism of the ring-shaped area was explained from the initiation and propagation properties of a surface crack in the surface layer in connection with the microstructure.

Interface performance of Bi<sub>2</sub>Te<sub>3</sub>-based micro thermoelectric devices optimized synergistically by surface modification engineering

The miniaturization of thermoelectric devices raises a strong requirement for the excellent interfacial properties of thermoelectric elements. Thus, achieving a heterogeneous interface with low interfacial contact resistivity and high interfacial bonding strength is a prerequisite for the successful fabrication of high-performance and high-reliability Bi<sub>2</sub>Te<sub>3</sub>-based micro thermoelectric devices. In this work, we adopt the acid pickling method to modify the surface structure of Bi<sub>0.4</sub>Sb<sub>1.6</sub>Te<sub>3</sub> material to synergistically optimize the interfacial properties of Bi<sub>0.4</sub>Sb<sub>1.6</sub>Te<sub>3</sub>/Ni thermoelectric elements. The acid pickling process effectively modulates the work function of Bi<sub>0.4</sub>Sb<sub>1.6</sub>Te<sub>3</sub> material, which dramatically reduces the contact barrier height of Ni/Bi<sub>0.4</sub>Sb<sub>1.6</sub>Te<sub>3</sub> heterojunction from 0.22 to 0.02 eV. As a consequence, the corresponding interfacial contact resistivity of the element is greatly reduced from 14.2 to 0.22 μΩ·cm<sup>2</sup>. Moreover, the acid pickling process effectively adjusts the surface roughness of the matrix, forming a V-shaped pit of 2–5 μm in depth on the substrate surface and leading to a pinning effect. This significantly enhances the physical bonding between the material surface and the Ni layer, which, together with the metallurgical bond formed by the interfacial diffusion reaction zone of about 50-nm-thick Ni/Bi<sub>0.4</sub>Sb<sub>1.6</sub>Te<sub>3</sub>, greatly enhances the interfacial bond strength from 7.14 to 22.34 MPa. The excellent interfacial properties are further validated by the micro-thermoelectric devices. The maximum cooling temperature difference of 4.7 mm× 4.9 mm micro thermoelectric device fabricated by this process achieves 56.5 K, with hot side temperature setting at 300 K, and the maximum output power reaches 882 μW under the temperature gradient of 10 K. This work provides a new strategy for realizing the synergetic optimization of interfacial properties and opens up a new avenue for improving the performance of micro thermoelectric devices.

Metal-stimulated decomposition of sapphire surface in flux electrons with an energy of 70 keV

Abstract: Metal-stimulated decomposition of sapphire surface at room temperature in a flux of electrons with energy of 70 keV. The stimulant used is an ensemble of crystalline islands of gold. It was first established that the presence of an ensemble of gold islands on the surface of sapphire significantly reduces substrate temperature and electron energy at which decomposition occurs surfaces. Etching pits form near gold islands and have an elongated shape with the following dimensions: length up to 1.2 μm, width up to 0.8 μm and average depth 20 nm. Maximum area the base of the islands increases from 0.6 to 1.8 μm2. Keywords: sapphire, gold, metal-stimulated decomposition, electron flux.

Fabrication of Precise Hemispherical End Tool for Micro Incremental Sheet Forming using Reverse-µEDM

The present work aims at the feasibility test for producing Micro incremental sheet forming (µISF) tool by Reverse micro electro-discharge machining (Reverse-µEDM) process. A pre-fabricated dimple-shaped microcavity on the tool plate is used for fabricating a hemispherical end tool. The dimple of 600 µm diameter and 300 µm depth is considered to produce the hemispherical end tool in the range of radius 300-400 µm. A parametric study has been performed to examine their effect on the dimensional accuracy and surface quality of the fabricated tool. For machining tungsten carbide as workpiece and titanium as reference tool plate material in Reverse-µEDM, three different input parametric settings, viz., low, moderate, and high, are chosen. The Reverse-µEDM developed µISF micro tools at each setting have been characterized and compared for MRR, tool wear, surface roughness, and dimensional accuracy. The tool-tip obtained with a low set of parameters showed better results than the other two parametric arrangements.

Analysis of microhardness and degree of work hardening (DWH) while turning Inconel 718 with high pressure coolant environment

Inconel is considered as one the difficult to cut metal and to find out causes of why Inconel 718 is difficult to machine is a topic of research for many researcher since past many years. The availability of high-pressure cooling (HPC) of cutting tools can be very effective when machining the difficult to cut metal like Inconel 718. With high-pressure coolant, it is possible to improve machinability of Inconel 718. Analysis of Microhardness and Degree of Work Hardening (DWH) is presented in this paper while Turning Inconel 718 with High Pressure Coolant Environment. There is a sudden change in micro hardness values in region between 30 and 120 μm depths from the machined surface. After this depth the microhardness of the machine affected zone slowly approaches the bulk microhardness. The bulk microhardness is found at a depth of about 270–300 μm below the machined surface for all samples. The microhardness close to the machined surface is found in the order of 1.11 times the bulk microhardness.

1-(4-Hydroxyphenyl)-2H-tetrazole-5-thione as a leveler for acid copper electroplating of microvia.

Microvia filling by copper electroplating was performed using plating solution with 1-(4-hydroxyphenyl)-2H-tetrazole-5-thione (HPTT) as the leveler. Galvanostatic Measurements (GMs), Linear Sweep Voltammetry (LSV) and Electrochemical Impedance Spectroscopy (EIS) tests were carried out to investigate the electrochemical behaviors of HPTT and its synergistic effect with other additives, in comparison with 1-phenyltetrazole-5-thione (PMT). GMs showed a convection-dependent interaction between PEP and HPTT. LSV and EIS tests indicated both HPTT and PMT enhanced the inhibition effect of PEP, and the synergistic effect of HPTT and PEP was stronger than that of PMT. Cross-section images illustrated the filling rate of the microvia with a 150 μm diameter and a 75 μm depth was 95.6% in 60 minutes with HPTT as the leveler. Frontier Molecular Orbitals (FMO) and Electrostatic Potential (ESP) of HPTT and PMT using quantum chemical calculations predicted the reaction sites for electrophilic and nucleophilic attack. Quantum chemical calculations suggested that HPTT is easier than PMT to bond to a copper surface and PEP.

Engineering of Tracheal Grafts Based on Recellularization of Laser-Engraved Human Airway Cartilage Substrates.

ObjectiveImplantation of tissue-engineered tracheal grafts represents a visionary strategy for the reconstruction of tracheal wall defects after resections and may develop into a last chance for a number of patients with severe cicatricial stenosis. The use of a decellularized tracheal substrate would offer an ideally stiff graft, but the matrix density would challenge efficient remodeling into a living cartilage. In this study, we hypothesized that the pores of decellularized laser-perforated tracheal cartilage (LPTC) tissues can be colonized by adult nasal chondrocytes (NCs) to produce new cartilage tissue suitable for the repair of tracheal defects.DesignHuman, native tracheal specimens, isolated from cadaveric donors, were exposed to decellularized and laser engraving–controlled superficial perforation (300 μm depth). Human or rabbit NCs were cultured on the LPTCs for 1 week. The resulting revitalized tissues were implanted ectopically in nude mice or orthotopically in tracheal wall defects in rabbits. Tissues were assayed histologically and by microtomography analyses before and after implantation.ResultsNCs were able to efficiently colonize the pores of the LPTCs. The extent of colonization (i.e., percentage of viable cells spanning >300 μm of tissue depth), cell morphology, and cartilage matrix deposition improved once the revitalized constructs were implanted ectopically in nude mice. LPTCs could be successfully grafted onto the tracheal wall of rabbits without any evidence of dislocation or tracheal stenosis, 8 weeks after implantation. Rabbit NCs, within the LPTCs, actively produced new cartilage matrix.ConclusionImplantation of NC-revitalized LPTCs represents a feasible strategy for the repair of tracheal wall defects.

Modification of the Structural, Microstructural, and Elastoplastic Properties of Aluminum Wires after Operation

The health of the components that make up the cables of power lines, and hence their service life, is governed at the micro level by changes in their structure and microstructure. In this paper, the structure and microstructure of aluminum wires of overhead power transmission lines (without a steel core) of different service life from 0 to 62 years have been investigated by quantitative techniques of X-ray diffraction, diffraction of back-scattered electrons, and the densitometric method. Elastoplastic properties of the wires have been tested by the acoustic-resonance method. A decrease in the Al material density Δρ/ρ∼−0.165% was found in the near-surface layer of ∼36 μm depth and in the bulk of the wires with an increase in the service life from 0 to 18 years. The density decrease is associated with the accumulation of microcracks. The following density increase (Δρ/ρ∼−0.06%) in wires with a service life of 62 years is attributed to the formation of ∼0.7 vol.% of crystalline Al oxides in the near-surface layers of the wires. The nature of the change in the elastic modulus, microplastic flow stress, and decrement indicates complex structural changes correlating with the results obtained by diffraction methods.

How Does a Cell Change Flow Direction Due to a Micro Groove?

The change in direction of a cell flowing over an oblique micro groove has been analyzed in vitro. The micro flow-channel (0.05 mm height x 1 mm width x 25 mm length) with oblique micro grooves (4.5 μm depth) was manufactured on a polydimethylsiloxane (PDMS) disk by the micromachining technique. The angle between the main flow direction and the longitudinal axis of the groove is 45 degrees. The effect of variation of the groove width (0.03 mm, 0.04 mm, and 0.05 mm) was studied. Myoblasts (C2C12: mouse myoblast cell line) were used in the test. The main flow velocity (0.02 mm/s < vx < 0.23 mm/s) of the medium was controlled by the pressure difference between the inlet and the outlet. The shape of each flowing cell was tracked on a movie recorded by the camera attached to the eyepiece of the microscope. The experimental results show that the change of the direction of each cell by each groove depends on the shape of the cell, which depends on both the shape of the cell and the width of the groove.

Response of silicon nitride ceramics subject to laser shock treatment

A comprehensive and novel investigation on multiple-layer, square-beam laser shock treatment (“laser peening”) of Si 3 N 4 ceramics is reported in this work. Surface topography, hardness, fracture toughness (K Ic ), residual stresses, and microstructural changes were investigated. The evaluation of fracture toughness via the Vickers hardness indentation method revealed a reduction in crack lengths produced by the indenter after laser shock treatment (LST). Upon appropriate calculation, this revealed an increase in K IC of 60%. This being attributed to a near-surface (50 μm depth) compressive residual stress measured at −289 MPa. Multiple layer LST also induced beneficial residual stresses to a maximum measured depth of 512 μm. Oxidation was evident, only on the top surface of the ceramic, post LST (<5 μm depth) and was postulated to be due to hydrolyzation . The surface enhancement in K IC and flaw-size reduction was assigned to an elemental change on the surface, whereby, Si 3 N 4 was transformed to SiO 2 , particularly, with multiple layers of LST. Compressive residual stresses measured in the sub-surface were attributed to mechanical effects (below sub-surface elastic constraint) and corresponding shock-wave response of the Si 3 N 4 . This work has led to a new mechanistic understanding regarding the response of Si 3 N 4 ceramics subject to the LST deployed in this resesrch. The findings are significant because inducing deep compressive residual stresses and corresponding enhancement in surface K IC are important for the enhanced durability in many applications of this ceramic, including cutting tools, hip and knee implants, dental replacements, bullet-proof vests and rocket nozzles in automotive, aerospace, space and biomedical industries.

Novel boriding technique of low-carbon steel weldments

Boriding is considered one of the essential surface treatments for carbon steels during the last decades. The conventional methods of boriding are subjected to many limitations due to the sophisticated setup and the time-consuming treatment. Therefore, less complex methods and less time consumption are the main research objectives past couple of years. This research suggests an enhanced boriding surface treatment technique for low carbon steel. The advantages of the proposed method include the reduction of boriding process time through the development of new boron rich compounds which consequently eliminates the need of specially designed furnaces. The illustrated outputs reveal promising results without sacrificing the physical properties. The proposed technique was carried out experimentally. Depth of penetration and microhardness were measured and compared with results from previous literature. Some trials have shown 35 µm depth of penetration of boron layer at 30 min treatment time associated with micro-hardness up to 2388 HV.

Novel nanostructured resin infiltrant containing calcium phosphate nanoparticles to prevent enamel white spot lesions

ObjectivesThe objective of this study was to develop a novel nanostructured resin infiltrant containing nanoparticles of amorphous calcium phosphate (NACP) to treat enamel white spot lesions (WSLs). Physical properties and the therapeutic effect of the new resin infiltrant were investigated for the first time. MethodsNACP was incorporated into ICON (Icon caries infiltrant, DMG, Germany) with different mass fractions. Cytotoxicity, degree of conversion, surface hardness, calcium (Ca) and phosphorus (P) ions release concentrations were tested. After application to the demineralized enamel samples, the color changes were determined. Surface and cross-sectional hardness were measured, scanning electron microscopy (SEM) images were taken on the cross-section of samples to observe microstructure changes after 14-day pH cycling. ResultsIncorporating 10%–30% of NACP did not compromise the biocompatibility and physical properties of the resin infiltrant. ICON + 30% NACP group had long-lasting and high level of Ca and P ion release. After 14-day pH cycling, enamel surface hardness of ICON + 30% NACP group was 1.83 ± 0.21 GPa, significantly higher than the control group (1.32 ± 0.18 GPa) (p < 0.05). ICON + 30NACP group had the highest cross-sectional enamel hardness among all groups (p < 0.05), especially at 50 μm and 100 μm depth. SEM images showed that apparent enamel prism and inter-prism gaps in negative control were masked by mineral deposition in ICON + 30% NACP group. SignificanceThe novel ICON+30% NACP infiltrant is promising to inhibit enamel WSLs, protect the enamel and increase its hardness.

Visual Outcomes After Implantation of Allogenic Lenticule in a 100-µm Pocket for Moderate to High Hyperopia: 2-Year Results.

To investigate 2-year visual outcomes, stability, and predictability after allogenic lenticule implantation in a 100-µm pocket for moderate to high hyperopia correction. In this prospective case series, 14 eyes of 9 patients with moderate to high hyperopia ranging from +3.00 to +8.00 diopters sphere were included between March and September 2018. Allogenic lenticules extracted from myopic small incision lenticule extraction were implanted into a pocket created by femtosecond laser at a 100-µm depth in recipients with hyperopia. All patients were followed up for 2 years. Uncorrected (UDVA) and corrected (CDVA) distance visual acuity, manifest refraction, corneal topography, Fourier-domain optical coherence tomography, and in vivo confocal microscopy were examined. At postoperative 2 years, 2 eyes (14.3%) gained one line of CDVA, 11 eyes (78.6%) had unchanged CDVA, and 1 eye (7.1%) lost one line of CDVA. No eyes lost two or more lines of CDVA. Twelve of the treated eyes (85.7%) had postoperative uncorrected near visual acuity equal to or better than pre-operative values. The spherical equivalent decreased from +5.53 ± 1.45 D preoperatively to -0.60 ± 1.20 D at postoperative year 2 (P < .001). The anterior mean keratometric readings increased from 42.41 ± 1.03 D preoperatively to 48.38 ± 1.98 D at postoperative year 2 (P < .001). Of 14 treated eyes, 10 eyes (71.4%) had spherical equivalent within ±1.00 D. The findings suggest that allogenic lenticule transplantation may be a promising option for the correction of moderate to high hyperopia. [J Refract Surg. 2021;37(11):734-740.].

Experimental investigation on flow boiling heat transfer of R134a in a minichannel heatsink with copper foam fins

Metal foam is widely used for heat-transfer enhancement. Flow boiling of R134a in a minichannel heatsink with copper foam fins was studied. The heat sink contained four channels that were 503 μm in width and 990 μm in depth, and the copper foam fins had a porosity of 0.8. The mass flux in the experiment ranged from 595 to 1213 kg/m2 s, and the heat flux was in the range of 22–172 W/cm2. Heat transfer coefficients under different mass flow rates, heat fluxes, and qualities were obtained. The heat transfer deterioration phenomenon at different heat fluxes was analyzed. Compared with a solid-fin minichannel heat sink, the heat transfer was enhanced at low heat fluxes, whereas it was weakened at high heat fluxes. The turning point heat flux was between 87 and 100 W/cm2 and increased as the flow rate increased. Mechanisms of the heat transfer deterioration in the copper foam minichannel heatsink were explained by comparing flow patterns in the two heatsinks at the high heat flux.

Use of Pulsed RF Glow Discharge Optical Emission Spectroscopy for the Study of Elemental Distribution of Li-NMC Cathode at Various State of Charge in Li-Ion Batteries

Glow discharge optical emission spectroscopy (GDOES) is an analytical technique that provides both a surface and depth profile of the elemental composition and distribution of solid or porous samples. Although GDOES is a destructive technique, it provides the advantage of being a high throughput technique that is highly sensitive to all elements from H to U and can provide high resolution (from nm to µm) depth profiles of elemental distributions in practically any sample. Previous works have investigated and optimized the operating parameters of using GDOES to study negative electrode materials and from the data gathered therein [1] we used 5% H2 in Ar gas in this study to increase sputtering rate of Li-NMC cathode materials and to increase sensitivity to Li in the sample to provide a more detailed elemental distribution. This study investigates the use of GDOES as a method for analyzing elemental and specifically lithium distribution in Li-NMC cathode materials in extreme depth and with validation from other techniques such as x-ray photoelectron spectroscopy (XPS) and x-ray fluorescence (XRF) and with additional morphological analysis of cells using x-ray computed tomography (X-ray CT).In this study coin cells were assembled in an Ar filled glovebox using a 15 mm diameter double sided graphite anode coated on a Cu current collector, 14 mm double sided NMC 111 cathode coated on an Al current collector, either a Celgard 3401 or 5550 separator, and 75 µL of 1M LiPF6–EC:EMC (3:7) electrolyte. The coin cells were then brought outside and EIS data was taken on the freshly made cells. They were then allowed to rest for 12 hours before going through a formation cycle at a C-rate of C/20. After the formation cycle, all cells went through 10 charge/discharge cycles at a C-rate of C/5. After these cycles EIS data was taken again and the cells were then charged to different states of charge (SOC) of 0, 25, 75, and 100% and again EIS data was taken after this. The cells were then brought back into the glovebox where they were de-crimped and disassembled. The electrodes were then rinsed in DMC and dried. They were then analyzed using XPS for surface analysis, XRF for elemental mapping, and X-ray CT for analysis of electrode morphology. Finally, they were analyzed using GDOES and the through thickness Li atomic distribution was plotted for the SOCs listed. An example of atomic concentration distribution of various elements for a SOC of 0% is shown by Figure 1. This study aims to validate the use of GDOES to generate accurate Li distribution profiles and elemental distributions in Li-NMC cathode materials.[1] H. Takahara, A. Kojyo, K. Kodama, T. Nakamura, K. Shono, Y. Kobayashi, M. Shikano, and H. Kobayashi, J. Anal. At. Spectrom., 29, 95–104 (2014). Figure 1