Implantable microelectrode arrays are an effective method for understanding neurotransmitter dynamics with high spatial resolution. In particular, carbon-based electrodes are efficient for electrochemical detection of dopamine, a neurotransmitter studied for its role in motor movement and reward-seeking behavior. However, very few options exist for arrayed carbon microelectrodes, specifically on flexible polymeric probes. We demonstrate fabrication of polyimide probes featuring single walled carbon nanotube (SWCNT) microelectrode arrays and characterize their dopamine detection performance. First, SWCNT synthesis parameters were optimized to grow high density SWCNT “forests” that have uniform height with electrode diameters ranging from 15 μm to 100 μm, as these dimensions are spatially relevant to chemical sensing in an animal model. These SWCNT microelectrodes were then incorporated into a microfabrication process involving deposition and patterning of polyimide substrate and metal traces. The process flow was designed such that the polyimide was not exposed to the high temperatures required to grow SWCNTs. Instead, a bottom-up approach was utilized, in which the SWCNT catalyst was first patterned, the SWCNTs were synthesized on a silicon substrate, then polyimide and trace metal layers were deposited and patterned. Prototype probes were fabricated containing the same range of electrode diameters as those used for SWCNT synthesis development to determine the effect of electrode diameter on ease of microfabrication. Microelectrodes ranging from 15 μm to 50 μm in diameter were found to release from the carrier wafer more easily, while larger electrodes demonstrated poor release. These probes demonstrate a concentration-dependent response to dopamine, with high sensitivity compared to microelectrode arrays consisting of bare metal. Further development of this electrode material will enable neuroscientists to study dopamine at higher spatial resolution, with the benefit of utilizing flexible probes.
{"title":"Synthesis and Fabrication of Single Walled Carbon Nanotube Microelectrode Arrays on Flexible Probes for Neurotransmitter Detection","authors":"Sei Jin Park, Anna N. Ivanovskaya, A. Yorita","doi":"10.1115/msec2022-85273","DOIUrl":"https://doi.org/10.1115/msec2022-85273","url":null,"abstract":"\u0000 Implantable microelectrode arrays are an effective method for understanding neurotransmitter dynamics with high spatial resolution. In particular, carbon-based electrodes are efficient for electrochemical detection of dopamine, a neurotransmitter studied for its role in motor movement and reward-seeking behavior. However, very few options exist for arrayed carbon microelectrodes, specifically on flexible polymeric probes. We demonstrate fabrication of polyimide probes featuring single walled carbon nanotube (SWCNT) microelectrode arrays and characterize their dopamine detection performance. First, SWCNT synthesis parameters were optimized to grow high density SWCNT “forests” that have uniform height with electrode diameters ranging from 15 μm to 100 μm, as these dimensions are spatially relevant to chemical sensing in an animal model. These SWCNT microelectrodes were then incorporated into a microfabrication process involving deposition and patterning of polyimide substrate and metal traces. The process flow was designed such that the polyimide was not exposed to the high temperatures required to grow SWCNTs. Instead, a bottom-up approach was utilized, in which the SWCNT catalyst was first patterned, the SWCNTs were synthesized on a silicon substrate, then polyimide and trace metal layers were deposited and patterned. Prototype probes were fabricated containing the same range of electrode diameters as those used for SWCNT synthesis development to determine the effect of electrode diameter on ease of microfabrication. Microelectrodes ranging from 15 μm to 50 μm in diameter were found to release from the carrier wafer more easily, while larger electrodes demonstrated poor release. These probes demonstrate a concentration-dependent response to dopamine, with high sensitivity compared to microelectrode arrays consisting of bare metal. Further development of this electrode material will enable neuroscientists to study dopamine at higher spatial resolution, with the benefit of utilizing flexible probes.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79873356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ceramic binder jetting processes have inherent limitations in achieving high density due to the low packing density of the powder bed. An emerging route to mitigate the low packing density in ceramic binder jetting entails uniaxial compaction of newly spread powder layers prior to ink deposition. The introduction of layerwise pressure induced a stress shielding effect, i.e., unbalanced stresses between the printed region saturated with ink and the surrounding loose powder, which generates heterogeneous stress in the powder bed and ultimately influences the density of the final part. In this paper, we attempt to better understand the stress shielding effect during the compaction of a selectively ink-jetted powder bed as a function of the printing pattern, i.e., ratio of printed to unprinted sector. Our findings reveal a decreased print area increased the resulting stress shielding effect. Additionally, when pressed without neighboring dry powder, a printed region experienced a much higher stress than the hybrid composition. The dry powder experienced the opposite effect, where when pressed alone, the dry powder had a much lower stress than when pressed with saturated powder. Findings will assist in density prediction and print pattern determination of compacted binder jetted ceramics.
{"title":"Characterization of Stress Shielding in Pressure-Assisted Ceramic Binder Jetting","authors":"L. Kirby, F. Fei, Xuan Song","doi":"10.1115/msec2022-85766","DOIUrl":"https://doi.org/10.1115/msec2022-85766","url":null,"abstract":"\u0000 Ceramic binder jetting processes have inherent limitations in achieving high density due to the low packing density of the powder bed. An emerging route to mitigate the low packing density in ceramic binder jetting entails uniaxial compaction of newly spread powder layers prior to ink deposition. The introduction of layerwise pressure induced a stress shielding effect, i.e., unbalanced stresses between the printed region saturated with ink and the surrounding loose powder, which generates heterogeneous stress in the powder bed and ultimately influences the density of the final part. In this paper, we attempt to better understand the stress shielding effect during the compaction of a selectively ink-jetted powder bed as a function of the printing pattern, i.e., ratio of printed to unprinted sector. Our findings reveal a decreased print area increased the resulting stress shielding effect. Additionally, when pressed without neighboring dry powder, a printed region experienced a much higher stress than the hybrid composition. The dry powder experienced the opposite effect, where when pressed alone, the dry powder had a much lower stress than when pressed with saturated powder. Findings will assist in density prediction and print pattern determination of compacted binder jetted ceramics.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80005189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xinyao Zhang, Kareem A. Eltouny, Xiao Liang, S. Behdad
Disassembly is an essential process for the recovery of end-of-life (EOL) electronics in remanufacturing sites. Nevertheless, the process remains labor-intensive due to EOL electronics’ high degree of uncertainty and complexity. The robotic technology can assist in improving disassembly efficiency, however, the characteristics of EOL electronics pose difficulties for robot operation, such as removing small components. For such tasks, detecting small objects is critical for robotic disassembly systems. Screws are widely used as fasteners in ordinary electronic products while having small sizes and varying shapes in a scene. To achieve robotic disassembly of screws, the location information and the required tools need to be predicted. This paper proposes a framework to automatically detect screws and recommend related tools for disassembly. First, the YOLOv4 algorithm is used to detect screw targets in EOL electronic devices, and then a screw image extraction mechanism is executed based on the position coordinates predicted by YOLOv4. Second, after obtaining the screw images, the EfficientNetv2 algorithm is applied for screw shape classification. In addition to proposing a framework for automatic small-object detection, we explore how to modify the object detection algorithm to improve its performance and discuss the sensitivity of tool recommendations to the detection predictions. A case study of three different types of screws is used to evaluate the performance of the proposed framework.
{"title":"Automatic Screw Detection and Tool Recommendation System for Robotic Disassembly","authors":"Xinyao Zhang, Kareem A. Eltouny, Xiao Liang, S. Behdad","doi":"10.1115/msec2022-85403","DOIUrl":"https://doi.org/10.1115/msec2022-85403","url":null,"abstract":"\u0000 Disassembly is an essential process for the recovery of end-of-life (EOL) electronics in remanufacturing sites. Nevertheless, the process remains labor-intensive due to EOL electronics’ high degree of uncertainty and complexity. The robotic technology can assist in improving disassembly efficiency, however, the characteristics of EOL electronics pose difficulties for robot operation, such as removing small components. For such tasks, detecting small objects is critical for robotic disassembly systems. Screws are widely used as fasteners in ordinary electronic products while having small sizes and varying shapes in a scene. To achieve robotic disassembly of screws, the location information and the required tools need to be predicted. This paper proposes a framework to automatically detect screws and recommend related tools for disassembly. First, the YOLOv4 algorithm is used to detect screw targets in EOL electronic devices, and then a screw image extraction mechanism is executed based on the position coordinates predicted by YOLOv4. Second, after obtaining the screw images, the EfficientNetv2 algorithm is applied for screw shape classification. In addition to proposing a framework for automatic small-object detection, we explore how to modify the object detection algorithm to improve its performance and discuss the sensitivity of tool recommendations to the detection predictions. A case study of three different types of screws is used to evaluate the performance of the proposed framework.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86467912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper introduces an imaging technique to enhance three-dimensional (3D) surface profiling of the machined part by using a feature-selective segmentation (FSS) and merging technique. Spatially-resolved 3D stereoscopic images were achieved compared with those of the conventional filtering-based imaging process. Two identical vision cameras simultaneously take images of the parts at different angles, and 3D images can be reconstructed by stereoscopy algorithm. High-pass and low-pass filtering of the images involves data loss and lowers the spatial resolution of the image. In this study, the 3D reconstructed image resolution was significantly improved by automatically classifying and selectively segmenting the features on the 2D images, locally and adaptively applying super-resolution algorithm to the segmented images based on the classified features, and then merging those filtered segments. Here, the features are transformed into masks that selectively separate the features and background images for segmentation. The measurement system scanned the machined part with various shape and height information. The experimental results were compared with those of a conventional high-pass and low-pass filtering method in terms of spatial frequency and profile accuracy. As a result, the selective feature segmentation technique was capable of spatially-resolved 3D stereoscopic imaging while preserving imaging features. The proposed imaging method will be implemented with strobo-stereoscopy for in-process 3D surface imaging.
{"title":"Enhanced Three-Dimensional Surface Profiling Technique Based on a Feature-Selective Segmentation and Merging","authors":"Xiangyu Guo, Chabum Lee","doi":"10.1115/msec2022-85343","DOIUrl":"https://doi.org/10.1115/msec2022-85343","url":null,"abstract":"\u0000 This paper introduces an imaging technique to enhance three-dimensional (3D) surface profiling of the machined part by using a feature-selective segmentation (FSS) and merging technique. Spatially-resolved 3D stereoscopic images were achieved compared with those of the conventional filtering-based imaging process. Two identical vision cameras simultaneously take images of the parts at different angles, and 3D images can be reconstructed by stereoscopy algorithm. High-pass and low-pass filtering of the images involves data loss and lowers the spatial resolution of the image. In this study, the 3D reconstructed image resolution was significantly improved by automatically classifying and selectively segmenting the features on the 2D images, locally and adaptively applying super-resolution algorithm to the segmented images based on the classified features, and then merging those filtered segments. Here, the features are transformed into masks that selectively separate the features and background images for segmentation. The measurement system scanned the machined part with various shape and height information. The experimental results were compared with those of a conventional high-pass and low-pass filtering method in terms of spatial frequency and profile accuracy. As a result, the selective feature segmentation technique was capable of spatially-resolved 3D stereoscopic imaging while preserving imaging features. The proposed imaging method will be implemented with strobo-stereoscopy for in-process 3D surface imaging.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82400487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Paavana Krishna Mandava, R. Joyce, James B. Day, Roozbeh Salary
The goal of this research work is to fabricate mechanically robust, porous, and biocompatible bone scaffolds with textured surfaces (for cell/tissue adhesion) for the treatment of osseous fractures. The objective of the work is to investigate the mechanical properties of triply periodic minimal surface (TPMS) bone scaffolds, fabricated using fused deposition modeling (FDM) additive manufacturing process, based on a medical grade composite composed of polyamide, polyolefin, and cellulose fibers. FDM has emerged as a high-resolution method for the fabrication of biological tissues and constructs. FDM allows for non-contact, multi-material deposition of functional materials for tissue engineering applications. However, the FDM process is intrinsically complex; the complexity of the process, largely, stems from complex physical phenomena and material-process interactions, which may adversely influence the mechanical properties, the surface morphology, and ultimately the functional characteristics of fabricated bone scaffolds. Consequently, physics-based material and process characterization would be an inevitable need. In this study, seven TPMS bone scaffolds were fabricated, based on the medical-grade polymer composite. The compression properties of the fabricated bone scaffolds were measured using a compression testing machine. The outcomes of this study pave the way for the fabrication of complex composite bone scaffolds with tunable medical and functional properties.
{"title":"Investigation of the Mechanical Properties of Additively Manufactured Bone Tissue Scaffolds, Composed of Polyamide, Polyolefin, and Cellulose Fibers","authors":"Paavana Krishna Mandava, R. Joyce, James B. Day, Roozbeh Salary","doi":"10.1115/msec2022-85435","DOIUrl":"https://doi.org/10.1115/msec2022-85435","url":null,"abstract":"\u0000 The goal of this research work is to fabricate mechanically robust, porous, and biocompatible bone scaffolds with textured surfaces (for cell/tissue adhesion) for the treatment of osseous fractures. The objective of the work is to investigate the mechanical properties of triply periodic minimal surface (TPMS) bone scaffolds, fabricated using fused deposition modeling (FDM) additive manufacturing process, based on a medical grade composite composed of polyamide, polyolefin, and cellulose fibers. FDM has emerged as a high-resolution method for the fabrication of biological tissues and constructs. FDM allows for non-contact, multi-material deposition of functional materials for tissue engineering applications. However, the FDM process is intrinsically complex; the complexity of the process, largely, stems from complex physical phenomena and material-process interactions, which may adversely influence the mechanical properties, the surface morphology, and ultimately the functional characteristics of fabricated bone scaffolds. Consequently, physics-based material and process characterization would be an inevitable need. In this study, seven TPMS bone scaffolds were fabricated, based on the medical-grade polymer composite. The compression properties of the fabricated bone scaffolds were measured using a compression testing machine. The outcomes of this study pave the way for the fabrication of complex composite bone scaffolds with tunable medical and functional properties.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83495732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Understanding heat generation can help improve one’s surgical drilling skill to avoid thermal injury. Surgical drilling is mostly done manually, so it can be time-consuming to create personalized thermal models to assess each drilling. For this reason, this paper presents a framework for 2D real-time heat map generation for a moving, varying heat source problem based on neural networks (NN) and linear time-invariant system (LTI). In this framework, several location-specific heat maps and their temporal responses are calculated by finite element analysis (FEA) and trained through NN to build a surrogate model. The total heat map of any given moving heat source can be generated by the superposition of a series of location-specific heat maps along the moving path. The NN training shows a correlation over 99%, indicating a highly representative surrogate model. The validation study of comparing two FEA-based moving heat source problems with the framework predicted results show overall good agreement. Error sources and improvement methods are discussed in this paper.
{"title":"A Neural Network-Based Framework of Real-Time Heat Map Generation for Surgical Hand-Held Drilling","authors":"Pei-Ching Kung, M. Heydari, Bruce L. Tai","doi":"10.1115/msec2022-85693","DOIUrl":"https://doi.org/10.1115/msec2022-85693","url":null,"abstract":"\u0000 Understanding heat generation can help improve one’s surgical drilling skill to avoid thermal injury. Surgical drilling is mostly done manually, so it can be time-consuming to create personalized thermal models to assess each drilling. For this reason, this paper presents a framework for 2D real-time heat map generation for a moving, varying heat source problem based on neural networks (NN) and linear time-invariant system (LTI). In this framework, several location-specific heat maps and their temporal responses are calculated by finite element analysis (FEA) and trained through NN to build a surrogate model. The total heat map of any given moving heat source can be generated by the superposition of a series of location-specific heat maps along the moving path. The NN training shows a correlation over 99%, indicating a highly representative surrogate model. The validation study of comparing two FEA-based moving heat source problems with the framework predicted results show overall good agreement. Error sources and improvement methods are discussed in this paper.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75103901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Promising developments have shown the untapped potential of additive manufacturing (AM) for fabricating molded fiber molds (MFM), a critical piece for the molded fiber industry. This work builds upon AM implementations, presenting a novel application of micro-architected lattice structure to construct fiber filtering meshes attached to drainage channels, all combined in an “Integrated Mold.” Current AM approaches have failed to build low-cost and high lifespan tools. Instead, their design approach imitates the existing MFM structure, covering a base-shaped structure with a mesh. The main disadvantage of this method is the trade-off between water drainage and stiffness. Lattice materials have shown the capability of building porous structures with high stiffness, strength-to-weight ratio, fatigue tolerance, and the capacity to control the flow of fluids. The methodology presented in this research defines a new approach for MFM design that provides a broader range of porosity and enhances water drainage capabilities without affecting structural performance. As a result, it retrieves enhanced control over the physical properties of MFM. The studies presented in this paper show the functionality of lattice structures as filters for solid particles. Moreover, it offers an immediate application of this technology. The tools developed in this research have validated their capability to withstand more than a hundred cycles as tooling for MFP, proving their functionality for prototyping stages. This result seeks to accelerate the expansion of an industry that capitalizes on locally abundant, biodegradable, and recyclable raw materials.
{"title":"Micro-Architected Lattice-Based Mesh for Fiber Filters: A Novel Additive Manufacturing Architecture for Molded Fiber Tooling","authors":"J. Dominguez, P. González","doi":"10.1115/msec2022-85305","DOIUrl":"https://doi.org/10.1115/msec2022-85305","url":null,"abstract":"\u0000 Promising developments have shown the untapped potential of additive manufacturing (AM) for fabricating molded fiber molds (MFM), a critical piece for the molded fiber industry. This work builds upon AM implementations, presenting a novel application of micro-architected lattice structure to construct fiber filtering meshes attached to drainage channels, all combined in an “Integrated Mold.” Current AM approaches have failed to build low-cost and high lifespan tools. Instead, their design approach imitates the existing MFM structure, covering a base-shaped structure with a mesh. The main disadvantage of this method is the trade-off between water drainage and stiffness.\u0000 Lattice materials have shown the capability of building porous structures with high stiffness, strength-to-weight ratio, fatigue tolerance, and the capacity to control the flow of fluids. The methodology presented in this research defines a new approach for MFM design that provides a broader range of porosity and enhances water drainage capabilities without affecting structural performance. As a result, it retrieves enhanced control over the physical properties of MFM.\u0000 The studies presented in this paper show the functionality of lattice structures as filters for solid particles. Moreover, it offers an immediate application of this technology. The tools developed in this research have validated their capability to withstand more than a hundred cycles as tooling for MFP, proving their functionality for prototyping stages. This result seeks to accelerate the expansion of an industry that capitalizes on locally abundant, biodegradable, and recyclable raw materials.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79891396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N. Khadka, Yucheng Yang, J. Haug, M. Palei, M. Rosenberger, Anthony Hoffman, E. Kinzel
Ultrafast laser processing has been widely studied for surface texturing. The complex interaction between the laser energy, plasma, and surface chemistry produces complex morphologies including Laser-Induced Periodic Surface Structures and random higher aspect ratio geometries. Laser texturing allows engineering of metallic surface’s wettability as well as the reflectance on either broadband or narrowband basis. This paper experimentally maps the laser process parameters to the surface morphology and diffuse reflectance for stainless steel, aluminum, and copper substrates. All experiments are conducted with a 1030 nm wavelength, 230 fs pulse length laser in an ambient environment. The results show how the common morphological regimes shift with material and how the reflectance varies with morphology. To further decrease the reflectance, hierarchical structures are generated by first locally micromachining the surface to form a lattice of trenches using the focused laser beam, before texturing the surface with a rastered, defocused laser beam. The micromachined features interact with laser texturing and increase light trapping on the surface. This is a function of the depth and periodicity of the hierarchical structures as well as the surface topography. This approach provides the ability to lower the surface reflectance and add an extra level of control for directing deep micro-cavities along the surface.
{"title":"Ultrafast Laser Texturing of Metal Surfaces: Effects of Process Parameters on Surface Reflectance and Possibility of Hierarchical Structuring","authors":"N. Khadka, Yucheng Yang, J. Haug, M. Palei, M. Rosenberger, Anthony Hoffman, E. Kinzel","doi":"10.1115/msec2022-85663","DOIUrl":"https://doi.org/10.1115/msec2022-85663","url":null,"abstract":"\u0000 Ultrafast laser processing has been widely studied for surface texturing. The complex interaction between the laser energy, plasma, and surface chemistry produces complex morphologies including Laser-Induced Periodic Surface Structures and random higher aspect ratio geometries. Laser texturing allows engineering of metallic surface’s wettability as well as the reflectance on either broadband or narrowband basis. This paper experimentally maps the laser process parameters to the surface morphology and diffuse reflectance for stainless steel, aluminum, and copper substrates. All experiments are conducted with a 1030 nm wavelength, 230 fs pulse length laser in an ambient environment. The results show how the common morphological regimes shift with material and how the reflectance varies with morphology. To further decrease the reflectance, hierarchical structures are generated by first locally micromachining the surface to form a lattice of trenches using the focused laser beam, before texturing the surface with a rastered, defocused laser beam. The micromachined features interact with laser texturing and increase light trapping on the surface. This is a function of the depth and periodicity of the hierarchical structures as well as the surface topography. This approach provides the ability to lower the surface reflectance and add an extra level of control for directing deep micro-cavities along the surface.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79978799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Joseph Tang, H. Sezer, N. Ahsan, Hossain Ahmed, S. Kaul
In this paper, maximum stresses from the Direct Metal Laser Sintering (DMLS) process are numerically calculated for each layer using a novel computational model that has been developed to capture the layer-by-layer deposition. The computational domain with all layers is modeled numerically with conduction, while using convection and radiation on the model boundaries. The phase change of the material between liquid and solid states is accounted for and the residual thermal stresses are obtained from the temperature gradient data in conjunction with Hooke’s law. The resulting maximum stress versus time behavior and maximum stress distribution patterns on each layer are complex and do not always match the scanning path. However, there is direct correspondence between the stress distribution and the scanning patterns.
{"title":"Modeling Maximum Stresses in Each Layer for Layer-by-Layer Deposition of the Direct Metal Laser Sintering Process for Different Scanning Patterns","authors":"Joseph Tang, H. Sezer, N. Ahsan, Hossain Ahmed, S. Kaul","doi":"10.1115/msec2022-85777","DOIUrl":"https://doi.org/10.1115/msec2022-85777","url":null,"abstract":"\u0000 In this paper, maximum stresses from the Direct Metal Laser Sintering (DMLS) process are numerically calculated for each layer using a novel computational model that has been developed to capture the layer-by-layer deposition. The computational domain with all layers is modeled numerically with conduction, while using convection and radiation on the model boundaries. The phase change of the material between liquid and solid states is accounted for and the residual thermal stresses are obtained from the temperature gradient data in conjunction with Hooke’s law. The resulting maximum stress versus time behavior and maximum stress distribution patterns on each layer are complex and do not always match the scanning path. However, there is direct correspondence between the stress distribution and the scanning patterns.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80328409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In corneal surgery, several incision instruments including the curvilinear or straight incision blades are required to construct a scleral tunnel to ensure that the wound is self-sealing after the operation. Bulk metallic glass (BMG) is proving to be a good candidate for making surgical blades, where sharp edges can be produced through a thermoplastic molding and a drawing process implemented by designing and controlling the drawing velocity at supercooled temperature. This article presents a mechanistic approach to obtain drawing velocity profile of drawing actuators that accommodates various shapes of the blade edges without having to carry out the entire extensional drawing process, which is extensive and tedious. To manufacture the multi-facet BMG knife blade edges that result in good quality, the velocity profile is developed based on the filament stretching process and the geometry and shape of the mold along with the blade profile to maintain the imposed flow stress during the blade edge formation. Two types of geometrical transformational features including drawing distance and offset angle of the draw direction to the profile, are considered to ensure that the flow stress of the drawing process is in the desirable Newtonian region. To demonstrate the feasibility of the proposed approach, H∞ control design is used to facilitate consistent good quality necking of the blade formation. The velocity profile of 45° and crescent BMG blades are generated and used to manufacture these blades. The 45° blade edge samples are successfully manufactured with the average of X-Z, X-Y straightness, and the edge radius of the blade of 1.4 ± 0.5 μm, 1.4 ± 0.5 μm, and 42.4 ± 2.3 nm, respectively. The crescent blade edge samples are manufactured with roundness deviation, and the edge radius of the blade of 5.4 ± 1.6 μm, and 35.7 ± 4.2 nm, respectively. The effects of BMG sample temperature settings on the quality of the manufactured blades are presented.
{"title":"Thermoplastic Forming Process for Manufacturing Arbitrary Blade Edge Geometries From Bulk Metallic Glass","authors":"N. Dancholvichit, S. Salapaka, S. Kapoor","doi":"10.1115/msec2022-80859","DOIUrl":"https://doi.org/10.1115/msec2022-80859","url":null,"abstract":"\u0000 In corneal surgery, several incision instruments including the curvilinear or straight incision blades are required to construct a scleral tunnel to ensure that the wound is self-sealing after the operation. Bulk metallic glass (BMG) is proving to be a good candidate for making surgical blades, where sharp edges can be produced through a thermoplastic molding and a drawing process implemented by designing and controlling the drawing velocity at supercooled temperature. This article presents a mechanistic approach to obtain drawing velocity profile of drawing actuators that accommodates various shapes of the blade edges without having to carry out the entire extensional drawing process, which is extensive and tedious. To manufacture the multi-facet BMG knife blade edges that result in good quality, the velocity profile is developed based on the filament stretching process and the geometry and shape of the mold along with the blade profile to maintain the imposed flow stress during the blade edge formation. Two types of geometrical transformational features including drawing distance and offset angle of the draw direction to the profile, are considered to ensure that the flow stress of the drawing process is in the desirable Newtonian region. To demonstrate the feasibility of the proposed approach, H∞ control design is used to facilitate consistent good quality necking of the blade formation. The velocity profile of 45° and crescent BMG blades are generated and used to manufacture these blades. The 45° blade edge samples are successfully manufactured with the average of X-Z, X-Y straightness, and the edge radius of the blade of 1.4 ± 0.5 μm, 1.4 ± 0.5 μm, and 42.4 ± 2.3 nm, respectively. The crescent blade edge samples are manufactured with roundness deviation, and the edge radius of the blade of 5.4 ± 1.6 μm, and 35.7 ± 4.2 nm, respectively. The effects of BMG sample temperature settings on the quality of the manufactured blades are presented.","PeriodicalId":45459,"journal":{"name":"Journal of Micro and Nano-Manufacturing","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78080995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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