Rapid prototyping and facile customization of conductive hydrogel bioelectronics based on all laser process.

Proper customization in size and shape is essential in implantable bioelectronics for stable bio-signal recording. Over the past decades, many researchers have heavily relied on conventional photolithography processes to fabricate implantable bioelectronics. Therefore, they could not avoid the critical limitation of high cost and complex processing steps to optimize bioelectronic devices for target organs with various sizes and shapes. Here, we propose rapid prototyping using all laser processes to fabricate customized bioelectronics. PEDOT:PSS is selectively irradiated by an ultraviolet (UV) pulse laser to form wet-stable conductive hydrogels that can softly interact with biological tissues (50 µm line width). The encapsulation layer is selectively patterned using the same laser source by UV-curing polymer networks (110 µm line width). For high stretchability (over 100%), mesh structures are made by the selective laser cutting process. Our rapid prototyping strategy minimizes the use of high-cost equipment, using only a single UV laser source to process the electrodes, encapsulation, and substrates that constitute bioelectronics without a photomask, enabling the prototyping stretchable microelectrode array with an area of 1 cm2 less than 10 min. We fabricated an optimized stretchable microelectrode array with low impedances (∼1.1 kΩ at 1 kHz) that can effectively record rat's cardiac signals with various health states.

The Roles of Microprobe in Localized Electrodeposition: Electrolyte Localized Transport and Force-Displacement Sensitivity.

Facing the rapid development of 6G communication, long-wave infrared metasurface and biomimetic microfluidics, the performance requirements for microsystems based on metal tiny structures are gradually increasing. As one of powerful methods for fabrication metal complex microstructures, localized electrochemical deposition microadditive manufacturing technology can fabricate copper metal micro overhanging structures without masks and supporting materials. In this study, the role of the microprobe cantilever (MC) in localized electrodeposition was studied. The MC can be used for precise deposition with electrolyte localized transport function and high accuracy force-displacement sensitivity. To prove this, the electrolyte flow was simulated when the MC was in bending or normal state. The simulation results can indicate the influence of turbulent flow on the electrolyte flow velocity and the pressure at the end of the pyramid. The results show that the internal flow velocity increased by 8.9% in the bending probe as compared with normal. Besides, this study analyzed the force-potential sensitivity characteristics of the MC. Using the deformation of the MC as an intermediate variable, the model of the probe tip displacement caused by the growth of the deposit and the voltage value displayed by the photodetector was mathematically established. In addition, the deposition of a single voxel was simulated by simulation process with the simulated height of 520 nm for one voxel, and the coincidence of simulation and experimental results was 93.1%. In conclusion, this method provides a new way for localized electrodeposition of complex microstructures.

Surface Finishing and Coating Parameters Impact on Additively Manufactured Binder-Jetted Steel-Bronze Composites.

In this paper, electroless nickel plating is explored for the protection of binder-jetting-based additively manufactured (AM) composite materials. Electroless nickel plating was attempted on binder-jetted composites composed of stainless steel and bronze, resulting in differences in the physicochemical properties. We investigated the impact of surface finishing, plating solution chemistry, and plating parameters to attain a wide range of surface morphologies and roughness levels. We employed the Keyence microscope to quantitatively evaluate dramatically different surface properties before and after the coating of AM composites. Scanning electron microscopy revealed a wide range of microstructural properties in relation to each combination of surface finishing and coating parameters. We studied chempolishing, plasma cleaning, and organic cleaning as the surface preparation methods prior to coating. We found that surface preparation dictated the surface roughness. Taguchi statistical analysis was performed to investigate the relative strength of experimental factors and interconnectedness among process parameters to attain optimum coating qualities. The quantitative impacts of phosphorous level, temperature, surface preparation, and time factor on the roughness of the nickel-plated surface were 17.95%, 8.2%, 50.02%, and 13.21%, respectively. On the other hand, the quantitative impacts of phosphorous level, temperature, surface preparation, and time factor on the thickness of nickel plating were 35.12%, 41.40%, 3.87%, and 18.24%, respectively. The optimum combination of the factors' level projected the lowest roughness of Ra at 7.76 µm. The optimum combination of the factors' level projected the maximum achievable thickness of ~149 µm. This paper provides insights into coating process for overcoming the sensitivity of AM composites in hazardous application spaces via robust coating.

Spatial Trueness Evaluation of 3D-Printed Dental Model Made of Photopolymer Resin: Use of Special Structurized Dental Model.

(1) Background: Various 3D printers are available for dental practice; however, a comprehensive accuracy evaluation method to effectively guide practitioners is lacking. This in vitro study aimed to propose an optimized method to evaluate the spatial trueness of a 3D-printed dental model made of photopolymer resin based on a special structurized dental model, and provide the preliminary evaluation results of six 3D printers. (2) Methods: A structurized dental model comprising several geometrical configurations was designed based on dental crown and arch measurement data reported in previous studies. Ninety-six feature sizes can be directly measured on this original model with minimized manual measurement errors. Six types of photo-curing 3D printers, including Objet30 Pro using the Polyjet technique, Projet 3510 HD Plus using the Multijet technique, Perfactory DDP and DLP 800d using the DLP technique, Form2 and Form3 using the SLA technique, and each printer's respective 3D-printable dental model materials, were used to fabricate one set of physical models each. Regarding the feature sizes of the simulated dental crowns and dental arches, linear measurements were recorded. The scanned digital models were compared with the design data, and 3D form errors (including overall 3D deviation; flatness, parallelism, and perpendicularity errors) were measured. (3) Results: The lowest overall 3D deviation, flatness, parallelism, and perpendicularity errors were noted for the models printed using the Objet30 Pro (overall value: 45 µm), Form3 (0.061 ± 0.019 mm), Objet30 Pro (0.138 ± 0.068°), and Projet 3510 HD Plus (0.095 ± 0.070°), respectively. In color difference maps, different deformation patterns were observed in the printed models. The feature size proved most accurate for the Objet30 Pro fabricated models (occlusal plane error: 0.02 ± 0.36%, occlusogingival direction error: -0.06 ± 0.09%). (4) Conclusions: The authors investigated a novel evaluation approach for the spatial trueness of a 3D-printed dental model made of photopolymer resin based on a structurized dental model. This method can objectively and comprehensively evaluate the spatial trueness of 3D-printed dental models and has a good repeatability and generalizability.

Trueness of five different 3D printing systems including budget- and professional-grade printers: An In vitro study.

Problem: Several types of 3D printers with different techniques and prices are available on the market. However, results in the literature are inconsistent, and there is no comprehensive agreement on the accuracy of 3D printers of different price categories for dental applications. Aim: This study aimed to investigate the accuracy of five different 3D printing systems, including a comparison of budget- and higher-end 3D printing systems, according to a standardized production and evaluation protocol. Material and methods: A maxillary reference model with prepared teeth was created using 16 half-ball markers with a diameter of 1 mm to facilitate measurements. A reference file was fabricated using five different 3D printers. The printed models were scanned and superimposed onto the original standard tesselation language (.stl) file, and digital measurements were performed to assess the 3-dimensional and linear deviations between the reference and test models. Results: After examining the entire surface of the models, we found that 3D printers using Fused filament fabrication (FFF) technology -120.2 (20.3) µm create models with high trueness but high distortion. Distortions along the z-axis were found to be the highest with the stereolithography (SLA)-type 3D printer at -153.7 (38.7) µm. For the 4-unit FPD, we found 201.9 (41.8) µm deviation with the digital light processing (DLP) printer. The largest deviation (-265.1 (55.4) µm) between the second molars was observed for the DLP printer. Between the incisor and the second molar, the best results were produced by the FFF printer with -30.5 (76.7) µm. Conclusion: Budget-friendly 3D printers are comparable to professional-grade printers in terms of precision. In general, the cost of a printing system is not a reliable indicator of its level of accuracy.

Exploring the frontier of rapid prototyping technologies for plant synthetic biology and what could lie beyond.

Realizing the full potential of plant synthetic biology both to elucidate the relationship between genotype and phenotype and to apply these insights to engineer traits requires rapidly iterating through design-build-test cycles. However, the months-long process of transgenesis, the long generation times, and the size-based limitations on experimentation have stymied progress by limiting the speed and scale of these cycles. Herein, we review a representative sample of recent studies that demonstrate a variety of rapid prototyping technologies that overcome some of these bottlenecks and accelerate progress. However, each of them has caveats that limit their broad utility. Their complementary strengths and weaknesses point to the intriguing possibility that these strategies could be combined in the future to enable rapid and scalable deployment of synthetic biology in plants.

3D Printed Materials for Permanent Restorations in Indirect Restorative and Prosthetic Dentistry: A Critical Review of the Literature.

The objective of this study was to review the scientific evidence currently available on 3D printable materials and 3D printing technologies used for the fabrication of permanent restorations, focusing on material properties that are clinically relevant. A literature search was performed on four databases (MEDLINE/PubMed, Scopus, Cochrane Library, Web of Science) for articles published from January 2013 until November 2023, using a combination of free words: (restorative dentistry OR prosthetic dentistry) AND (3D printing OR additive manufacturing OR rapid prototyping) AND materials. Two reviewers screened titles and/or abstracts of 2.468 unique studies. In total, 83 studies were selected for full-text reading, from which 36 were included in the review. The assessed variables were mechanical properties, reporting in most of the cases positive results, dimensional accuracy and fit, reporting conflicting results with a predominance of positive, aesthetic properties, with positive reports but scarcely addressed, and biological properties, almost unexplored in independent studies. Despite numerous studies with positive results in favor, papers with negative outcomes were also retrieved. Aesthetic and biological properties are conversely still mostly unexplored. There remains a lack of conclusive evidence for viable 3D printable restorative and prosthodontic materials for permanent restorations. Research should be strengthened by defining international standards for laboratory testing and, where pre-clinical data are promising, conducting clinical trials.

Three-dimensional printed models can reduce costs and surgical time for complex proximal humeral fractures: preoperative planning, patient satisfaction, and improved resident skills.

BACKGROUND: Proximal humeral fractures (PHFs) are still controversial with regards to treatment and are difficult to classify. The study's objective is to show that preoperative planning performed while handling a three-dimensional (3D) printed anatomical model of the fracture can ensure a better understanding of trauma for both surgeons and patients. MATERIALS AND METHODS: Twenty patients (group A, cases) with complex PHF were evaluated preoperatively by reproducing life-size, full-touch 3D anatomical models. Intraoperative blood loss, radiographic controls, duration of surgery, and clinical outcomes of patients in group A were compared with 20 patients (group B, controls) who underwent standard preoperative evaluation. Additionally, senior surgeons and residents, as well as group A patients, answered a questionnaire to evaluate innovative preoperative planning and patient compliance. Cost analysis was evaluated. RESULTS: Intraoperative radiography controls and length of operation were significantly shorter in group A. There were no differences in clinical outcomes or blood loss. Patients claim a better understanding of the trauma suffered and the proposed treatment. Surgeons assert that the planning of the definitive operation with 3D models has had a good impact. The development of this tool has been well received by the residents. The surgery was reduced in length by 15%, resulting in savings of about EUR 400 for each intervention. CONCLUSIONS: Fewer intraoperative radiography checks, shorter surgeries, and better patient compliance reduce radiation exposure for patients and healthcare staff, enhance surgical outcomes while reducing expenses, and lower the risk of medicolegal claims. LEVEL OF EVIDENCE: Level I, prospective randomized case-control study.

Application of 3D printing in early phase development of pharmaceutical solid dosage forms.

Three-dimensional printing (3DP) is an emerging technology, offering the possibility for the development of dose-customized, effective, and safe solid oral dosage forms (SODFs). Although 3DP has great potential, it does come with certain limitations, and the traditional drug manufacturing platforms remain the industry standard. The consensus appears to be that 3DP technology is expected to benefit personalized medicine the most, but that it is unlikely to replace conventional manufacturing for mass production. The 3DP method, on the other hand, could prove well-suited for producing small batches as an adaptive manufacturing technique for enabling adaptive clinical trial design for early clinical studies. The purpose of this review is to discuss recent advancements in 3DP technologies for SODFs and to focus on the applications for SODFs in the early clinical development stages, including a discussion of current regulatory challenges and quality controls.

Reduced graphene oxide-reinforced tricalcium phosphate/gelatin/chitosan light-responsive scaffolds for application in bone regeneration.

Bone is a mineralized tissue with the intrinsic capacity for constant remodeling. Rapid prototyping techniques, using biomaterials that mimic the bone native matrix, have been used to develop osteoinductive and osteogenic personalized 3D structures, which can be further combined with drug delivery and phototherapy. Herein, a Fab@Home 3D Plotter printer was used to promote the layer-by-layer deposition of a composite mixture of gelatin, chitosan, tricalcium phosphate, and reduced graphene oxide (rGO). The phototherapeutic potential of the new NIR-responsive 3D_rGO scaffolds was assessed by comparing scaffolds with different rGO concentrations (1, 2, and 4 mg/mL). The data obtained show that the rGO incorporation confers to the scaffolds the capacity to interact with NIR light and induce a hyperthermy effect, with a maximum temperature increase of 16.7 °C after under NIR irradiation (10 min). Also, the increase in the rGO content improved the hydrophilicity and mechanical resistance of the scaffolds, particularly in the 3D_rGO4. Furthermore, the rGO could confer an NIR-triggered antibacterial effect to the 3D scaffolds, without compromising the osteoblasts' proliferation and viability. In general, the obtained data support the development of 3D_rGO for being applied as temporary scaffolds supporting the new bone tissue formation and avoiding the establishment of bacterial infections.

Modular training model for education of students in restorative and prosthodontic dentistry.

INTRODUCTION: At the moment, no commercial model solution is available for the individualisation of the dentition depending on the clinical case scenario. Furthermore, the realistic training of most restorative and prosthodontic procedures on a single dental study model is not possible. The aim of this study was the creation of a new training model to fill this gap. MATERIALS AND METHODS: Complete upper and lower jaw models were created based on existing scans and radiological data from a patient. All components for 100 complete models and 1128 teeth for the training were produced with a SLA-printer. Overall, 94 voluntary students attending the first and second preclinical course in prosthodontics tested the functionality of the model with three different tooth types against a standard dental study model and real teeth. After the training, the model was rated in a questionnaire. RESULTS: The production of the models and teeth was feasible. The overall rating of the different teeth was worse for type I (Ø 3.6 ± 1.1), significantly better for type II (Ø 2.5 ± 1.0) and type III (Ø 2.4 ± 1.0) than a standard typodont tooth (Ø 2.7 ± 1.1). The new model was rated significantly better overall (Ø 2.6 ± 1.0) than the standard training model (Ø 3.0 ± 1.1). CONCLUSIONS: The aim of this study was fulfilled. A superior training model was created with equivalent and better tooth types. The new teeth were outstanding in terms of cost-efficiency, appearance and feeling during preparation.

Practical applications of three-dimensional printing for process improvement in the cytopathology laboratory.

With the increased availability of three-dimensional (3D) printers, innovative teaching and training materials have been created in medical fields. For pathology, the use of 3D printing has been largely limited to anatomic representations of disease processes or the development of supplies during the coronavirus disease 2019 pandemic. Herein, an institution's 3D printing laboratory and staff with expertise in additive manufacturing illustrate how this can address design issues in cytopathology specimen collection and processing. The authors' institutional 3D printing laboratory, along with students and trainees, used computer-aided design and 3D printers to iterate on design, create prototypes, and generate final usable materials using additive manufacturing. The program Microsoft Forms was used to solicit qualitative and quantitative feedback. The 3D-printed models were created to assist with cytopreparation, rapid on-site evaluation, and storage of materials in the preanalytical phase of processing. These parts provided better organization of materials for cytology specimen collection and staining, in addition to optimizing storage of specimens with multiple sized containers to optimize patient safety. The apparatus also allowed liquids to be stabilized in transport and removed faster at the time of rapid on-site evaluation. Rectangular boxes were also created to optimally organize all components of a specimen in cytopreparation to simplify and expedite the processes of accessioning and processing, which can minimize errors. These practical applications of 3D printing in the cytopathology laboratory demonstrate the utility of the design and printing process on improving aspects of the workflow in cytopathology laboratories to maximize efficiency, organization, and patient safety.

Zirconia Implants Produced by Additive Manufacturing - A Scoping Review.

INTRODUCTION: Additive manufacturing is a tool with potential use in medicine and dentistry. The manufacture of metals and composites is already advanced, however, concerns about titanium hypersensitivity, tissue staining, and corrosion caused by gradual material degradation encourage research into more biocompatible alternatives. OBJECTIVE: This systematic scoping review aimed to gather studies that evaluated zirconia implants produced by additive manufacturing to describe the current stage of the printing technique and the final product. METHODS: Searches in Embase, PubMed, SCOPUS, Web of Science, and Google Scholar databases were enriched with manual searches between February and March 2021 and updated in June 2022 using keywords: zirconium implants, zirconium oxide, additive manufacturing, rapid prototyping, 3D printing, selective laser melting, and electron beam melting. The criteria included studies that evaluated or described zirconia implants obtained by 3D printing, with a direct relationship to dentistry or orthopedics. RESULTS: The database search resulted in 671 articles. Eight articles were selected for full reading and remained in this systematic review. CONCLUSION: The printing technique for zirconia implants is promising. However, further studies are required before implants produced by the printing technique can be tested clinically. The literature with results regarding the impression product is still limited.

The Utility of 3D Printing for Surgical Planning and Patient-Specific Implant Design in Maxillofacial Surgery: A Narrative Review.

Maxillofacial reconstructive implants are typically created in standard shapes and have a widespread application in head and neck surgery. During surgical procedures, the implant must be correctly bent according to the architecture of the particular bones. Bending takes practice, especially for untrained surgeons. Furthermore, repeated bending may increase internal stress, resulting in fatigue in vivo under masticatory loading and an array of consequences, including implant failure. There is a risk of fracture, screw loosening, and bone resorption. Resorption, infection, and displacement are usually associated with the use of premade alloplastic implants and autogenous grafts. Recent technological breakthroughs have led to the use of patient-specific implants (PSIs) developed by computer-designed additive manufacturing in reconstructive surgery. The use of computer-designed three-dimensional (3D)-printed PSI allows for more precise restoration of maxillofacial deformities, avoiding the common difficulties associated with premade implants and increasing patient satisfaction. Additive manufacturing is something that refers to a group of additive manufacturing methods. This technique has been quickly used in a variety of surgical procedures. The exponential expansion of this technology can be attributed to its enormous surgical value. Adding 3D printing to a medical practice can be a rewarding experience with stunning results.

A Rapid Prototyping Approach for Multi-Material, Reversibly Sealed Microfluidics.

Microfluidic organ-on-chip models recapitulate increasingly complex physiological phenomena to study tissue development and disease mechanisms, where there is a growing interest in retrieving delicate biological structures from these devices for downstream analysis. Standard bonding techniques, however, often utilize irreversible sealing, making sample retrieval unfeasible or necessitating destructive methods for disassembly. To address this, several commercial devices employ reversible sealing techniques, though integrating these techniques into early-stage prototyping workflows is often ignored because of the variation and complexity of microfluidic designs. Here, we demonstrate the concerted use of rapid prototyping techniques, including 3D printing and laser cutting, to produce multi-material microfluidic devices that can be reversibly sealed. This is enhanced via the incorporation of acrylic components directly into polydimethylsiloxane channel layers to enhance stability, sealing, and handling. These acrylic components act as a rigid surface separating the multiple mechanical seals created between the bottom substrate, the microfluidic features in the device, and the fluidic interconnect to external tubing, allowing for greater design flexibility. We demonstrate that these devices can be produced reproducibly outside of a cleanroom environment and that they can withstand ~1 bar pressures that are appropriate for a wide range of biological applications. By presenting an accessible and low-cost method, we hope to enable microfluidic prototyping for a broad range of biomedical research applications.

Expanding flavone and flavonol production capabilities in Escherichia coli.

Flavones and flavonols are important classes of flavonoids with nutraceutical and pharmacological value, and their production by fermentation with recombinant microorganisms promises to be a scalable and economically favorable alternative to extraction from plant sources. Flavones and flavonols have been produced recombinantly in a number of microorganisms, with Saccharomyces cerevisiae typically being a preferred production host for these compounds due to higher yields and titers of precursor compounds, as well as generally improved ability to functionally express cytochrome P450 enzymes without requiring modification to improve their solubility. Recently, a rapid prototyping platform has been developed for high-value compounds in E. coli, and a number of gatekeeper (2S)-flavanones, from which flavones and flavonols can be derived, have been produced to high titers in E. coli using this platform. In this study, we extended these metabolic pathways using the previously reported platform to produce apigenin, chrysin, luteolin and kaempferol from the gatekeeper flavonoids naringenin, pinocembrin and eriodictyol by the expression of either type-I flavone synthases (FNS-I) or type-II flavone synthases (FNS-II) for flavone biosynthesis, and by the expression of flavanone 3-dioxygenases (F3H) and flavonol synthases (FLS) for the production of the flavonol kaempferol. In our best-performing strains, titers of apigenin and kaempferol reached 128 mg L-1 and 151 mg L-1 in 96-DeepWell plates in cultures supplemented with an additional 3 mM tyrosine, though titers for chrysin (6.8 mg L-1) from phenylalanine, and luteolin (5.0 mg L-1) from caffeic acid were considerably lower. In strains with upregulated tyrosine production, apigenin and kaempferol titers reached 80.2 mg L-1 and 42.4 mg L-1 respectively, without the further supplementation of tyrosine beyond the amount present in the rich medium. Notably, the highest apigenin, chrysin and luteolin titers were achieved with FNS-II enzymes, suggesting that cytochrome P450s can show competitive performance compared with non-cytochrome P450 enzymes in prokaryotes for the production of flavones.

Clinical situations for which 3D Printing is considered an appropriate representation or extension of data contained in a medical imaging examination: vascular conditions.

BACKGROUND: Medical three-dimensional (3D) printing has demonstrated utility and value in anatomic models for vascular conditions. A writing group composed of the Radiological Society of North America (RSNA) Special Interest Group on 3D Printing (3DPSIG) provides appropriateness recommendations for vascular 3D printing indications. METHODS: A structured literature search was conducted to identify all relevant articles using 3D printing technology associated with vascular indications. Each study was vetted by the authors and strength of evidence was assessed according to published appropriateness ratings. RESULTS: Evidence-based recommendations for when 3D printing is appropriate are provided for the following areas: aneurysm, dissection, extremity vascular disease, other arterial diseases, acute venous thromboembolic disease, venous disorders, lymphedema, congenital vascular malformations, vascular trauma, vascular tumors, visceral vasculature for surgical planning, dialysis access, vascular research/development and modeling, and other vasculopathy. Recommendations are provided in accordance with strength of evidence of publications corresponding to each vascular condition combined with expert opinion from members of the 3DPSIG. CONCLUSION: This consensus appropriateness ratings document, created by the members of the 3DPSIG, provides an updated reference for clinical standards of 3D printing for the care of patients with vascular conditions.

Rapid IoT Prototyping: A Visual Programming Tool and Hardware Solutions for LoRa-Based Devices.

LoRa technology has gained popularity as one of the most widely used standards for device interconnection due to its ability to cover long distances and energy efficiency, making it a suitable choice for various Internet of Things (IoT) monitoring and control applications. In this sense, this work presents the development of a visual support tool for creating IoT devices with LoRa and LoRaWAN connectivity. This work significantly advances the state of the art in LoRa technology by introducing a novel visual support tool tailored for creating IoT devices with LoRa and LoRaWAN connectivity. By simplifying the development process and offering compatibility with multiple hardware solutions, this research not only facilitates the integration of LoRaWAN technology within educational settings but also paves the way for rapid prototyping of IoT nodes. The incorporation of block programming for LoRa and LoRaWAN using the Arduinoblocks framework as a graphical environment enhances the capabilities of the tool, positioning it as a comprehensive solution for efficient firmware generation. In addition to the visual tool for firmware generation, multiple compatible hardware solutions enable easy, economical, and stable development, offering a comprehensive hardware and software solution. The hardware proposal is based on an ESP32 microcontroller, known for its power and low cost, in conjunction with an RFM9x module that is based on SX127x LoRa transceivers. Finally, three successfully tested use cases and a discussion are presented.

Low-temperature deposition manufacturing technology: a novel 3D printing method for bone scaffolds.

The application of three-dimensional printing technology in the medical field has great potential for bone defect repair, especially personalized and biological repair. As a green manufacturing process that does not involve liquefication through heating, low-temperature deposition manufacturing (LDM) is a promising type of rapid prototyping manufacturing and has been widely used to fabricate scaffolds in bone tissue engineering. The scaffolds fabricated by LDM have a multi-scale controllable pore structure and interconnected micropores, which are beneficial for the repair of bone defects. At the same time, different types of cells or bioactive factor can be integrated into three-dimensional structural scaffolds through LDM. Herein, we introduced LDM technology and summarize its applications in bone tissue engineering. We divide the scaffolds into four categories according to the skeleton materials and discuss the performance and limitations of the scaffolds. The ideas presented in this review have prospects in the development and application of LDM scaffolds.

Rapid Micromolding of Sub-100 µm Microfluidic Channels Using an 8K Stereolithographic Resin 3D Printer.

Engineering microfluidic devices relies on the ability to manufacture sub-100 micrometer fluidic channels. Conventional lithographic methods provide high resolution but require costly exposure tools and outsourcing of masks, which extends the turnaround time to several days. The desire to accelerate design/test cycles has motivated the rapid prototyping of microfluidic channels; however, many of these methods (e.g., laser cutters, craft cutters, fused deposition modeling) have feature sizes of several hundred microns or more. In this paper, we describe a 1-day process for fabricating sub-100 µm channels, leveraging a low-cost (USD 600) 8K digital light projection (DLP) 3D resin printer. The soft lithography process includes mold printing, post-treatment, and casting polydimethylsiloxane (PDMS) elastomer. The process can produce microchannels with 44 µm lateral resolution and 25 µm height, posts as small as 400 µm, aspect ratio up to 7, structures with varying z-height, integrated reservoirs for fluidic connections, and a built-in tray for casting. We discuss strategies to obtain reliable structures, prevent mold warpage, facilitate curing and removal of PDMS during molding, and recycle the solvents used in the process. To our knowledge, this is the first low-cost 3D printer that prints extruded structures that can mold sub-100 µm channels, providing a balance between resolution, turnaround time, and cost (~USD 5 for a 2 × 5 × 0.5 cm3 chip) that will be attractive for many microfluidics labs.