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>

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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 border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<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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5.7K 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

High-resolution, High-speed, Three-dimensional Video Imaging with Digital Fringe Projection Techniques

Digital fringe projection (DFP) techniques provide dense 3D measurements of dynamically changing surfaces.&#160;Like the human eyes and brain, DFP uses triangulation between matching points in two views of the same scene at different angles to compute depth.&#160;However, unlike a stereo-based method, DFP uses a digital video projector to replace one of the cameras1. The projector rapidly projects a known sinusoidal pattern onto the subject, and the surface of the subject distorts these patterns in the camera&#8217;s field of view. Three distorted patterns (fringe images) from the camera can be used to compute the depth using triangulation.
Unlike other 3D measurement methods, DFP techniques lead to systems that tend to be faster, lower in equipment cost, more flexible, and easier to develop.&#160;DFP systems can also achieve the same measurement resolution as the camera.&#160;For this reason, DFP and other digital structured light techniques have recently been the focus of intense research (as summarized in1-5). Taking advantage of DFP, the graphics processing unit, and optimized algorithms, we have developed a system capable of 30&#160;Hz 3D video data acquisition, reconstruction, and display for over 300,000 measurement points per frame6,7.&#160;Binary defocusing DFP methods can achieve even greater speeds8.
Diverse applications can benefit from DFP techniques. Our collaborators have used our systems for facial function analysis9, facial animation10, cardiac mechanics studies11, and fluid surface measurements, but many other potential applications exist.&#160;This video will teach the fundamentals of DFP techniques and illustrate the design and operation of a binary defocusing DFP system.

This video describes the fundamentals of digital fringe projection techniques, which provide dense 3D measurements of dynamically changing surfaces.&#160;It also demonstrates the design and operation of a high-speed binary defocusing system based on these techniques.

Digital fringe projection (DFP) techniques provide dense 3D measurements of dynamically changing surfaces.&#160;Like the human eyes and brain, DFP uses ...

Development of a 3D Graphene Electrode Dielectrophoretic Device

The design and fabrication of a novel 3D electrode microdevice using 50 &#181;m thick graphene paper and 100 &#181;m double sided tape is described. The protocol details the procedures to construct a versatile, reusable, multiple layer, laminated dielectrophoresis chamber. Specifically, six layers of 50 &#181;m x&#160;0.7 cm x&#160;2 cm graphene paper and five layers of double sided tape were alternately stacked together, then clamped to a glass slide. Then a 700 &#956;m diameter micro-well was drilled through the laminated structure using a computer-controlled micro drilling machine. Insulating properties of the tape layer between adjacent graphene layers were assured by resistance tests. Silver conductive epoxy connected alternate layers of graphene paper and formed stable connections between the graphene paper and external copper wire electrodes. The finished device was then clamped and sealed to a glass slide. The electric field gradient was modeled within the multi-layer device. Dielectrophoretic behaviors of 6 &#956;m polystyrene beads were demonstrated in the 1 mm deep micro-well, with medium conductivities ranging from 0.0001 S/m to 1.3 S/m, and applied signal frequencies from 100 Hz to 10 MHz. Negative dielectrophoretic responses were observed in three dimensions over most of the conductivity-frequency space and cross-over frequency values are consistent with previously reported literature values. The device did not prevent AC electroosmosis and electrothermal flows, which occurred in the low and high frequency regions, respectively. The graphene paper utilized in this device is versatile and could subsequently function as a biosensor after dielectrophoretic characterizations are complete.

A microdevice with high throughput potential is used to demonstrate three-dimensional (3D) dielectrophoresis (DEP) with novel materials. Graphene nanoplatelet paper and double sided tape were alternately stacked; a 700 &#956;m micro-well was drilled transverse to the layers. DEP behavior of polystyrene beads was demonstrated in the micro-well.

The design and fabrication of a novel 3D electrode microdevice using 50 &#181;m thick graphene paper and 100 &#181;m double sided tape is described. The ...

Hand Controlled Manipulation of Single Molecules via a Scanning Probe Microscope with a 3D Virtual Reality Interface

Considering organic molecules as the functional building blocks of future nanoscale technology, the question of how to arrange and assemble such building blocks in a bottom-up approach is still open. The scanning probe microscope (SPM) could be a tool of choice; however, SPM-based manipulation was until recently limited to two dimensions (2D). Binding the SPM tip to a molecule at a well-defined position opens an opportunity of controlled manipulation in 3D space. Unfortunately, 3D manipulation is largely incompatible with the typical 2D-paradigm of viewing and generating SPM data on a computer. For intuitive and efficient manipulation we therefore couple a low-temperature non-contact atomic force/scanning tunneling microscope (LT NC-AFM/STM) to a motion capture system and fully immersive virtual reality goggles. This setup permits &#34;hand controlled manipulation&#34; (HCM), in which the SPM tip is moved according to the motion of the experimenter&#39;s hand, while the tip trajectories as well as the response of the SPM junction are visualized in 3D. HCM paves the way to the development of complex manipulation protocols, potentially leading to a better fundamental understanding of nanoscale interactions acting between molecules on surfaces. Here we describe the setup and the steps needed to achieve successful hand-controlled molecular manipulation within the virtual reality environment.

We demonstrate the precise manipulation of individual organic molecules on a metal surface with the tip of a scanning probe microscope driven in 3D by the experimenter's hand using a motion capture system and fully immersive virtual reality goggles.

Considering organic molecules as the functional building blocks of future nanoscale technology, the question of how to arrange and assemble such building ...

The Modular Design and Production of an Intelligent Robot Based on a Closed-Loop Control Strategy

Intelligent robots are part of a new generation of robots that are able to sense the surrounding environment, plan their own actions and eventually reach their targets. In recent years, reliance upon robots in both daily life and industry has increased. The protocol proposed in this paper describes the design and production of a handling robot with an intelligent search algorithm and an autonomous identification function.
First, the various working modules are mechanically assembled to complete the construction of the work platform and the installation of the robotic manipulator. Then, we design a closed-loop control system and a four-quadrant motor control strategy, with the aid of debugging software, as well as set steering gear identity (ID), baud rate and other working parameters to ensure that the robot achieves the desired dynamic performance and low energy consumption. Next, we debug the sensor to achieve multi-sensor fusion to accurately acquire environmental information. Finally, we implement the relevant algorithm, which can recognize the success of the robot&#39;s function for a given application.
The advantage of this approach is its reliability and flexibility, as the users can develop a variety of hardware construction programs and utilize the comprehensive debugger to implement an intelligent control strategy. This allows users to set personalized requirements based on their needs with high efficiency and robustness.

We present a protocol on modular design and production of intelligent robots to help scientific and technical workers design intelligent robots with special production tasks based on personal needs and individualized design.

Intelligent robots are part of a new generation of robots that are able to sense the surrounding environment, plan their own actions and eventually reach ...

A 3D-printed Chamber for Organic Optoelectronic Device Degradation Testing

In this manuscript, we outline the manufacture of a small, portable, easy-to-use atmospheric chamber for organic and perovskite optoelectronic devices, using 3D-printing. As these types of devices are sensitive to moisture and oxygen, such a chamber can aid researchers in characterizing the electronic and stability properties. The chamber is intended to be used as a temporary, reusable, and stable environment with controlled properties (including humidity, gas introduction, and temperature). It can be used to protect air-sensitive materials or to expose them to contaminants in a controlled way for degradation studies. To characterize the properties of the chamber, we outline a simple procedure to determine the water vapor transmission rate (WVTR) using relative humidity as measured by a standard humidity sensor. This standard operating procedure, using a 50% infill density of polylactic acid (PLA), results in a chamber that can be used for weeks without any significant loss of device properties. The versatility and ease of use of the chamber allows it to be adapted to any characterization condition that requires a compact-controlled atmosphere.

Here, we present a protocol for the design, manufacture, and use of a simple, versatile 3D-printed and controlled atmospheric chamber for the optical and electrical characterization of air-sensitive organic optoelectronic devices.

In this manuscript, we outline the manufacture of a small, portable, easy-to-use atmospheric chamber for organic and perovskite optoelectronic devices, ...

A Soft Tooling Process Chain for Injection Molding of a 3D Component with Micro Pillars

The purpose of this paper is to present the method of a soft tooling process chain employing Additive Manufacturing (AM) for fabrication of injection molding inserts with micro surface features. The Soft Tooling inserts are manufactured by Digital Light Processing (vat photo polymerization) using a photopolymer that can withstand relatively high temperaturea. The part manufactured here has four tines with an angle of 60&#176;. Micro pillars (&#216;200 &#181;m, aspect ratio of 1) are arranged on the surfaces by two rows. Polyethylene (PE) injection molding with the soft tooling inserts is used to fabricate the final parts. This method demonstrates that it is feasible to obtain injection-molded parts with microstructures on complex geometry by additive manufactured inserts. The machining time and cost is reduced significantly compared to conventional tooling processes based on computer numerical control (CNC) machining. The dimensions of the micro features are influenced by the applied additive manufacturing process. The lifetime of the inserts determines that this process is more suitable for pilot production. The precision of the inserts production is limited by the additive manufacturing process as well.

A protocol for fabricating injection molding inserts for complex geometry with micro features on surfaces employing Additive Manufacturing (AM) is presented.

The purpose of this paper is to present the method of a soft tooling process chain employing Additive Manufacturing (AM) for fabrication of injection ...

A Standard and Reliable Method to Fabricate Two-Dimensional Nanoelectronics

Two-dimensional (2D) materials have attracted huge attention due to their unique properties and potential applications. Since wafer scale synthesis of 2D materials is still in nascent stages, scientists cannot fully rely on traditional semiconductor techniques for related research. Delicate processes from locating the materials to electrode definition need to be well controlled. In this article, a universal fabrication protocol required in manufacturing nanoscale electronics, such as 2D quasi-heterojunction bipolar transistors (Q-HBT), and 2D back-gated transistors are demonstrated. This protocol includes the determination of material position, electron beam lithography (EBL), metal electrode definition, et al. A step by step narrative of the fabrication procedures for these devices are also presented. Furthermore, results show that each of the fabricated devices has achieved high performance with high repeatability. This work reveals a comprehensive description of process flow for preparing 2D nano-electronics, enables the research groups to access this information, and pave the way toward future electronics.

The article aims to introduce a standard and reliable fabrication procedure for the development of future low dimensional nanoelectronics.

Two-dimensional (2D) materials have attracted huge attention due to their unique properties and potential applications. Since wafer scale synthesis of 2D ...

A Polymer-based Piezoelectric Vibration Energy Harvester with a 3D Meshed-Core Structure

In this study, we fabricated a flexible 3D mesh structure with periodic voids by using a 3D lithography method and applying it to a vibration energy harvester to lower resonance frequency and increase output power. The fabrication process is mainly divided into two parts: three-dimensional photolithography for processing a 3D mesh structure, and a bonding process of piezoelectric films and the mesh structure. With the fabricated flexible mesh structure, we achieved the reduction of resonance frequency and improvement of output power, simultaneously. From the results of the vibration tests, the meshed-core-type vibration energy harvester (VEH) exhibited 42.6% higher output voltage than the solid-core-type VEH. In addition, the meshed-core-type VEH yielded 18.7 Hz of resonance frequency, 15.8% lower than the solid-core-type VEH, and 24.6 &#956;W of output power, 68.5% higher than the solid-core-type VEH. The advantage of the proposed method is that a complex and flexible structure with voids in three dimensions can be relatively easily fabricated in a short time by the inclined exposure method. As it is possible to lower the resonance frequency of the VEH by the mesh structure, use in low-frequency applications, such as wearable devices and house appliances, can be expected in the future.

In this study, we fabricated a flexible 3D mesh structure and applied it to the elastic layer of a bimorph cantilever-type vibration energy harvester for the purpose of lowering resonance frequency and increasing output power.

In this study, we fabricated a flexible 3D mesh structure with periodic voids by using a 3D lithography method and applying it to a vibration energy ...

3D Printing - Evaluating Particle Emissions of a 3D Printing Pen

Three-dimensional (3D) printing as a type of additive manufacturing shows continuing increase in application and consumer popularity. The fused filament fabrication (FFF) is an inexpensive method used most frequently by consumers. Studies with 3D printers have shown that during the printing process particulate and volatile substances are released. Handheld 3D printing pens also use the FFF method but the consumer&#8217;s proximity to the 3D pens gives reason to higher exposure compared to a 3D printer. At the same time, 3D printing pens are often marketed for children who could be more sensitive to the printing emission. The aim of this study was to implement a low cost method to analyze the emissions of 3D printing pens. Polylactide (PLA) and acrylonitrile butadiene styrene (ABS) filaments of different colors were tested. In addition, filaments containing metal and carbon nanotubes (CNTs) were analyzed. An 18.5 L chamber and sampling close to the emission source was used to characterize emissions and concentrations near the breathing zone of the user.
Particle emissions and particle size distributions were measured and the potential release of metal particles and CNTs investigated. Particle number concentrations were found in a range of 105 - 106 particles/cm3, which is comparable to previous reports from 3D printers. Transmission electron microscopy (TEM) analysis showed nanoparticles of the different thermoplastic materials as well as of metal particles and CNTs. High contents of metal were observed by inductively coupled plasma mass spectrometry (ICP-MS).
These results call for a cautious use of 3D pens due to potential risk to the consumers.

This protocol presents a method to analyze the emission of 3D printing pens. Particle concentration and particle size distribution of the released particle is measured. Released particles are further analyzed with transmission electron microscopy (TEM). Metal content in filaments is quantified by inductively coupled plasma mass spectrometry (ICP-MS).

Three-dimensional (3D) printing as a type of additive manufacturing shows continuing increase in application and consumer popularity. The fused filament ...

Elaborate Control of Inkjet Printer for Fabrication of Chip-based Supercapacitors

There are tremendous efforts in various fields to apply the inkjet printing method for the fabrication of wearable devices, displays, and energy storage devices. To get high-quality products, however, sophisticated operation skills are required depending on the physical properties of the ink materials. In this regard, optimizing the inkjet printing parameters is as important as developing the physical properties of the ink materials. In this study, optimization of the inkjet printing software parameters is presented for fabricating a supercapacitor. Supercapacitors are attractive energy storage systems because of their high power density, long lifespan, and various applications as power sources. Supercapacitors can be used in the Internet of Things (IoT), smartphones, wearable devices, electrical vehicles (EVs), large energy storage systems, etc. The wide range of applications demands a new method that can fabricate devices in various scales. The inkjet printing method can break through the conventional fixed-size&#160;fabrication method.

This paper provides a technique for manufacturing chip-based supercapacitors using an inkjet printer. Methodologies are described in detail to synthesize inks, adjust software parameters, and analyze the electrochemical results of the manufactured supercapacitor.

There are tremendous efforts in various fields to apply the inkjet printing method for the fabrication of wearable devices, displays, and energy storage ...