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A major goal of PDMS microfabrication is to develop a simple and inexpensive method for rapid fabrication. Despite the recent advancements in this field, facile PDMS microfabrication on non-planar surfaces remains elusive. Here we report a facile method for rapid prototyping of PDMS microdevices via µPLAT (microscale plasma-activated templating) on non-planar surfaces through micropatterning of hydrophilic/hydrophobic interface by flexible PVC hollow-out mask. This mask can be easily prepared with flexible PVC film through a cutting crafter and applied as pattern definer during the plasma treatment for microscale hydrophilic/hydrophobic interface formation on different substrates. The whole process requires low inputs in terms of time as well as toxic chemicals. Inspired by liquid molding, we demonstrated its use for rapid prototyping of PDMS microstructures. Following the proof-of-concept study, we also demonstrated the use of the flexible hollow-out mask to facilitate cell patterning on curved substrates, which is difficult to realize with conventional methods. Collectively, our work utilizes flexible and foldable PVC film as mask materials for facile microscale hydrophilic non-planar surface modification to establish a useful tool for PDMS prototyping and cell patterning.
(© 2020 IOP Publishing Ltd.)

Introduction: Rapid prototyping is a process by which threedimensional (3D) computerized surface models are converted into physical models. In this study, a 3D heart bio model was created using the rapid prototyping method and the accuracy of this heart model was assessed by clinicians.
Methods: The two-dimensional images of normal heart from gated computed tomography scan datasets were used to create a 3D model of the heart. The slices were then processed using the software BioModroid and printed with the 3D printer. The evaluation of the model was performed by a questionnaire answered by four cardiothoracic surgeons, 12 cardiologists, five radiologists, and nine surgical registrars.
Results: Eighty-six percent of the anatomy structures showed in this model scored 100% accuracy. Structures such as circumflex branch of left coronary artery, great cardiac vein, papillary muscle, and coronary sinus were each rated 77%, 70%, 70%, and 57% accurate. Among 30 clinicians, a total of 93% rated the model accuracy as good and above; 64% of the clinicians evaluated this model as an excellent teaching tool for anatomy class. As a visual aid for surgery or interventional procedures, the model was rated excellent (40%), good (50%), average (23%), and poor (3%); 70% of the clinicians scored the model as above average for training purpose. Overall, this 3D rapid prototyping cardiac model was rated as excellent (33%), good (50%), and average (17%).
Conclusion: This 3D rapid prototyping heart model will be a valuable source of anatomical education and cardiac interventional management.

Gas fermentation by autotrophic bacteria, such as clostridia, offers a sustainable path to numerous bioproducts from a range of local, highly abundant, waste and low-cost feedstocks, such as industrial flue gases or syngas generated from biomass or municipal waste. Unfortunately, designing and engineering clostridia remains laborious and slow. The ability to prototype individual genetic part function, gene expression patterns, and biosynthetic pathway performance in vitro before implementing designs in cells could help address these bottlenecks by speeding up design. Unfortunately, a high-yielding cell-free gene expression (CFE) system from clostridia has yet to be developed. Here, we report the development and optimization of a high-yielding (236 ± 24 μg/mL) batch CFE platform from the industrially relevant anaerobe, Clostridium autoethanogenum. A key feature of the platform is that both circular and linear DNA templates can be applied directly to the CFE reaction to program protein synthesis. We demonstrate the ability to prototype gene expression, and quantitatively map aerobic cell-free metabolism in lysates from this system. We anticipate that the C. autoethanogenum CFE platform will not only expand the protein synthesis toolkit for synthetic biology, but also serve as a platform in expediting the screening and prototyping of gene regulatory elements in non-model, industrially relevant microbes.
(Copyright © 2020 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.)

Microfluidic technologies have enormous potential to offer breakthrough solutions across a wide range of applications. However, the rate of scale-up and commercialization of these technologies has lagged significantly behind promising breakthrough developments in the lab, due at least in part to the problems presented by transitioning from benchtop fabrication methods to mass-manufacturing. In this work, we develop and validate a method to create functional microfluidic prototype devices using 3D printed masters in an industrial-scale roll-to-roll continuous casting process. There were no significant difference in mixing performance between the roll-to-roll cast devices and the PDMS controls in fluidic mixing tests. Furthermore, the casting process provided information on the suitability of the prototype microfluidic patterns for scale-up. This work represents an important step in the realization of high-volume prototyping and manufacturing of microfluidic patterns for use across a broad range of applications.

Micro total analytical systems (μTAS) are attractive to multiple fields that include chemistry, medicine and engineering due to their portability, low power usage, potential for automation, and low sample and reagent consumption, which in turn results in low waste generation. The development of fully-functional μTAS is an iterative process, based on the design, fabrication and testing of multiple prototype microdevices. Typically, microfabrication protocols require a week or more of highly-skilled personnel time in high-maintenance cleanroom facilities, which makes this iterative process cost-prohibitive in many locations worldwide. Rapid-prototyping tools, in conjunction with the use of polydimethylsiloxane (PDMS), enable rapid development of microfluidic structures at lower costs, circumventing these issues in conventional microfabrication techniques. Multiple rapid-prototyping methods to fabricate PDMS-based microfluidic devices have been demonstrated in literature since the advent of soft-lithography in 1998; each method has its unique advantages and drawbacks. Here, we present a tutorial discussing current rapid-prototyping techniques to fabricate PDMS-based microdevices, including soft-lithography, print-and-peel and scaffolding techniques, among other methods, specifically comparing resolution of the features, fabrication processes and associated costs for each technique. We also present thoughts and insights towards each step of the iterative microfabrication process, from design to testing, to improve the development of fully-functional PDMS-based microfluidic devices at faster rates and lower costs.
(Copyright © 2020 Elsevier B.V. All rights reserved.)

Self-driving cars and autonomous vehicles are revolutionizing the automotive sector, shaping the future of mobility altogether. Although the integration of novel technologies such as Artificial Intelligence (AI) and Cloud/Edge computing provides golden opportunities to improve autonomous driving applications, there is the need to modernize accordingly the whole prototyping and deployment cycle of AI components. This paper proposes a novel framework for developing so-called AI Inference Engines for autonomous driving applications based on deep learning modules, where training tasks are deployed elastically over both Cloud and Edge resources, with the purpose of reducing the required network bandwidth, as well as mitigating privacy issues. Based on our proposed data driven V-Model, we introduce a simple yet elegant solution for the AI components development cycle, where prototyping takes place in the cloud according to the Software-in-the-Loop (SiL) paradigm, while deployment and evaluation on the target ECUs (Electronic Control Units) is performed as Hardware-in-the-Loop (HiL) testing. The effectiveness of the proposed framework is demonstrated using two real-world use-cases of AI inference engines for autonomous vehicles, that is environment perception and most probable path prediction.

Metabolic engineering of microorganisms to produce sustainable chemicals has emerged as an important part of the global bioeconomy. Unfortunately, efforts to design and engineer microbial cell factories are challenging because design-build-test cycles, iterations of re-engineering organisms to test and optimize new sets of enzymes, are slow. To alleviate this challenge, we demonstrate a cell-free approach termed in vitro Prototyping and Rapid Optimization of Biosynthetic Enzymes (or iPROBE). In iPROBE, a large number of pathway combinations can be rapidly built and optimized. The key idea is to use cell-free protein synthesis (CFPS) to manufacture pathway enzymes in separate reactions that are then mixed to modularly assemble multiple, distinct biosynthetic pathways. As a model, we apply our approach to the 9-step heterologous enzyme pathway to limonene in extracts from Escherichia coli. In iterative cycles of design, we studied the impact of 54 enzyme homologs, multiple enzyme levels, and cofactor concentrations on pathway performance. In total, we screened over 150 unique sets of enzymes in 580 unique pathway conditions to increase limonene production in 24 h from 0.2 to 4.5 mM (23-610 mg/L). Finally, to demonstrate the modularity of this pathway, we also synthesized the biofuel precursors pinene and bisabolene. We anticipate that iPROBE will accelerate design-build-test cycles for metabolic engineering, enabling data-driven multiplexed cell-free methods for testing large combinations of biosynthetic enzymes to inform cellular design.
(Copyright © 2020 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.)

Powered ankle-foot prostheses for walking often have limitations in the range of motion and in push-off power, if compared to a lower limb of a healthy person. A new design of a powered ankle-foot prosthesis is proposed to obtain a wide range of motion and an adequate power for a push-off step. The design methodology for this prosthesis has three points. In the first one, a dimensionless kinematic model of the lower limb in the sagittal plane is built, through an experimental campaign with healthy subjects, to calculate the angles of lower limb during the gait. In the second point a multibody inverse dynamic model of the lower limb is constructed to calculate the foot-ground contact force, its point of application and the ankle torque too, entering as input data the calculated angles of the lower limb in the previous point. The third point requires, as input of the inverse dynamic model, the first dimensioning data of the ankle-foot prosthesis to obtain the load acting on the components of the prosthesis and the angle torque of the actuator during the gait cycle. Finally, an iteration cycle begins with the inverse dynamic model modifying the ankle torque and angle until these quantities during the gait are as close as possible to the physiological quantities. After the mechanical design and the construction of the prototype of the prosthesis, an experimental methodology was used for preliminary validation of the design. The preliminary tests in the laboratory on the prototype alone show that the range of motion of the ankle angle during the gait is close to a healthy person's: 27.6° vs. 29°. The pushing force of the distal area of the prototype is 1.000 N, instead of 1.600 N, because a budget reduction forced us to choose components for the prototype with lower performance.

The objective of this study was to evaluate a method for printing a custom radiocontrast agent mixture to develop computed tomography markers of various shapes and sizes for assisting physicians in computed tomography-guided procedures. The radiocontrast agent mixture was designed to be bright in a computed tomography image, able to be extruded from a nozzle as a liquid and transition into a solid, and sufficiently viscous to be extruded through the tip of a needle in a controlled manner. A mixture printing method was developed using a syringe to house the mixture, a syringe pump to extrude the mixture, and a computer numeric control laser cutter to direct the nozzle in the desired path. To assess the efficacy of printing the radiocontrast agent mixture, we printed several designs, collected computed tomography images, and evaluated various physical properties of the printing method and the resulting computed tomography markers. The average line thickness was 1.56 mm (standard deviation of 0.19 mm, n = 30), the infill percentage was 99.9%, and the deviation in roundness was 0.23 mm ( n = 30). These results demonstrated the ability of the proposed method to create various types of skin markers, such as dots, lines, and hollow or solid shapes. Additionally, flat printed patterns can be folded to form three-dimensional structures that can be used to guide and support needle insertions.

Introduction: Considering higher risks of candidates for cardiac regenerative therapy with compromised cardiac function, it is anticipated to develop less invasive surgical procedures. In the present study, we aimed to develop a prototype of totally endoscopic cell sheet delivery device and evaluate the surgical technique for epicardial cell sheet placement using three-dimensional (3D) printed simulators based on human computed tomography data.
Methods: We designed an endoscopic cell sheet delivery device with outer and inner frame with self-expandable applicator which can be opened in thoracic cavity. We launched spout line to provide liquids on the applicator surface and tension line to gently bend the applicator dorsally. We prepared human mesenchymal stem cell (MSC) sheets and compared wet/dry conditions of 3D printed heart/porcine heart and applicator to identify suitable conditions for cell sheet transplantation. Finally we validated the feasibility of endoscopic transplantation to anterior and lateral wall of left ventricle using 3D printed simulators.
Results: Moist condition of both 3D printed heart/porcine heart surface and applicator at transplantation yielded highest successful rate (100%, p = 0.0197). For both endoscopic transplantation sites, MSC sheets were successfully deployed. The procedure duration was 157 ± 23 s for anterior wall and 123 ± 13 s for the lateral wall in average, respectively.
Conclusions: We developed a novel prototype of endoscopic cell sheet delivery device for minimally-invasive cardiac regenerative therapy utilizing a 3D printed simulator. The commercialization of the prototype may provide a safe minimally-invasive method to deliver potential cardiac regenerative therapy in the future.
(© 2020 The Japanese Society for Regenerative Medicine. Production and hosting by Elsevier B.V.)

This paper presents a novel design of a prosthetic foot that features adaptable stiffness that changes according to the speed of ankle motion. The motivation is the natural graduation in stiffness of a biological ankle over a range of ambulation tasks. The device stiffness depends on rate of movement, ranging from a dissipating support at very slow walking speed, to efficient energy storage and return at normal walking speed. The objective here is to design a prosthetic foot that provides a compliant support for slow ambulation, without sacrificing the spring-like energy return beneficial in normal walking. The design is a modification of a commercially available foot and employs material properties to provide a change in stiffness. The velocity dependent properties of a non-Newtonian working fluid provide the rate adaptability. Material properties of components allow for a geometry shift that results in a coupling action, affecting the stiffness of the overall system. The function of an adaptive coupling was tested in linear motion. A prototype prosthetic foot was built, and the speed dependent stiffness measured mechanically. Furthermore, the prototype was tested by a user and body kinematics measured in gait analysis for varying walking speed, comparing the prototype to the original foot model (non-modified). Mechanical evaluation of stiffness shows increase in stiffness of about 60% over the test range and 10% increase between slow and normal walking speed in user testing.

Family doctors can have an active role in identifying significant population needs and solutions. During the COVID-19 epidemic, patient home monitoring with pulse oximetry has been a key aspect of care of patients. However, pandemics bring shortage of medical equipment such as pulse oximeters. Through the local maker community, in a matter of days four "smart" pulse oximeters were built. Following Internet of Things principles, the prototypes were programmed to transmit real-time data through Wi-Fi directly to the doctors. Each pulse oximeter served a family doctor during the pandemic. In this article we describe the process that led to the production of the technology and provide detailed instructions, which have also been shared in maker-oriented websites. Dissemination can potentially lead to additional small-scale productions, limiting future shortages.

Purpose: As the utilization of brachytherapy procedures continues to decline in clinics, a need for accessible training tools is required to help bridge the gap between resident comfort in brachytherapy training and clinical practice. To improve the quality of intracavitary and interstitial high-dose-rate brachytherapy education, a multimaterial, modular, three-dimensionally printed pelvic phantom prototype simulating normal and cervical pathological conditions has been developed.
Methods and Materials: Patient anatomy was derived from pelvic CT and MRI scans from 50 representative patients diagnosed with localized cervical cancer. Dimensions measured from patients' uterine body and uterine canal sizes were used to construct a variety of uteri based off of the averages and standard deviations of the subjects in our study. Soft-tissue anatomy was three-dimensionally printed using Agilus blends (shore 30 and 70) and modular components using Vero (shore 85).
Results: The kit consists of four uteri, a standard bladder, a standard rectum, two embedded gross tumor volumes, and four clip-on gross tumor volume attachments. The three anteverted uteri in the kit are based on the smallest, the average, and the largest dimensions from our patient set, whereas the retroverted uterus assumes average dimensions.
Conclusions: This educational high-dose-rate gynecological pelvic phantom is an accessible and cost-effective way to improve radiation oncology resident training in intracavitary/interstitial brachytherapy cases. Implementation of this phantom in resident education will allow for more thorough and comprehensive physician training through its ability to transform the patient scenario. It is expected that this tool will help improve confidence and efficiency when performing brachytherapy procedures in patients.
(Copyright © 2020 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Animals, Cats, Dielectric Spectroscopy, Electric Stimulation, Equipment Design, Female, Ink, Male, Neuromuscular Monitoring instrumentation, Rats, Wistar, Sciatic Nerve physiology, Spinal Cord physiology, Urinary Bladder physiology, Zebrafish, Biocompatible Materials, Neuromuscular Monitoring methods, Printing, Three-Dimensional, and Prostheses and Implants

Neuromuscular interfaces are required to translate bioelectronic technologies for application in clinical medicine. Here, by leveraging the robotically controlled ink-jet deposition of low-viscosity conductive inks, extrusion of insulating silicone pastes and in situ activation of electrode surfaces via cold-air plasma, we show that soft biocompatible materials can be rapidly printed for the on-demand prototyping of customized electrode arrays well adjusted to specific anatomical environments, functions and experimental models. We also show, with the monitoring and activation of neuronal pathways in the brain, spinal cord and neuromuscular system of cats, rats and zebrafish, that the printed bioelectronic interfaces allow for long-term integration and functional stability. This technology might enable personalized bioelectronics for neuroprosthetic applications.

Rapid Prototyping (RP) promises to induce a revolutionary impact on how the objects can be produced and used in industrial manufacturing as well as in everyday life. Over the time a standard technique as the 3D Stereolithography (SL) has become a fundamental technology for RP and Additive Manufacturing (AM), since it enables the fabrication of the 3D objects from a cost-effective photocurable resin. Efforts to obtain devices more complex than just a mere aesthetic simulacre, have been spent with uncertain results. The multidisciplinary nature of such manufacturing technique furtherly hinders the route to the fabrication of complex devices. A good knowledge of the bases of material science and engineering is required to deal with SL technological, characterization and testing aspects. In this framework, our study aims to reveal a new approach to obtain RP of complex devices, namely Organic Electro-Chemical Transistors (OECTs), by SL technique exploiting a resin composite based on the conductive poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and the photo curable Poly(ethylene glycol) diacrylate (PEGDA). A comprehensive study is presented, starting from the optimization of composite resin and characterization of its electrochemical properties, up to the 3D OECTs printing and testing. Relevant performances in biosensing for dopamine (DA) detection using the 3D OECTs are reported and discussed too.

Biosynthetic Pathways drug effects, Biotechnology methods, Cell-Free System metabolism, Metabolic Networks and Pathways physiology, Protein Biosynthesis genetics, Protein Biosynthesis physiology, Biosynthetic Pathways physiology, Metabolic Engineering methods, and Synthetic Biology methods

The design and optimization of biosynthetic pathways for industrially relevant, non-model organisms is challenging due to transformation idiosyncrasies, reduced numbers of validated genetic parts and a lack of high-throughput workflows. Here we describe a platform for in vitro prototyping and rapid optimization of biosynthetic enzymes (iPROBE) to accelerate this process. In iPROBE, cell lysates are enriched with biosynthetic enzymes by cell-free protein synthesis and then metabolic pathways are assembled in a mix-and-match fashion to assess pathway performance. We demonstrate iPROBE by screening 54 different cell-free pathways for 3-hydroxybutyrate production and optimizing a six-step butanol pathway across 205 permutations using data-driven design. Observing a strong correlation (r = 0.79) between cell-free and cellular performance, we then scaled up our highest-performing pathway, which improved in vivo 3-HB production in Clostridium by 20-fold to 14.63 ± 0.48 g l -1 . We expect iPROBE to accelerate design-build-test cycles for industrial biotechnology.