This work was financially supported by the National Science Foundation of China (Grant No. 51805009).

1. Assembly of the amplification mechanism
<ol>
	<li>Construct an experimental platform including an improved 3D printer, a strain gauge indicator, a driving device, a support frame, an aluminum bar, a PDMS lens, a smartphone, weights, a printed amplifier (Supplemental Figure 1), and a strain gauge, as shown in Figure 1.</li>
	<li>Set the height of each layer in the printer at 0.05 mm for nylon and 0.2 mm for ABS. Set the diameter of the printing head to 0.2 mm in both cases. Set the temperature of the nozzle to 220 &#176;C for nylon and 100 &#176;C for ABS. Finally, set the printing speed to 2,000 mm/min for nylon and 3,500 mm/min for ABS.</li>
	<li>Adjust the orientation of the spherical extrusion head so that the metal nozzle faces the low-temperature platform and print a contour to ensure a normal extrusion, as shown in Figure 2.</li>
	<li>Hang the nylon and ABS on the column. The front end must enter the printing coil container to be melted by the metal nozzle.</li>
</ol>
2. Assembly of the PDMS microscope
<ol>
	<li>Using a magnetic stirrer, mix the PDMS precursor and the curing agent to obtain a weight ratio of 10:1.</li>
	<li>Place the mixture into the degasser for 40 min to remove bubbles and pour the degassed mixture into the PDMS container of the spherical extrusion head.</li>
	<li>Rotate the spherical extrusion head and the platform so that the plastic nozzle faces the high-temperature platform.</li>
	<li>Set the plastic nozzle increment to 50 &#181;L. Place the bottom end of the pipette device 20 mm29 away from the mold by using the nozzle rotation and the stepper motor in the Z-axis.</li>
	<li>Turn on the hot plate to heat the high-temperature platform. The temperature of the platform is controlled by a non-contact infrared radiation thermometer. 
	NOTE: This study tested temperatures of 140 &#176;C, 160 &#176;C, 180 &#176;C, 200 &#176;C, 220 &#176;C, and 240 &#176;C.</li>
	<li>Squeeze the PDMS container to print the PDMS lens.</li>
	<li>Cool the PDMS lens to room temperature and remove it with rubber tweezers.</li>
	<li>Determine the geometrical parameters of the lens, including the contact angle, the curvature radius, and the droplet diameter, using a three-dimensional shape analyzer.</li>
</ol>
3. Strain measurement for loading tests in the control and test groups
<ol>
	<li>Use a bar made of aluminum 6063 T83 as the cantilever beam. The length, width, and thickness of the cantilever beam should be 380 mm x 51 mm x 3.8 mm, respectively. Fix one end to the operating table with bolts and nuts.</li>
	<li>Draw a cross at the center and 160 mm from the free end of the cantilever beam.</li>
	<li>To remove the oxide layer on the cantilever beam, polish its surface with fine sandpaper before pasting. The grinding direction should be about 45&#176; from the direction of the strain gauge wire grid. Use cotton wool soaked in acetone to wipe the surface of the cantilever beam and the surface of the strain gauge paste.</li>
	<li>Connect the driving device and the strain gauge indicator. Turn on the power. Use a strain gauge mounted onto the center surface of the aluminum bar at its fixed end to measure the strain changes.</li>
	<li>Fix the standard weight to the free end of the cantilever beam to control the concentrated force input. Read the data using a conventional strain gauge indicator with a quarter-bridge connection method.</li>
	<li>Replace the strain gauge with the ABS and nylon amplifiers at the same location.</li>
	<li>Attach the PDMS lens onto the smartphone camera with an 8-megapixel sensor at a focus distance of 29 mm. Adjust the focal length of the camera until a clear image is obtained. Read the displacement of the pointer using the PDMS microscope.</li>
	<li>Repeat steps 3.5 and 3.6, setting the load to 1 N, 2 N, 3 N, 4 N, and 5 N each time.</li>
</ol>
4. Finite element analysis
<ol>
	<li>Establish 3D finite element models of the nylon and ABS parts for strain measurement (see Table of Materials for software used). Import the cantilever beam and the amplifying mechanism into the material library of the software and simulate their placement positions.</li>
	<li>Analyze the mechanical properties of the amplifying mechanism pointer under the action of a cantilever beam.</li>
	<li>Generate meshes for use in 3D geometric models using tetrahedral elements with a fine element size. Refine the flexure hinges, especially the hinge between the pointer and the other bodies. 
	NOTE: The Young moduli of elasticity used for aluminum, nylon, and ABS were 69 GPa, 2 GPa, and 2.3 GPa, respectively. The Poisson ratios used for aluminum, nylon, and ABS were 0.33, 0.44, and 0.394, respectively.</li>
	<li>Apply a concentrated force of 1 N to the center of the free end of the cantilever beam. Repeat with 2 N, 3 N, 4 N, and 5 N.</li>
</ol>

<ol>
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The authors declare no conflicting interests.

The output displacement evolved linearly with the force concentrated at the free end of the cantilever beam and was consistent with the FEA simulations. The sensitivity of the amplifiers was 36.55 &#177; 0.53 &#956;&#949;/&#956;m for nylon and 36.03 &#177; 1.34 &#956;&#949;/&#956;m for ABS. The stable sensitivity confirmed the feasibility and the effectiveness of the rapid prototyping of high-precision sensors using 3D printing. The amplifiers had a high sensitivity and were free of electromagnetic interference. In addit...

Obtaining light but strong materials is particularly important in modern industry. The properties of materials are affected when subjected to stress, pressure, torsion, and bending vibration during use1,2. Thus, strain measurement of materials is important to analyze their durability and troubleshoot usage. Such measurements enable engineers to analyze the durability of materials and troubleshoot production problems. The most common strain measurement method in industry uses strain sensors3. Traditional foil sensors are widely used because of their low cost and good reliability4. They measure the changes in electrical signals and convert them to different output signals5,6. However, this method leaves out the details of the strain profile in the measured object and is susceptible to noise from vibrational electromagnetic interference with analog signals. Developing accurate, highly repeatable, and easy material strain measurement methods is important in engineering. Thus, other methods are being studied.
In recent years, nanomaterials have drawn much interest from investigators. To measure strain on small objects, Osborn et al.7,8 proposed a method to measure the strain of 3D nanomaterials using electron backscatter (EBSD). Using molecular dynamics, Lina et al.9 investigated the interlayer friction strain engineering of graphene. Distributed optical fiber strain measurements using Rayleigh backscatter spectroscopy (RBS) have been widely used in fault detection and for the evaluation of optical devices due to their high spatial resolution and sensitivity10. Grating fiber optic (FBG)11,12 distributed strain sensors have been widely used for high-precision strain measurement13 for their sensitivity to temperature and strain. In order to monitor the strain changes caused by curing after resin injection, Sanchez et al.14 embedded a fiberoptic sensor into an epoxy carbon fiber plate and measured the complete strain process. Differential interference contrast (DIC) is a powerful measurement method of the field deformation15,16,17 that is widely used as well18. By comparing the changes of measured surface gray levels in the collected images, the deformation is analyzed, and the strain calculated. Zhang et al.19 proposed a method that relies on the introduction of reinforced particles and DIC images to evolve from traditional DIC. Vogel and Lee20 calculated strain values using an automatic two-view method. In recent years, this enabled simultaneous microstructure observation and strain measurement in particle-reinforced composites. Traditional strain sensors only effectively measure strain in one direction. Zymelka et al.21 proposed an omnidirectional flexible strain sensor that improves a traditional strain gauge method by detecting changes in the sensor resistance. It is also possible to measure strain using biological or chemical substances. For instance, ionic conductive hydrogels are an effective alternative to strain/tactile sensors due to their good tensile properties and high sensitivity22,23. Graphene and its composites have excellent mechanical properties and provide a high carrier mobility along with good piezoresistivity24,25,26. Consequently, graphene-based strain sensors have been widely used in electronic skin health monitoring, wearable electronics, and other fields27,28.
In this work, a conceptual strain measurement using a polydimethylsiloxane (PDMS) microscope and an amplification system is presented. The device is different from a traditional strain gauge because it does not require wires or electrical connections. Moreover, displacement can be observed directly. The amplification mechanism can be placed at any location on the tested object, which greatly increases the repeatability of the measurements. In this study, a sensor and a strain amplifier were made by 3D printing technology. We first improved the 3D printer to increase its efficiency for our requirements. A spherical extrusion device was designed to replace the traditional single-material extruder controlled by the slicing software to complete the conversion of the metal and plastic nozzles. The corresponding molding platform was changed, and the displacement-sensing device (amplifier) and the reading device (PDMS microscope) were integrated.

<table><tbody><tr><td>ABS</td><td>Hengli dejian plastic electrical products factory</td><td></td><td>Used for printing 1.75 mm diameter wire for amplifying mechanism</td></tr><tr><td>Aluminum 6063 T83 bar</td><td></td><td></td><td>The length, width and thickness of cantilever beam are 380 mm, 51 mm, and 3.8 mm.</td></tr><tr><td>ANSYS</td><td>ANSYS</td><td>ANSYS 14.5</td><td></td></tr><tr><td>CURA</td><td>Ultimaker</td><td>Cura 3.0</td><td>Slicing softare,using with the improved 3D printer</td></tr><tr><td>Curing agent</td><td>Dow Corning</td><td></td><td>PDMS and curing agent are mixed with the weight ratio of 10:1</td></tr><tr><td>Driving device</td><td>Xinmingtian</td><td>E00</td><td></td></tr><tr><td>Improved 3D printer and accessories</td><td></td><td></td><td>Made by myself. The rotary spherical lifting platform is adopted. The spherical lifting platform is equipped with a nozzle and a pipette, which can be switched and printed freely. With a rotary printing platform, the platform temperature can be freely controlled.</td></tr><tr><td>iPhone 6</td><td>Apple</td><td>MG4A2CH/A</td><td>8-megapixel sensor and the equivalent focus distance is 29mm</td></tr><tr><td>Magenetic stirrer</td><td>SCILOGEX</td><td>MS-H280-Pro</td><td></td></tr><tr><td>Nylon</td><td>Hengli dejian plastic electrical products factory</td><td></td><td>Used for printing 1.75 mm diameter wire for amplifying mechanism</td></tr><tr><td>PDMS</td><td>Dow Corning</td><td>SYLGARDDC184</td><td>After the viscous mixture is heated and hardened, it can be combined with the lens amplification device of the mobile phone for image acquisition.</td></tr><tr><td>Shape analyzer</td><td>Gltech</td><td>SURFIEW 4000</td><td></td></tr><tr><td>Solidworks</td><td>Dassault Systems</td><td>Solidworks 2017</td><td>Assist to modelling</td></tr><tr><td>VISHAY strain gauge</td><td>Vishay</td><td></td><td>Used to measure the strain produced in the experiment.</td></tr><tr><td>VISHAY strain gauge indicator</td><td>Vishay</td><td></td><td>Strain data acquisition.</td></tr></tbody></table>

production of a strain-measuring device with an improved 3d printer

A traditional strain measurement sensor needs to be electrified and is susceptible to electromagnetic interference. In order to solve the fluctuations in the analog electrical signal in a traditional strain gauge operation, a new strain measurement method is presented here. It uses a photographic technique to display the strain change by amplifying the change of the pointer displacement of the mechanism. A visual polydimethylsiloxane (PDMS) lens with a focal length of 7.16 mm was added to a smartphone camera to generate a lens group acting as a microscope to capture images. It had an equivalent focal length of 5.74 mm. Acrylonitrile butadiene styrene (ABS) and nylon amplifiers were used to test the influence of different materials on the sensor performance. The production of the amplifiers and PDMS lens is based on improved 3D printing technology. The data obtained were compared with the results from finite element analysis (FEA) to verify their validity. The sensitivity of the ABS amplifier was 36.03 &plusmn; 1.34 &#181;&epsilon;/&#181;m, and the sensitivity of the nylon amplifier was 36.55 &plusmn; 0.53 &#181;&epsilon;/&#181;m.

When the platform temperature increased, the droplet diameter and the curvature radius decreased, whereas the contact angle increased (Figure 3). Therefore, the focal length of the PDMS increased. However, for platform temperatures above 220 &#176;C, a very short curing time was observed in the droplets, and they could not extend into a plane-convex shape. This can be attributed to the low attachment area when adhering onto a smartphone camera. Therefore, only soft lenses formed at 220 &#176...

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Production of a Strain-Measuring Device with an Improved 3D Printer

This work presents a strain measurement sensor consisting of an amplification mechanism and a polydimethylsiloxane microscope manufactured using an improved 3D printer.

A traditional strain measurement sensor needs to be electrified and is susceptible to electromagnetic interference. In order to solve the fluctuations in ...

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5.8K Views.  Beijing Technology and Business University. This work presents a strain measurement sensor consisting of an amplification mechanism and a polydimethylsiloxane microscope manufactured using an improved 3D printer.

Video: Production of a Strain-Measuring Device with an Improved 3D Printer

A Microfluidic Device for Studying Multiple Distinct Strains

The study of cell responses to environmental changes poses many experimental challenges: cells need to be imaged under changing conditions, often in a comparative manner. Multiwell plates are routinely used to compare many different strains or cell lines, but allow limited control over the environment dynamics. Microfluidic devices, on the other hand, allow exquisite dynamic control over the surrounding conditions, but it is challenging to image and distinguish more than a few strains in them. Here we describe a method to easily and rapidly manufacture a microfluidic device capable of applying dynamically changing conditions to multiple distinct yeast strains in one channel. The device is designed and manufactured by simple means without the need for soft lithography. It is composed of a Y-shaped flow channel attached to a second layer harboring microwells. The strains are placed in separate microwells, and imaged under the exact same dynamic conditions. We demonstrate the use of the device for measuring protein localization responses to pulses of nutrient changes in different yeast strains.

We present a simple method to produce microfluidic devices capable of applying similar dynamic conditions to multiple distinct strains, without the need for a clean room or soft lithography.

The study of cell responses to environmental changes poses many experimental challenges: cells need to be imaged under changing conditions, often in a ...

Bioengineering

Rapid and Low-cost Prototyping of Medical Devices Using 3D Printed Molds for Liquid Injection Molding

Biologically inert elastomers such as silicone are favorable materials for medical device fabrication, but forming and curing these elastomers using traditional liquid injection molding processes can be an expensive process due to tooling and equipment costs. As a result, it has traditionally been impractical to use liquid injection molding for low-cost, rapid prototyping applications. We have devised a method for rapid and low-cost production of liquid elastomer injection molded devices that utilizes fused deposition modeling 3D printers for mold design and a modified desiccator as an injection system. Low costs and rapid turnaround time in this technique lower the barrier to iteratively designing and prototyping complex elastomer devices. Furthermore, CAD models developed in this process can be later adapted for metal mold tooling design, enabling an easy transition to a traditional injection molding process. We have used this technique to manufacture intravaginal probes involving complex geometries, as well as overmolding over metal parts, using tools commonly available within an academic research laboratory. However, this technique can be easily adapted to create liquid injection molded devices for many other applications.

We have devised a method for low-cost and rapid prototyping of liquid elastomer rubber injection molded devices by using fused deposition modeling 3D printers for mold design and a modified desiccator as a liquid injection system.

Biologically inert elastomers such as silicone are favorable materials for medical device fabrication, but forming and curing these elastomers using ...

Design and Development of a Three-Dimensionally Printed Microscope Mask Alignment Adapter for the Fabrication of Multilayer Microfluidic Devices

This project aims to develop an easy-to-use and cost-effective platform for the fabrication of precise, multilayer microfluidic devices, which typically can only be achieved using costly equipment in a clean room setting. The key part of the platform is a three dimensionally (3D) printed microscope mask alignment adapter (MMAA) compatible with regular optical microscopes and ultraviolet (UV) light exposure systems. The overall process of creating the device has been vastly simplified because of the work done to optimize the device design. The process entails finding the proper dimensions for the equipment available in the laboratory and 3D-printing the MMAA with the optimized specifications. Experimental results show that the optimized MMAA designed and manufactured by 3D printing performs well with a common microscope and light exposure system. Using a master mold prepared by the 3D-printed MMAA, the resulting microfluidic devices with multilayered structures contain alignment errors of &lt;10 &#181;m, which is sufficient for common microchips. Although human error through transportation of the device to the UV light exposure system can cause larger fabrication errors, the minimal errors achieved in this study are attainable with practice and care. Furthermore, the MMAA can be customized to fit any microscope and UV exposure system by making changes to the modeling file in the 3D printing system. This project provides smaller laboratories with a useful research tool as it only requires the use of equipment that is typically already available to laboratories that produce and use microfluidic devices. The following detailed protocol outlines the design and 3D printing process for the MMAA. In addition, the steps for procuring a multilayer master mold using the MMAA and producing poly(dimethylsiloxane) (PDMS) microfluidic chips is also described herein.

This project allows small laboratories to develop an easy-to-use platform for the fabrication of precise multilayer microfluidic devices. The platform consists of a three-dimensionally printed microscope mask alignment adapter using which multilayer microfluidic devices with alignment errors of &lt;10 &#181;m were achieved.

This project aims to develop an easy-to-use and cost-effective platform for the fabrication of precise, multilayer microfluidic devices, which typically ...

Visualizing Polymer Dynamics for Optimizing 3D Printing Quality

Real-Time Imaging of Bonding in 3D-Printed Layers

In recent times, 3D printing technology has revolutionized our ability to design and produce products, but optimizing the print quality can be challenging. The process of extrusion 3D printing involves pressuring molten material through a thin nozzle and depositing it onto previously extruded material. This method relies on bonding between the consecutive layers to create a strong and visually appealing final product. This is no easy task, as many parameters, such as the nozzle temperature, layer thickness, and printing speed, must be fine-tuned to achieve optimal results. In this study, a method for visualizing the polymer dynamics during extrusion is presented, giving insight into the layer bonding process. Using laser speckle imaging, the plastic flow and fusion can be resolved non-invasively, internally, and with high spatiotemporal resolution. This measurement, which is easy to perform, provides an in-depth understanding of the underlying mechanics influencing the final print quality. This methodology was tested with a range of cooling fan speeds, and the results showed increased polymer motion with lower fan speeds and, thus, explained the poor printing quality when the cooling fan was turned off. These findings show that this methodology allows for optimizing the printing settings and understanding the material behavior. This information can be used for the development and testing of novel printing materials or advanced slicing procedures. With this approach, a deeper understanding of extrusion can be built to take 3D printing to the next level.

Author Spotlight: Real-Time Imaging of Bonding in 3D-Printed Layers  

With a non-invasive and real-time technique, nanoscopic polymer motion inside a polymer filament is imaged during 3D printing. Fine-tuning this motion is crucial for producing constructs with optimal performance and appearance. This method reaches the core of plastic layer fusion, thus offering insights into optimal printing conditions and material design criteria.

In recent times, 3D printing technology has revolutionized our ability to design and produce products, but optimizing the print quality can be ...

Three-dimensional Patterning of Engineered Biofilms with a Do-it-yourself Bioprinter

Biofilms are aggregates of bacteria embedded in a self-produced spatially-patterned extracellular matrix. Bacteria within a biofilm develop enhanced antibiotic resistance, which poses potential health dangers, but can also be beneficial for environmental applications such as purification of drinking water. The further development of anti-bacterial therapeutics and biofilm-inspired applications will require the development of reproducible, engineerable methods for biofilm creation. Recently, a novel method of biofilm preparation using a modified three-dimensional (3D) printer with a bacterial ink has been developed. This article describes the steps necessary to build this efficient, low-cost 3D bioprinter that offers multiple applications in bacterially-induced materials processing. The protocol begins with an adapted commercial 3D printer in which the extruder has been replaced with a bio-ink dispenser connected to a syringe pump system enabling a controllable, continuous flow of bio-ink. To develop a bio-ink suitable for biofilm printing, engineered Escherichia coli bacteria were suspended in a solution of alginate, so that they solidify in contact with a surface containing calcium. The inclusion of an inducer chemical within the printing substrate drives expression of biofilm proteins within the printed bio-ink. This method enables 3D printing of various spatial patterns composed of discrete layers of printed biofilms. Such spatially-controlled biofilms can serve as model systems and can find applications in multiple fields that have a wide-ranging impact on society, including antibiotic resistance prevention or drinking water purification, among others.

This article describes a method of transforming a low-cost commercial 3D printer into a bacterial 3D printer that can facilitate printing of patterned biofilms. All necessary aspects of preparing the bioprinter and bio-ink are described, as well as verification methods to assess the formation of biofilms.

Biofilms are aggregates of bacteria embedded in a self-produced spatially-patterned extracellular matrix. Bacteria within a biofilm develop enhanced ...

Design of an Open-Source, Low-Cost Bioink and Food Melt Extrusion 3D Printer

Three-dimensional (3D) printing is an increasingly popular manufacturing technique that allows highly complex objects to be fabricated with no retooling costs. This increasing popularity is partly driven by falling barriers to entry such as system set-up costs and ease of operation. The following protocol presents the design and construction of an Additive Manufacturing Melt Extrusion (ADDME) 3D printer for the fabrication of custom parts and components. ADDME has been designed with a combination of 3D-printed, laser-cut, and online-sourced components. The protocol is arranged into easy-to-follow sections, with detailed diagrams and parts lists under the headings of framing, y-axis and bed, x-axis, extrusion, electronics, and software. The performance of ADDME is evaluated through extrusion testing and 3D printing of complex objects using viscous cream, chocolate, and Pluronic F-127 (a model for bioinks). The results indicate that ADDME is a capable platform for the fabrication of materials and constructs for use in a wide range of industries. The combination of detailed diagrams and video content facilitates access to low-cost, easy-to-operate equipment for individuals interested in 3D printing of complex objects from a wide range of materials.

The aim of this work is to design and construct a reservoir-based melt extrusion three-dimensional printer made from open-source and low-cost components for applications in the biomedical and food printing industries.

Three-dimensional (3D) printing is an increasingly popular manufacturing technique that allows highly complex objects to be fabricated with no retooling ...

Controlled Strain of 3D Hydrogels under Live Microscopy Imaging

External forces are an important factor in tissue formation, development, and maintenance. The effects of these forces are often studied using specialized in vitro stretching methods. Various available systems use 2D substrate-based stretchers, while the accessibility of 3D techniques to strain soft hydrogels, is more restricted. Here, we describe a method that allows external stretching of soft hydrogels from their circumference, using an elastic silicone strip as the sample carrier. The stretching system utilized in this protocol is constructed from 3D-printed parts and low-cost electronics, making it simple and easy to replicate in other labs. The experimental process begins with polymerizing thick (&#62;100 &#956;m) soft fibrin hydrogels (Elastic Modulus of ~100 Pa) in a cut-out at the center of a silicone strip. Silicone-gel constructs are then attached to the printed-stretching device and placed on the confocal microscope stage. Under live microscopy the stretching device is activated, and the gels are imaged at various stretch magnitudes. Image processing is then used to quantify the resulting gel deformations, demonstrating relatively homogenous strains and fiber alignment throughout the gel&#8217;s 3D thickness (Z-axis). Advantages of this method include the ability to strain extremely soft hydrogels in 3D while executing in situ microscopy, and the freedom to manipulate the geometry and size of the sample according to the user&#8217;s needs. Additionally, with proper adaptation, this method can be used to stretch other types of hydrogels (e.g., collagen, polyacrylamide or polyethylene glycol) and can allow for analysis of cells and tissue response to external forces under more biomimetic 3D conditions.

The presented method involves uniaxial stretching of 3D soft hydrogels embedded in silicone rubber while allowing live confocal microscopy. Characterization of the external and internal hydrogel strains as well as fiber alignment are demonstrated. The device and protocol developed can assess the response of cells to various strain regimes.

External forces are an important factor in tissue formation, development, and maintenance. The effects of these forces are often studied using specialized ...

Bioprinting Bacteria in Hydrogel Matrices for the Study of Motility and Growth

3D Printing Bacteria to Study Motility and Growth in Complex 3D Porous Media

Bacteria are ubiquitous in complex three-dimensional (3D) porous environments, such as biological tissues and gels, and subsurface soils and sediments. However, the majority of previous work has focused on studies of cells in bulk liquids or at flat surfaces, which do not fully recapitulate the complexity of many natural bacterial habitats. Here, this gap in knowledge is addressed by describing the development of a method to 3D-print dense colonies of bacteria into jammed granular hydrogel matrices. These matrices have tunable pore sizes and mechanical properties; they physically confine the cells, thus supporting them in 3D. They are optically transparent, allowing for direct visualization of bacterial spreading through their surroundings using imaging. As a proof of this principle, here, the capability of this protocol is demonstrated by 3D printing and imaging non-motile and motile Vibro cholerae, as well as non-motile Escherichia coli, in jammed granular hydrogel matrices with varying interstitial pore sizes.

Author Spotlight: Studying Bacterial Growth in 3D Hydrogel Matrices

This protocol describes a procedure for three-dimensional (3D) printing of bacterial colonies to study their motility and growth in complex 3D porous hydrogel matrices that are more akin to their natural habitats than conventional liquid cultures or Petri dishes.

Bacteria are ubiquitous in complex three-dimensional (3D) porous environments, such as biological tissues and gels, and subsurface soils and sediments. ...

Production and Analysis of Sporosarcina pasteurii Biocement Bricks Using Custom 3D-Printed Molds for Unconfined Compression Tests

Cement is a key building material used in many structures across the globe, from foundations for homes to historical monuments and roadways. It is a critical and abundant material worldwide. However, the traditional production of cement is a major contributor to man-made atmospheric CO2, leading to greenhouse gas emissions and climate change. Microbially induced calcite precipitation (MICP) is a biological process in which Sporosarcina pasteurii or other bacteria produce a cement material that is as strong as traditional cement, but biocement is carbon-neutral. This MICP method of producing biocement is a promising technology and is currently under active investigation by many companies, countries, and research groups. The protocol presented here employs custom-designed, reusable, 3D-printed molds for flow-through MICP treatment of soil or sand, producing cylindrical bricks that meet standard specifications for unconfined compression tests. The individual, free-standing, reservoir-topped molds allow convenient parallel testing of multiple variables and replicates. This protocol outlines the S. pasteurii MICP reaction and the creation, assembly, and use of the 3D-printed molds to generate biocement cylindrical bricks.

Sporosarcina pasteurii is a ureolytic bacterium that breaks down urea into carbonate and ammonium. The carbonate combines with calcium to form calcium carbonate, creating a crystal lattice that anchors surrounding particles together to produce biocement. This is a convenient protocol for using 3D-printed molds to create biocement bricks suitable for compression testing.

Cement is a key building material used in many structures across the globe, from foundations for homes to historical monuments and roadways. It is a ...

Creation of a High-Fidelity, Low-Cost, Intraosseous Line Placement Task Trainer via 3D Printing

The description of procedural task trainers includes their use as a training tool to hone technical skills through repetition and rehearsal of procedures in a safe environment before ultimately performing the procedure on a patient. Many procedural task trainers available to date suffer from several drawbacks, including unrealistic anatomy and the tendency to develop user-created &#39;landmarks&#39; after the trainer tissue undergoes repeated manipulations, potentially leading to inappropriate psychomotor skill development. To ameliorate these drawbacks, a process was created to produce a high-fidelity procedural task trainer, created from anatomy obtained from computed tomography (CT) scans, that utilize ubiquitous three-dimensional (3D) printing technology and off-the-shelf commodity supplies.
This method includes creating a 3D printed tissue mold capturing the tissue structure surrounding the skeletal element of interest to encase the bony skeletal structure suspended within the tissue, which is also 3D printed. A tissue medium mixture, which approximates tissue in both high-fidelity geometry and tissue density, is then poured into a mold and allowed to set. After a task trainer has been used to practice a procedure, such as intraosseous line placement, the tissue media, molds, and bones are reclaimable and may be reused to create a fresh task trainer, free of puncture sites and manipulation defects, for use in subsequent training sessions.

We describe a procedure to process computed tomography (CT) scans into high-fidelity, reclaimable, and low-cost procedural task trainers. The CT scan identification processes, export, segmentation, modeling, and 3D printing are all described, along with the issues and lessons learned in the process.

The description of procedural task trainers includes their use as a training tool to hone technical skills through repetition and rehearsal of procedures ...