Polymer Micro/Nanofabrication and Manufacturing II

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Processing and Engineering".

Deadline for manuscript submissions: 31 December 2024 | Viewed by 14957

Special Issue Editor


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Guest Editor
Department of Chemical Engineering, National Cheng Kung University, Tainan 717005, Taiwan
Interests: micro/nanofabrication; polymer microembossing; microfluidics; BioMEMS
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Special Issue Information

Dear Colleagues,

In the field of microfabrication, the utilization of polymers as the substrate material has compelling advantages over other materials owing to their versatile properties, such as low protein adsorption, biocompatibility, surface functionality/modification, mechanical strength, chemical resistance, and low electrical and thermal conductivities. Moreover, the mass production capability of polymeric materials makes it possible to manufacture low-cost products such that they become affordable for one-time use, which is necessary in clinical diagnostics and many biomedical applications. The global market size for emerging gadgets like microfluidic devices and BioMEMS is estimated to be around $15 billion by 2025, wherein the polymer segment accounts for a significant share. Therefore, the aim of this Special Issue is to collect ongoing scientific research on and developments in polymer microfabrication and manufacturing for its potential application in every field of interest. Research as well as review articles are welcome.

Prof. Dr. Yi-Je Juang
Guest Editor

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Keywords

  • microfabrication
  • polymer
  • elastomer
  • micro-embossing
  • imprinting
  • micro-injection molding
  • resin transfer molding
  • roll-to-roll
  • roll-to-plate
  • mold making
  • numerical simulation
  • modeling
  • rheological properties of polymers
  • novel technique
  • manufacturing

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Related Special Issue

Published Papers (9 papers)

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Research

17 pages, 17877 KiB  
Article
Enhancing EDM Productivity for Plastic Injection Mold Manufacturing: An Experimental Optimization Study
by Aurel Mihail Titu and Alina Bianca Pop
Polymers 2024, 16(21), 3019; https://doi.org/10.3390/polym16213019 - 28 Oct 2024
Viewed by 320
Abstract
Electrical erosion molding (EDM) is an unconventional machining technology widely used in the manufacture of injection molds for plastics injection molding for the creation of complex cavities and geometries. However, EDM productivity can be challenging, directly influencing mold manufacturing time and cost. This [...] Read more.
Electrical erosion molding (EDM) is an unconventional machining technology widely used in the manufacture of injection molds for plastics injection molding for the creation of complex cavities and geometries. However, EDM productivity can be challenging, directly influencing mold manufacturing time and cost. This work aims to improve EDM productivity in the context of mold manufacturing for plastics injection molding. The research focuses on the optimization of processing parameters and strategies to reduce manufacturing time and increase process efficiency. Through a rigorous experimental approach, this work demonstrates that the optimization of EDM parameters and strategies can lead to significant productivity gains in the manufacture of plastic injection molds without compromising part quality and accuracy. This research involved a series of controlled experiments on a Mitsubishi EA28V Advance die-sinking EDM machine. Different combinations of pre-cutting parameters and processing strategies were investigated using copper electrodes on a heat-treated steel plate. Productivity was evaluated by measuring the volume of material removed, and geometrical accuracy was checked on a coordinate measuring machine. The experimental results showed a significant increase in productivity (up to 61%) by using the “processing speed priority” function of the EDM machine, with minimal impact on geometric accuracy. Furthermore, the optimized parameters led to an average reduction of 12% in dimensional deviations, indicating improved geometric accuracy of the machined parts. This paper also provides practical recommendations on the selection of optimal EDM processing parameters and strategies, depending on the specific requirements of plastic injection mold manufacturing. Full article
(This article belongs to the Special Issue Polymer Micro/Nanofabrication and Manufacturing II)
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19 pages, 1904 KiB  
Article
3D-Printed Hydrogels as Photothermal Actuators
by Melanie M. Ghelardini, Martin Geisler, Niclas Weigel, Jameson P. Hankwitz, Nicolas Hauck, Jonas Schubert, Andreas Fery, Joseph B. Tracy and Julian Thiele
Polymers 2024, 16(14), 2032; https://doi.org/10.3390/polym16142032 - 17 Jul 2024
Viewed by 1357
Abstract
Thermoresponsive hydrogels were 3D-printed with embedded gold nanorods (GNRs), which enable shape change through photothermal heating. GNRs were functionalized with bovine serum albumin and mixed with a photosensitizer and poly(N-isopropylacrylamide) (PNIPAAm) macromer, forming an ink for 3D printing by direct ink [...] Read more.
Thermoresponsive hydrogels were 3D-printed with embedded gold nanorods (GNRs), which enable shape change through photothermal heating. GNRs were functionalized with bovine serum albumin and mixed with a photosensitizer and poly(N-isopropylacrylamide) (PNIPAAm) macromer, forming an ink for 3D printing by direct ink writing. A macromer-based approach was chosen to provide good microstructural homogeneity and optical transparency of the unloaded hydrogel in its swollen state. The ink was printed into an acetylated gelatin hydrogel support matrix to prevent the spreading of the low-viscosity ink and provide mechanical stability during printing and concurrent photocrosslinking. Acetylated gelatin hydrogel was introduced because it allows for melting and removal of the support structure below the transition temperature of the crosslinked PNIPAAm structure. Convective and photothermal heating were compared, which both triggered the phase transition of PNIPAAm and induced reversible shrinkage of the hydrogel–GNR composite for a range of GNR loadings. During reswelling after photothermal heating, some structures formed an internally buckled state, where minor mechanical agitation recovered the unbuckled structure. The BSA-GNRs did not leach out of the structure during multiple cycles of shrinkage and reswelling. This work demonstrates the promise of 3D-printed, photoresponsive structures as hydrogel actuators. Full article
(This article belongs to the Special Issue Polymer Micro/Nanofabrication and Manufacturing II)
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14 pages, 12957 KiB  
Article
Fabrication of Nanogroove Arrays on Acrylic Film Using Micro-Embossing Technique
by Chana Raksiri, Potejana Potejanasak and Thitipoom Dokyor
Polymers 2023, 15(18), 3804; https://doi.org/10.3390/polym15183804 - 18 Sep 2023
Cited by 1 | Viewed by 1195
Abstract
The fabrication of nanostructures is of great importance in producing biomedical devices. Significantly, the nanostructure of the polymeric film has a significant impact on the physical and biophysical behavior of the biomolecules. This study presents an efficient nanofabrication method of nanogroove structures on [...] Read more.
The fabrication of nanostructures is of great importance in producing biomedical devices. Significantly, the nanostructure of the polymeric film has a significant impact on the physical and biophysical behavior of the biomolecules. This study presents an efficient nanofabrication method of nanogroove structures on an acrylic film by the micro-embossing process. In this method, a master mold was made from a thermos oxide silicon substrate using photolithography and etching techniques. An isotropic optical polymethyl methacrylate (PMMA) film is used in the experiment. The acrylic film is known for its excellent optical properties in products such as optical lenses, medical devices, and various general purpose engineering plastics. Then, the micro-embossing process was realized to fabricate nanogroove patterns on an acrylic film by using a micro-embossing machine. However, the morphology of the nanopatterns on an acrylic film was characterized by using an atomic force microscope to measure the dimensions of the nanogroove patterns. The impact of embossing temperature on the morphology of nanogroove patterns on acrylic film is experimentally investigated. The results show that when the embossing temperature is too small, the pattern is not fully formed, and slipping occurs in nanopatterns on the acrylic film. On the other hand, the effect of increasing the embossing temperature on the morphology of nanogrooves agrees with the master mold, and the crests between the nanogrooves form straight edges. It should be noted that the micro-embossing temperature also strongly influences the transferability of nanopatterns on an acrylic film. The technique has great potential for rapidly fabricating nanostructure patterns on acrylic film. Full article
(This article belongs to the Special Issue Polymer Micro/Nanofabrication and Manufacturing II)
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17 pages, 6757 KiB  
Article
On-Demand Tunability of Microphase Separation Structure of 3D Printing Material by Reversible Addition/Fragmentation Chain Transfer Polymerization
by Masaru Mukai, Mituki Sato, Wakana Miyadai and Shoji Maruo
Polymers 2023, 15(17), 3519; https://doi.org/10.3390/polym15173519 - 23 Aug 2023
Cited by 1 | Viewed by 1410
Abstract
Controlling the phase-separated structure of polymer alloys is a promising method for tailoring the properties of polymers. However, controlling the morphology of phase-separated structures is challenging. Recently, phase-separated structures have been fabricated via 3D printing; however, only a few methods that enable on-demand [...] Read more.
Controlling the phase-separated structure of polymer alloys is a promising method for tailoring the properties of polymers. However, controlling the morphology of phase-separated structures is challenging. Recently, phase-separated structures have been fabricated via 3D printing; however, only a few methods that enable on-demand control of phase separation have been reported. In this study, laser-scanning stereolithography, a vat photopolymerization method, is used to form a phase-separated structure via polymerization-induced microphase separation by varying the scanning speed and using macro-reversible addition/fragmentation chain transfer (macro-RAFT) agents with different average molar masses, along with multiarmed macro-RAFT agents; such structures were used to fabricate 3D-printed parts. Various phase-separated morphologies including sea-island and reverse sea-island were achieved by controlling the laser scanning speed and RAFT type. Heterogeneous structures with different material properties were also achieved by simply changing the laser scanning speed. As the deformation due to shrinkage in the process of cleaning 3D-printed parts depends on the laser scanning speed, shape correction was introduced to suppress the effect of shrinkage and obtain the desired shape. Full article
(This article belongs to the Special Issue Polymer Micro/Nanofabrication and Manufacturing II)
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12 pages, 3575 KiB  
Article
Influence of the Heat Transfer Process on the Electrical and Mechanical Properties of Flexible Silver Conductors on Textiles
by Tomasz Raczyński, Daniel Janczak, Jerzy Szałapak, Sandra Lepak-Kuc, Dominik Baraniecki, Maria Muszyńska, Aleksandra Kądziela, Katarzyna Wójkowska, Jakub Krzemiński and Małgorzata Jakubowska
Polymers 2023, 15(13), 2892; https://doi.org/10.3390/polym15132892 - 29 Jun 2023
Viewed by 1045
Abstract
With the increase in the popularity of wearable and integrated electronics, a proper way to manufacture electronics on textiles is needed. This study aims to analyze the effect of different parameters of the heat transfer process on the electrical and mechanical properties of [...] Read more.
With the increase in the popularity of wearable and integrated electronics, a proper way to manufacture electronics on textiles is needed. This study aims to analyze the effect of different parameters of the heat transfer process on the electrical and mechanical properties of flexible electronics made on textiles, presenting it as a viable method of producing such electronics. Wires made from different composites based on silver microparticles and an insulating layer were screen-printed on a release film. Then, they were transferred onto a polyester cloth using heat transfer with different parameters. Research showed that different heat transfer parameters could influence the electrical properties of screen-printed wires, changing their resistance between −15% and +150%, making it imperative to adjust those properties depending on the materials used. Changes in the settings of heat transfer also influence mechanical properties, increasing adhesion between layers at higher temperatures. This study shows the importance of tailoring heat transfer properties and the differences that these properties make. Full article
(This article belongs to the Special Issue Polymer Micro/Nanofabrication and Manufacturing II)
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11 pages, 2193 KiB  
Article
Additive Manufactured Strain Sensor Using Stereolithography Method with Photopolymer Material
by Ishak Ertugrul, Osman Ulkir, Sezgin Ersoy and Minvydas Ragulskis
Polymers 2023, 15(4), 991; https://doi.org/10.3390/polym15040991 - 16 Feb 2023
Cited by 10 | Viewed by 2527
Abstract
As a result of the developments in additive manufacturing (AM) technology, 3D printing is transforming from a method used only in rapid prototyping to a technique used to produce large-scale equipment. This study presents the fabrication and experimental studies of a 3D-printed strain [...] Read more.
As a result of the developments in additive manufacturing (AM) technology, 3D printing is transforming from a method used only in rapid prototyping to a technique used to produce large-scale equipment. This study presents the fabrication and experimental studies of a 3D-printed strain sensor that can be used directly in soft applications. Photopolymer-based conductive and flexible ultraviolet (UV) resin materials are used in the fabrication of the sensor. A Stereolithography (SLA)-based printer is preferred for 3D fabrication. The bottom base of the sensor, which consists of two parts, is produced from flexible UV resin, while the channels that should be conductive are produced from conductive UV resin. In total, a strain sensor with a thickness of 2 mm was produced. Experimental studies were carried out under loading and unloading conditions to observe the hysteresis effect of the sensor. The results showed a close linear relationship between the strain sensor and the measured resistance value. In addition, tensile test specimens were produced to observe the behavior of conductive and non-conductive materials. The tensile strength values obtained from the test results will provide information about the sensor placement. In addition, the flexible structure of the strain sensor will ensure its usability in many soft applications. Full article
(This article belongs to the Special Issue Polymer Micro/Nanofabrication and Manufacturing II)
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14 pages, 3252 KiB  
Article
Collagen Fibril Diameter Distribution of Sheep Anterior Cruciate Ligament
by Smail Smatov, Fariza Mukasheva and Cevat Erisken
Polymers 2023, 15(3), 752; https://doi.org/10.3390/polym15030752 - 1 Feb 2023
Cited by 5 | Viewed by 1804
Abstract
The anterior cruciate ligament (ACL) tissue is a soft tissue connecting the femur and tibia at the knee joint and demonstrates a limited capacity for self-regeneration due to its low vascularity. The currently available clinical procedures are unable to fully restore damaged ACL [...] Read more.
The anterior cruciate ligament (ACL) tissue is a soft tissue connecting the femur and tibia at the knee joint and demonstrates a limited capacity for self-regeneration due to its low vascularity. The currently available clinical procedures are unable to fully restore damaged ACL tissue, and tissue engineering can offer options with a potential of restoring the torn/ruptured ACL by using biomimetic constructs that are similar to native tissue in terms of structure, composition, and functions. However, a model substrate to understand how the ACL cells regenerate the injured tissue is still not available. In this study, it is hypothesized that the nanofiber-based model substrate with bimodal and unimodal fiber diameter distributions will mimic the diameter distribution of collagen fibrils seen in healthy and injured sheep ACL, respectively. The aims were to (i) create an ACL injury in a sheep ACL by applying extensional force to rupture the healthy ACL tissue, (ii) measure the collagen fibril diameter distributions of healthy and injured ACL, (iii) fabricate polycaprolactone (PCL) nanofiber-based model constructs using electrospinning with diameter distributions similar to healthy and injured ACL tissue, and (iv) measure mechanical properties of ACL tissue and PCL electrospun constructs. The results showed that the fiber diameter distributions of PCL electrospun constructs and those of the healthy and injured ACL tissues were similar. The novelty in this investigation is that the collagen fibril diameter distribution of healthy and injured sheep ACL tissues was reported for the first time. The study is significant because it aims to create a model construct to solve an important orthopedic-related clinical problem affecting millions of people globally. The model construct fabricated in this work is expected to have an important impact on ACL regeneration efforts. Full article
(This article belongs to the Special Issue Polymer Micro/Nanofabrication and Manufacturing II)
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14 pages, 6148 KiB  
Article
Fabrication of Flexible Wiring with Intrinsically Conducting Polymers Using Blue-Laser Microstereolithography
by Mai Takenouchi, Masaru Mukai, Taichi Furukawa and Shoji Maruo
Polymers 2022, 14(22), 4949; https://doi.org/10.3390/polym14224949 - 16 Nov 2022
Cited by 7 | Viewed by 2533
Abstract
Recently, flexible devices using intrinsically conductive polymers, particularly poly(3,4-ethylenedioxythiophene) (PEDOT), have been extensively investigated. However, most flexible wiring fabrication methods using PEDOT are limited to two-dimensional (2D) fabrication. In this study, we fabricated three-dimensional (3D) wiring using the highly precise 3D printing method [...] Read more.
Recently, flexible devices using intrinsically conductive polymers, particularly poly(3,4-ethylenedioxythiophene) (PEDOT), have been extensively investigated. However, most flexible wiring fabrication methods using PEDOT are limited to two-dimensional (2D) fabrication. In this study, we fabricated three-dimensional (3D) wiring using the highly precise 3D printing method of stereolithography. Although several PEDOT fabrication methods using 3D printing systems have been studied, few have simultaneously achieved both high conductivity and precise accuracy. In this study, we review the post-fabrication process, particularly the doping agent. Consequently, we successfully fabricated wiring with a conductivity of 16 S cm−1. Furthermore, flexible wiring was demonstrated by modeling the fabricated wiring on a polyimide film with surface treatment and creating a three-dimensional fabrication object. Full article
(This article belongs to the Special Issue Polymer Micro/Nanofabrication and Manufacturing II)
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11 pages, 3115 KiB  
Article
Experimental Study of Injection Molding Replicability for the Micro Embossment of the Ultrasonic Vibrator
by Tieli Zhu, Ying Liu, Tongmin Yu, Yifei Jin and Danyang Zhao
Polymers 2022, 14(22), 4798; https://doi.org/10.3390/polym14224798 - 8 Nov 2022
Cited by 1 | Viewed by 1447
Abstract
It is challenging to fabricate micro features on an injection-molded polymer product. Ultrasonic vibration induced into micro-injection molding is helpful for flow of polymer melt. In this paper, a micro-injection mold integrated with ultrasonic vibration was designed and fabricated, and micro embossment was [...] Read more.
It is challenging to fabricate micro features on an injection-molded polymer product. Ultrasonic vibration induced into micro-injection molding is helpful for flow of polymer melt. In this paper, a micro-injection mold integrated with ultrasonic vibration was designed and fabricated, and micro embossment was machined on the surface of the ultrasonic vibrator. Poly(methacrylic acid methyl ester) (PMMA) was used for injection molding experiments, with four ultrasonic power levels (0, 300, 600, and 900 W), three injection speed levels (60, 80, and 100 cm3/s), two injection pressure levels (60 and 90 MPa) and a mold temperature of 60 °C. It was found that ultrasonic vibration perpendicular to the middle surface of the cavity is beneficial in forming transverse microstructure, but is not conducive to generating longitudinal microstructure. Increase in injection pressure can improve molding qualities for both the longitudinal micro groove and the transverse micro groove. Increase in injection speed is not conducive to forming the longitudinal micro groove but benefits formation of the transverse micro groove. When ultrasonic vibration is applied at the injection and packing stages, molding quality of the longitudinal micro groove becomes worse, while that of the transverse micro groove becomes better. Full article
(This article belongs to the Special Issue Polymer Micro/Nanofabrication and Manufacturing II)
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