Colin Warn, A. Sherehiy, Moath H. A. Alqatamin, Brooke Ritz, Ruoshi Zhang, S. Chowdhury, Danming Wei, D. Popa
In this paper, we propose a method for tracking a microrobot’s three-dimensional position using microscope machine vision. The microrobot, theSolid Articulated Four Axis Microrobot (sAFAM), is being developed to enable the assembly and manipulation of micro and nanoscale objects. In the future, arrays of sAFAMS working together can be integrated into a wafer-scale nanofactory, Prior to use, microrobots in this microfactory need calibration, which can be achieved using the proposed measurement technique. Our approach enables faster and more accurate mapping of microrobot translations and rotations, and orders of magnitude larger datasets can be created by automation. Cameras feeds on a custom microscopy system is fed into a data processing pipeline that enables tracking of the microrobot in real-time. This particular machine vision method was implemented with a help of OpenCV and Python and can be used to track the movement of other micrometer-sized features. Additionally, a script was created to enable automated repeatability tests for each of the six trajectories traversable by the robot. A more precise microrobot workable area was also determined thanks to the significantly larger datasets enabled by the combined automation and machine vision approaches.
{"title":"Machine Vision Tracking and Automation of a Microrobot (sAFAM)","authors":"Colin Warn, A. Sherehiy, Moath H. A. Alqatamin, Brooke Ritz, Ruoshi Zhang, S. Chowdhury, Danming Wei, D. Popa","doi":"10.1115/msec2022-85424","DOIUrl":"https://doi.org/10.1115/msec2022-85424","url":null,"abstract":"\u0000 In this paper, we propose a method for tracking a microrobot’s three-dimensional position using microscope machine vision. The microrobot, theSolid Articulated Four Axis Microrobot (sAFAM), is being developed to enable the assembly and manipulation of micro and nanoscale objects. In the future, arrays of sAFAMS working together can be integrated into a wafer-scale nanofactory, Prior to use, microrobots in this microfactory need calibration, which can be achieved using the proposed measurement technique. Our approach enables faster and more accurate mapping of microrobot translations and rotations, and orders of magnitude larger datasets can be created by automation. Cameras feeds on a custom microscopy system is fed into a data processing pipeline that enables tracking of the microrobot in real-time. This particular machine vision method was implemented with a help of OpenCV and Python and can be used to track the movement of other micrometer-sized features. Additionally, a script was created to enable automated repeatability tests for each of the six trajectories traversable by the robot. A more precise microrobot workable area was also determined thanks to the significantly larger datasets enabled by the combined automation and machine vision approaches.","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":"80545364","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}
High strength and lightweight continuous carbon fiber reinforced composites are desirable structural materials for applications in various industries including aerospace, automotive, and defense. Additive manufacturing (AM) of such important materials may provide multiple benefits including reduced cost, improved manufacturing efficiency, and the ability to fabricate complex structures not possible with traditional methods. Despite these benefits, a significant challenge with AM of continuous carbon fiber composites is poor impregnation of the fiber bundle with matrix material. When there is a lack of matrix material, voids develop within the fiber bundle and reduce mechanical properties of the composite including strength and stiffness. To minimize void formation, low speed manufacturing is typically necessary to facilitate impregnation. In this work, it was shown that fiber bundle impregnation can be significantly improved by applying thin, nanoporous coatings to the continuous fiber bundle. Using an electrophoretic deposition process, the coating microstructure, including thickness and nano pore size, was easily controlled through effective tuning of process parameters. Ultimately, individually coated carbon fibers were obtained and provided improvements in fiber bundle impregnation without sacrificing the flexibility of the fiber bundle. A highly absorbent yet flexible fiber bundle was desirable for 3D printing applications and would facilitate fabrication of complex geometries. With such tailored nanoporous coatings, fifteen-fold improvement in resin absorption time due was observed due to improved wicking by the nanoporous structure. Such improvements in absorption characteristics have a great potential for drop on demand or other resin-based 3D printing techniques. Furthermore, mechanical characterization demonstrated the potential of nanoporous coatings for additive manufacturing of high performance carbon fiber reinforced composites.
{"title":"Nanoporous Carbon Nanotube Coating for 3D Printing of High-Performance Continuous Fiber Reinforced Polymer Composites","authors":"J. M. Pappas, Xiangyang Dong","doi":"10.1115/msec2022-85758","DOIUrl":"https://doi.org/10.1115/msec2022-85758","url":null,"abstract":"\u0000 High strength and lightweight continuous carbon fiber reinforced composites are desirable structural materials for applications in various industries including aerospace, automotive, and defense. Additive manufacturing (AM) of such important materials may provide multiple benefits including reduced cost, improved manufacturing efficiency, and the ability to fabricate complex structures not possible with traditional methods. Despite these benefits, a significant challenge with AM of continuous carbon fiber composites is poor impregnation of the fiber bundle with matrix material. When there is a lack of matrix material, voids develop within the fiber bundle and reduce mechanical properties of the composite including strength and stiffness. To minimize void formation, low speed manufacturing is typically necessary to facilitate impregnation. In this work, it was shown that fiber bundle impregnation can be significantly improved by applying thin, nanoporous coatings to the continuous fiber bundle. Using an electrophoretic deposition process, the coating microstructure, including thickness and nano pore size, was easily controlled through effective tuning of process parameters. Ultimately, individually coated carbon fibers were obtained and provided improvements in fiber bundle impregnation without sacrificing the flexibility of the fiber bundle. A highly absorbent yet flexible fiber bundle was desirable for 3D printing applications and would facilitate fabrication of complex geometries. With such tailored nanoporous coatings, fifteen-fold improvement in resin absorption time due was observed due to improved wicking by the nanoporous structure. Such improvements in absorption characteristics have a great potential for drop on demand or other resin-based 3D printing techniques. Furthermore, mechanical characterization demonstrated the potential of nanoporous coatings for additive manufacturing of high performance carbon fiber reinforced composites.","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":"83731018","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}
Two-photon lithography (TPL) is a photopolymerization-based additive manufacturing technique capable of fabricating complex 3D structures with submicron features. Projection TPL (P-TPL) is a specific implementation that leverages projection-based parallelization to increase the rate of printing by three orders of magnitude. However, a practical limitation of P-TPL is the high shrinkage of the printed microstructures that is caused by the relatively low degree of polymerization in the as-printed parts. Unlike traditional stereolithography (SLA) methods and conventional TPL, most of the polymerization in P-TPL occurs through dark reactions while the light source is off, thereby resulting in a lower degree of polymerization. In this study, we empirically investigated the parameters of the P-TPL process that affect shrinkage. We observed that the shrinkage reduces with an increase in the duration of laser exposure and with a reduction of layer spacing. To broaden the design space, we explored a photochemical post-processing technique that involves further curing the printed structures using UV light while submerging them in a solution of a photoinitiator. With this post-processing, we were able to reduce the areal shrinkage from more than 45% to 1% without limiting the geometric design space. This shows that P-TPL can achieve high dimensional accuracy while taking advantage of the high throughput when compared to conventional serial TPL. Furthermore, P-TPL has a higher resolution when compared to the conventional SLA prints at a similar shrinkage rate.
{"title":"Minimizing Shrinkage in Microstructures Printed With Projection Two-Photon Lithography","authors":"Harnjoo Kim, S. Saha","doi":"10.1115/msec2022-86076","DOIUrl":"https://doi.org/10.1115/msec2022-86076","url":null,"abstract":"\u0000 Two-photon lithography (TPL) is a photopolymerization-based additive manufacturing technique capable of fabricating complex 3D structures with submicron features. Projection TPL (P-TPL) is a specific implementation that leverages projection-based parallelization to increase the rate of printing by three orders of magnitude. However, a practical limitation of P-TPL is the high shrinkage of the printed microstructures that is caused by the relatively low degree of polymerization in the as-printed parts. Unlike traditional stereolithography (SLA) methods and conventional TPL, most of the polymerization in P-TPL occurs through dark reactions while the light source is off, thereby resulting in a lower degree of polymerization. In this study, we empirically investigated the parameters of the P-TPL process that affect shrinkage. We observed that the shrinkage reduces with an increase in the duration of laser exposure and with a reduction of layer spacing. To broaden the design space, we explored a photochemical post-processing technique that involves further curing the printed structures using UV light while submerging them in a solution of a photoinitiator. With this post-processing, we were able to reduce the areal shrinkage from more than 45% to 1% without limiting the geometric design space. This shows that P-TPL can achieve high dimensional accuracy while taking advantage of the high throughput when compared to conventional serial TPL. Furthermore, P-TPL has a higher resolution when compared to the conventional SLA prints at a similar shrinkage rate.","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":"74803243","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}
Ishrat Jahan Biswas, Enrique Contreras Lopez, F. Ahmed, Jianzhi Li
Laser direct writing (LDW) is a fast and cost-effective method for printing conductive patterns in flexible polymer substrates. The electrical, chemical, and mechanical properties of polyimide (PI) make it an attractive material choice for laser writing of conductive circuits in such polymer. Electrically insulating PI has shown great potential for flexible printed electronics as LDW enables selective carbonization in the bulk of such material leading to the formation of conductive lines. However, existing studies in this area reveal a few key limitations of this approach including limited conductivity of written structures and fragility of carbonized PI. Therefore, more research is required to overcome those limitations and reap the benefits of the LDW approach in writing flexible electronic circuits in PI. The proposed study investigates potential approaches to enhance the electrical conductivity of femtosecond laser written bulk carbon structures in PI films. Deposition of laser energy was varied by changing key process parameters such as pulse energy, pulse picker divider, and hatch distance of laser scan to maximize the conductively of the carbon structure. The experimental findings show a strong dependency of laser energy deposition on the conductivity carbon structures in PI films. To further enhance the electrical conductivity of laser written structures, the feasibility of adding copper microparticles to the PI solution and subsequent laser carbonization was studied. The proposed LDW of conductive lines has potential in flexible electronic circuits and sensing applications.
{"title":"Ultrafast Laser Direct Writing of Conductive Patterns on Polyimide Substrate","authors":"Ishrat Jahan Biswas, Enrique Contreras Lopez, F. Ahmed, Jianzhi Li","doi":"10.1115/msec2022-85684","DOIUrl":"https://doi.org/10.1115/msec2022-85684","url":null,"abstract":"\u0000 Laser direct writing (LDW) is a fast and cost-effective method for printing conductive patterns in flexible polymer substrates. The electrical, chemical, and mechanical properties of polyimide (PI) make it an attractive material choice for laser writing of conductive circuits in such polymer. Electrically insulating PI has shown great potential for flexible printed electronics as LDW enables selective carbonization in the bulk of such material leading to the formation of conductive lines. However, existing studies in this area reveal a few key limitations of this approach including limited conductivity of written structures and fragility of carbonized PI. Therefore, more research is required to overcome those limitations and reap the benefits of the LDW approach in writing flexible electronic circuits in PI. The proposed study investigates potential approaches to enhance the electrical conductivity of femtosecond laser written bulk carbon structures in PI films. Deposition of laser energy was varied by changing key process parameters such as pulse energy, pulse picker divider, and hatch distance of laser scan to maximize the conductively of the carbon structure. The experimental findings show a strong dependency of laser energy deposition on the conductivity carbon structures in PI films. To further enhance the electrical conductivity of laser written structures, the feasibility of adding copper microparticles to the PI solution and subsequent laser carbonization was studied. The proposed LDW of conductive lines has potential in flexible electronic circuits and sensing applications.","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":"78091340","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}
Nearly 1 in 4 women undergo surgery for pelvic organ prolapse or urinary incontinence in the US. The weakened pelvic floor, which could be caused by childbirth injury, aging, or obesity, fails to support the pelvic organs, resulting in urinary incontinence, sexual difficulties, and pelvic organ prolapse (POP). Polypropylene (PP) meshes are often used in reconstructive surgeries as a reinforcement to provide long-term, durable support. However, commercial polypropylene meshes have a risk of complications, such as pain, mesh erosion, and infection. The United States Food and Drug Administration (FDA) has consequently re-classified the polypropylene mesh as a high-risk device. Therefore, the need for new meshes to cure POP with a rapid prototyping technique is urgent, especially for personalized medicine. Therefore, we developed a new implantable mesh using biocompatible polymers (e.g., gelatin, polyvinyl alcohol (PVA), chitosan) with controlled bonding strength and tunable lifetime. Our group has leveraged additive manufacturing for porous scaffold structures beneficial for cell attachment and nutrition transmission. Our POP scaffold mesh has demonstrated high biocompatibility and controlled biodegradability. We will also leverage our manufacturing expertise and clinical partnerships to examine cell proliferation and differentiation for tissue regeneration. Our advanced manufacturing method is compatible with other materials and has potential use in layered structures for dental, heart, or bone engineering applications.
{"title":"3D Printed Pelvic Organ Prolapse (POP) Tissue Scaffolds","authors":"Yuxiang Zhu, Dharneedar Ravichandran, Kenan Song","doi":"10.1115/msec2022-85062","DOIUrl":"https://doi.org/10.1115/msec2022-85062","url":null,"abstract":"\u0000 Nearly 1 in 4 women undergo surgery for pelvic organ prolapse or urinary incontinence in the US. The weakened pelvic floor, which could be caused by childbirth injury, aging, or obesity, fails to support the pelvic organs, resulting in urinary incontinence, sexual difficulties, and pelvic organ prolapse (POP). Polypropylene (PP) meshes are often used in reconstructive surgeries as a reinforcement to provide long-term, durable support. However, commercial polypropylene meshes have a risk of complications, such as pain, mesh erosion, and infection. The United States Food and Drug Administration (FDA) has consequently re-classified the polypropylene mesh as a high-risk device. Therefore, the need for new meshes to cure POP with a rapid prototyping technique is urgent, especially for personalized medicine.\u0000 Therefore, we developed a new implantable mesh using biocompatible polymers (e.g., gelatin, polyvinyl alcohol (PVA), chitosan) with controlled bonding strength and tunable lifetime. Our group has leveraged additive manufacturing for porous scaffold structures beneficial for cell attachment and nutrition transmission. Our POP scaffold mesh has demonstrated high biocompatibility and controlled biodegradability. We will also leverage our manufacturing expertise and clinical partnerships to examine cell proliferation and differentiation for tissue regeneration. Our advanced manufacturing method is compatible with other materials and has potential use in layered structures for dental, heart, or bone engineering applications.","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":"90215629","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}
Copper (Cu) and Tin (Sn) were low-pressure cold sprayed onto polyamide 6 (PA 6) and polypropylene (PP) substrates. The first layer of Sn and Cu was built onto the polymer substrate and continued as an alternative layer of Cu and Sn build-up under controlled process parameters. The chronological order of either first spraying Cu or Sn does not hinder building a coated layer on the PA 6 and PP substrate. The coating thickness can reach as thick as 100 μm of the PA 6 (Cu/Sn/Cu) layer. Results show the potential ability for additive manufacturing using polymeric templates. The cold spray kinetic bonding of the metals avoids any intermediate phase formation. The mechanical performance of the coated material remains the same as the deposition process does not degrade bulk substrates. The contour of the interface and the surface roughness resulting from the cold spray coating process lead to a deformed surface layer of the polymer on the particle size of the powder used for cold spraying. While the metallic coating deforms via plastic deformation and cracking, the through-thickness cracks, which primarily are perpendicular to the loading direction, do not span the width of the coating due to the tortuous nature of the microstructure. The advantage provides electrical conductivity to strains of up to 10% and maintains a low electrical resistance.
{"title":"Cold Spray Multilayer Metal Build-Up on a Polymeric Substrate","authors":"J. Tsai, M. Jun, D. Bahr","doi":"10.1115/msec2022-80318","DOIUrl":"https://doi.org/10.1115/msec2022-80318","url":null,"abstract":"\u0000 Copper (Cu) and Tin (Sn) were low-pressure cold sprayed onto polyamide 6 (PA 6) and polypropylene (PP) substrates. The first layer of Sn and Cu was built onto the polymer substrate and continued as an alternative layer of Cu and Sn build-up under controlled process parameters. The chronological order of either first spraying Cu or Sn does not hinder building a coated layer on the PA 6 and PP substrate. The coating thickness can reach as thick as 100 μm of the PA 6 (Cu/Sn/Cu) layer. Results show the potential ability for additive manufacturing using polymeric templates. The cold spray kinetic bonding of the metals avoids any intermediate phase formation. The mechanical performance of the coated material remains the same as the deposition process does not degrade bulk substrates. The contour of the interface and the surface roughness resulting from the cold spray coating process lead to a deformed surface layer of the polymer on the particle size of the powder used for cold spraying. While the metallic coating deforms via plastic deformation and cracking, the through-thickness cracks, which primarily are perpendicular to the loading direction, do not span the width of the coating due to the tortuous nature of the microstructure. The advantage provides electrical conductivity to strains of up to 10% and maintains a low electrical resistance.","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":"84794783","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}
The overarching goal of this research work is to synthesize and fabricate mechanically robust, dimensionally accurate, and porous bone scaffolds for the clinical treatment of osseous fractures, defects, and diseases. In pursuit of this goal, the objective of the work is to investigate the influence of hydroxyapatite (HA) as well as polysaccharide concentration on the mechanical properties of bone scaffolds, fabricated using freeze drying process. Freeze drying or lyophilization has emerged as a robust method for the fabrication of a broad spectrum of tissue constructs. Freeze Drying allows for multi-material fabrication of structures with complex pore morphology for soft and hard tissue engineering applications. However, the process is intrinsically complex; the complexity of the process, to a great extent, stems from complex physical phenomena (such as sublimation) as well as material-process interactions, which may adversely affect the mechanical properties, the surface morphology, and ultimately the functional characteristics of fabricated bone scaffolds. Consequently, physics-based process and material characterization would be an inevitable need. In this study, the influence of HA and polysaccharide concentration was investigated using a central composite design (CCD). The concentration of both HA and polysaccharide was changed in the range of 5%–15% with the aim to obtain mechanically robust structures. 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, mechanically strong, and porous bone-like scaffolds with tunable medical and functional properties.
{"title":"Investigation of the Influence of Hydroxyapatite and Polysaccharide Concentration on the Mechanical Properties of Bone Scaffolds, Fabricated Using Freeze Drying Process","authors":"Tanner Ekstrom, James B. Day, Roozbeh Salary","doi":"10.1115/msec2022-85437","DOIUrl":"https://doi.org/10.1115/msec2022-85437","url":null,"abstract":"The overarching goal of this research work is to synthesize and fabricate mechanically robust, dimensionally accurate, and porous bone scaffolds for the clinical treatment of osseous fractures, defects, and diseases. In pursuit of this goal, the objective of the work is to investigate the influence of hydroxyapatite (HA) as well as polysaccharide concentration on the mechanical properties of bone scaffolds, fabricated using freeze drying process. Freeze drying or lyophilization has emerged as a robust method for the fabrication of a broad spectrum of tissue constructs. Freeze Drying allows for multi-material fabrication of structures with complex pore morphology for soft and hard tissue engineering applications. However, the process is intrinsically complex; the complexity of the process, to a great extent, stems from complex physical phenomena (such as sublimation) as well as material-process interactions, which may adversely affect the mechanical properties, the surface morphology, and ultimately the functional characteristics of fabricated bone scaffolds. Consequently, physics-based process and material characterization would be an inevitable need. In this study, the influence of HA and polysaccharide concentration was investigated using a central composite design (CCD). The concentration of both HA and polysaccharide was changed in the range of 5%–15% with the aim to obtain mechanically robust structures. 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, mechanically strong, and porous bone-like 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":"85246510","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}
Yujie Shan, Aravind Krishnakumar, Zehan Qin, Huachao Mao
Real-time and in-situ printing performance diagnostic in vat photopolymerization is critical to control printing quality, improve process reliability, and reduce wasted time and materials. This paper proposed a low-cost smart resin vat to monitor the printing process and detect the printing faults. Built on a conventional vat photopolymerization process, we added equally spaced thermistors along the edges of the resin vat. During printing, polymerization heat transferred to the edges of the resin vat, which increased thermistors’ temperature and enhanced resistances. The heat flux received at each thermistor varied with the distance to the place of photopolymerization. The temperature profiles of all thermistors were determined by the curing image pattern in each layer, and vice versa. Machine learning algorithms were leveraged to infer the printing status from the measured temperatures of these thermistors. Specifically, we proposed a simple and robust Failure Index to detect if the printing was active or terminated. Gaussian process regression was utilized to predict the printing area using the temperature recordings within a layer. The model was trained, validated, and tested using the data set collected by printing six parts. Different printing abnormalities, including printing failures, manual printing pause, and missing features (incorrect printing area), were successfully detected. The proposed approach modified the resin vat only and could be easily applied to all vat photopolymerization processes, including SLA, DLP, and LCD based 3D printing. The limitation and future work are also highlighted.
{"title":"Smart Resin Vat: Real-Time Detecting Failures, Defects, and Curing Area in Vat Photopolymerization 3D Printing","authors":"Yujie Shan, Aravind Krishnakumar, Zehan Qin, Huachao Mao","doi":"10.1115/msec2022-85691","DOIUrl":"https://doi.org/10.1115/msec2022-85691","url":null,"abstract":"\u0000 Real-time and in-situ printing performance diagnostic in vat photopolymerization is critical to control printing quality, improve process reliability, and reduce wasted time and materials. This paper proposed a low-cost smart resin vat to monitor the printing process and detect the printing faults. Built on a conventional vat photopolymerization process, we added equally spaced thermistors along the edges of the resin vat. During printing, polymerization heat transferred to the edges of the resin vat, which increased thermistors’ temperature and enhanced resistances. The heat flux received at each thermistor varied with the distance to the place of photopolymerization. The temperature profiles of all thermistors were determined by the curing image pattern in each layer, and vice versa. Machine learning algorithms were leveraged to infer the printing status from the measured temperatures of these thermistors. Specifically, we proposed a simple and robust Failure Index to detect if the printing was active or terminated. Gaussian process regression was utilized to predict the printing area using the temperature recordings within a layer. The model was trained, validated, and tested using the data set collected by printing six parts. Different printing abnormalities, including printing failures, manual printing pause, and missing features (incorrect printing area), were successfully detected. The proposed approach modified the resin vat only and could be easily applied to all vat photopolymerization processes, including SLA, DLP, and LCD based 3D printing. The limitation and future work are also highlighted.","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":"78764449","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}
Hydrothermal-assisted jet fusion (HJF) process is a new additive manufacturing (AM) method for ceramics, which is capable of fabricating ceramic 3D structures without the need for organic binders. The HJF process selectively deposits a water-based solution into a ceramic powder bed in a layer-by-layer manner and fuses particles together through a hydrothermal mechanism. Since no organic binder is used in the HJF process, such a binder-free AM method can produce ceramic parts with less energy consumed for binder removal and has the potential to reach the material’s theoretical properties such as full density and exceptional mechanical strength. Nevertheless, the fabricated parts by the HJF process still suffers from issues, such as over fusion base-layer damage, pattern shifting, etc. In this paper, the effects of process parameters (e.g., stroke, droplet size, press number, final press, etc.) on the fabrication quality (e.g., diffusion behavior of deposited inks and shape fidelity of the fabricated parts, etc.) of the HJF process are studied. Optimum process settings are identified to alleviate those quality issues, and 3D structures with high shape fidelity were successfully fabricated to highlight the capability of the HJF process in achieving ceramic 3D structures with high accuracy and high performance.
{"title":"Process Optimization for Hydrothermal-Assisted Jet Fusion Additive Manufacturing of Ceramics","authors":"F. Fei, L. Kirby, Xuan Song","doi":"10.1115/msec2022-85772","DOIUrl":"https://doi.org/10.1115/msec2022-85772","url":null,"abstract":"\u0000 Hydrothermal-assisted jet fusion (HJF) process is a new additive manufacturing (AM) method for ceramics, which is capable of fabricating ceramic 3D structures without the need for organic binders. The HJF process selectively deposits a water-based solution into a ceramic powder bed in a layer-by-layer manner and fuses particles together through a hydrothermal mechanism. Since no organic binder is used in the HJF process, such a binder-free AM method can produce ceramic parts with less energy consumed for binder removal and has the potential to reach the material’s theoretical properties such as full density and exceptional mechanical strength. Nevertheless, the fabricated parts by the HJF process still suffers from issues, such as over fusion base-layer damage, pattern shifting, etc. In this paper, the effects of process parameters (e.g., stroke, droplet size, press number, final press, etc.) on the fabrication quality (e.g., diffusion behavior of deposited inks and shape fidelity of the fabricated parts, etc.) of the HJF process are studied. Optimum process settings are identified to alleviate those quality issues, and 3D structures with high shape fidelity were successfully fabricated to highlight the capability of the HJF process in achieving ceramic 3D structures with high accuracy and high performance.","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":"88344954","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}
Composite and hybrid materials displaying layered structures have broad applications in structural composites, fire retardant barriers, tissue scaffolds, and microelectronics. Inspired by biosystems, in this study, we explore the invention of a new 3D printing principle that can produce layered structures similar to those in trees, overcoming the bottleneck in additive manufacturing to include multi-materials. We use polyvinyl alcohol (PVA) and carbon nanotubes (CNTs) as material examples for producing alternating layers. With the unique 3D printing platform, Multiphase Direct Ink Writing (MDIW), the optimized dispersion quality and rheology behaviors allow the number of layers within an individual printing line to change between 4 and 512 layers. The mechanical tests consistently increased young’s modulus and ultimate tensile strength with decreased layer thickness and dispersion quality. The best-performed composites have 128 layers in one printing line, beyond which the dispersion of CNTs deteriorated due to aggregates. Due to the thin layer thickness, the improved composite mechanics relate to the closely packed CNTs and their alignment. Moreover, we will also demonstrate this MDIW printing with different polymers (e.g., thermoplastic urethane and polylactic acid) and nanoparticles (e.g., iron oxide, carbon fibers) for mechanical enhancement and intelligent behaviors. This research demonstrated one new 3D printing method, MDIW, that can fabricate multilayered composites containing well-managed content in each layer. Our advanced manufacturing method is compatible with other materials and has potential use in batteries, supercapacitors, solar cells, regenerative medicine, and energetic systems requiring layered structures.
{"title":"One-Step 3D Printed Layers Along With xy-in Plane Directions for Enhanced Multifunctional Nanocomposites","authors":"Dharneedar Ravichandran, Kenan Song","doi":"10.1115/msec2022-85056","DOIUrl":"https://doi.org/10.1115/msec2022-85056","url":null,"abstract":"\u0000 Composite and hybrid materials displaying layered structures have broad applications in structural composites, fire retardant barriers, tissue scaffolds, and microelectronics. Inspired by biosystems, in this study, we explore the invention of a new 3D printing principle that can produce layered structures similar to those in trees, overcoming the bottleneck in additive manufacturing to include multi-materials. We use polyvinyl alcohol (PVA) and carbon nanotubes (CNTs) as material examples for producing alternating layers. With the unique 3D printing platform, Multiphase Direct Ink Writing (MDIW), the optimized dispersion quality and rheology behaviors allow the number of layers within an individual printing line to change between 4 and 512 layers. The mechanical tests consistently increased young’s modulus and ultimate tensile strength with decreased layer thickness and dispersion quality. The best-performed composites have 128 layers in one printing line, beyond which the dispersion of CNTs deteriorated due to aggregates. Due to the thin layer thickness, the improved composite mechanics relate to the closely packed CNTs and their alignment.\u0000 Moreover, we will also demonstrate this MDIW printing with different polymers (e.g., thermoplastic urethane and polylactic acid) and nanoparticles (e.g., iron oxide, carbon fibers) for mechanical enhancement and intelligent behaviors. This research demonstrated one new 3D printing method, MDIW, that can fabricate multilayered composites containing well-managed content in each layer. Our advanced manufacturing method is compatible with other materials and has potential use in batteries, supercapacitors, solar cells, regenerative medicine, and energetic systems requiring layered structures.","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":"89172415","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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