3d printed soft robotics Archives - Perfect 3D Printing Filament

Could 4D Printing Enable the Next Generation of Soft Pneumatic Actuators?

Although 3D printing of actuators is a relatively new field of research, interest in the area has grown due to the potential applications of highly customizable, programmable, small scale actuators in micro/mesoscale robotics., including 3D printed hair-like actuators. A common area of research has been into soft actuators for possible industrial applications, where various 3D printing technologies – FDM, DLP, SLS, inkjet, Direct Ink Writing (DIW) and customized SLA platforms, have been used to build multi-material actuators with improved performance, functionality, design flexibility, and manufacturing efficiency.

Soft Actuator industrial gripper applications. Image Courtesy of Virtual and Physical Prototyping 21 Journal

Traditional manufacturing methods for miniature actuators in soft robotics, molding and soft lithography, were limited—and 3D printing has brought several advantages over them. With 3D printing, the inherent design freedom means actuators can be customized at the very small scale easily and can even be designed to accurately mimic bio-inspired architectures. Applications have now advanced to include 4D printing, as researchers from Deakin University and Trent University have established in this study.

Published in the Visual and Physical Prototyping journal in July, the study applies 4D printing/3D printing technologies in fabricating Soft bending-type Pneumatic Actuators (SPA), that respond to changes in air pressure. These 4D/3D printed actuators are made using elastomers and are able to deliver a range of motions, such as bending, twisting, rotating, rolling, jumping, in response to simple changes in air pressure.

Image Courtesy of Virtual and Physical Prototyping 21 Journal

These actuators are superior to traditional robots in industrial applications such as food packaging, fruit harvesting, space exploration or non-invasive surgery, and provide improved properties in flexibility, lightweight, amplitude and repeatability of motion, ease and cost-effectiveness in fabrication among others. Such 4D/3D printed fabrication methods could also potentially allow for the integrated manufacturing of embedded electronics including sensors (resistive, capacitive, chemical or biological) in elastomeric materials to provide control mechanisms for such miniaturized SPAs.

Image Courtesy of Virtual and Physical Prototyping 21 Journal

4D/3D printing enables the development of such high-resolution microscale functionalities for microscale applications although it comes with its own set of challenges, as the study notes,

“Miniaturising and scaling down the 3D/4D printed SPAs are highly desirable, particularly by adding the micrometer-size functionalities for practical applications in the manipulation of microscale delicate objects, e.g. cells. Yet, such feature should be scalable in all the key components of the SPAs, including the integrated sensors, flexible electronics, and controllers. However, miniaturising the SPAs is constrained by the resolution of 3D printers and challenges in 3D printing such as avoidance of microscale voids and channels.”

DIW, an extrusion-based 3D printing technology using photocurable resins, was used to fabricate a programmable bio-inspired SPA with tunable mechanical properties. The fabrication approach using DIW had advantages over FDM, SLA, SLS, inkjet, and DLP – producing few voids, required variable stiffness and fatigue properties, higher strength and elongation at break. New approaches to 4D printing SPA’s have developed self-exciting vibration capabilities, or incorporated bellow-type and embedded fibre into the 3D printed elastomer matrix. In terms of sustainability, 3D printed SPA’s could be designed using recyclable materials to have lower environmental impact, with optimized parameters to reduce its carbon footprint and waste.

Such research has opened up a wide range of possibilities in the design, automated fabrication, modeling and control of 4D printed SPAs, and with further improvements in materials, will guide the way to the next generation in soft robotic actuators that will enable better performance, customization, new applications, cost-efficiency, and sustainability while also making human-robot interactions safer than ever before.

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Chinese Researchers Design 3D Printed Biomimetic Soft Robotics & Grippers

In the recently published ‘3D printed shape-programmable magneto-active soft matter for biomimetic applications,’ researchers from China explore the development of a high-performance material that transforms quickly from one shape to another as required for specific applications.

Materials scientists continue to be inspired by nature in many of their studies and consequent innovations today, and as 3D printing morphs into 4D printing with shapes that deform and then return to their original shape, digital fabrication itself continues to expand. Most of these materials and consequent deformation are driven by external forces in the environment such as temperature or moisture and can be used as complex geometries for applications like medicine, robotics, and more.

In this study, the authors examine the use of magnetic field control and magneto-active soft materials (MASMs) as they offer the potential for both soft sensors and actuators. Previous research has been performed with 3D magnetic printing, resulting in the fabrication of both anisotropic composites coupled with magnets.

Shape-programming strategy and manufacturing process of MASMs. (a) The flow chart of shape-programming strategy and a programming case for imitation of inchworm. The deformations are simulated by COMSOL, and the direction of the UMF is indicated by the red arrows. (b) Schematic illustrations of 3D printing and encapsulation. 3D printing is employed for manufacturing the various magnetic structural elements, which are encapsulated by silicone rubber. (c) The photos of the MASM samples with oriented magnetic structural elements. The radius of the disk samples is 10 mm. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

With a new ‘shape-programming strategy,’ the goal for this study was to create stable shapes that transform quickly and are also programmable. The research team put the benefits of 3D printing to work:

“With the advantages of 3D printing, this manufacturing approach enables the magnetic structural elements with any shape, distribution, and orientation to generate anisotropic magnetization profiles. This method allows us to program magnetic moment in the soft matrix, enabling the desired actuation capabilities of the MASMs. The deformation property of shape programmable MASMs have been studied synthetically, and the related physical mechanism has been proposed.”

“With these excellent capabilities, various biomimetic structures (inchworm, manta ray, and soft gripper) can be easily fabricated with walking, swimming and snatching functions under the uniform magnetic field (UMF). This proposed approach can make up for the shortcomings of the existing programming methods and opens new avenues to fully capitalize the potential of MASMs.”

Shape-change mechanisms and deformation performance of MASM strip. (a) Finite element analysis of the oriented magnetic structural elements evaluated by COMSOL. The strength of the applied UMF is 300 mT, and the direction is indicated by the red arrow. The magnetic flux density is indicated by the color legend, and the direction and magnitude of Maxwell’s surface stress tensor are indicated by the direction and logarithmic size of the red arrows. (b) Magnetization curves (magnetic moment per unit mass) of magnetic filament and CIPs. The inserted photos are SEM images of CIPs and magnetic filament, and the scale bars are 2 μm and 0.5 mm respectively. (c) Photographs of the bending deformation of the MASM strip under 0, 100, and 200 mT, and the scale bars are 5 mm. In this case, the magnetic structural elements with a length of 1.5 mm, width of 0.3 mm, and thickness of 4 mm have distributions in SR. (d) Curve of the bending deformation of the MASM strip under increasing and decreasing magnetic flux density, which is controlled by the current in the electromagnet. The deformation is evaluated by the displacement of the central point of the MASM strip. The test schematic is illustrated in Fig. S1e. (e) Cycle test of deformation performance of the MASM strip under transient magnetic field. The time for each cycle is 1.5 s, and it includes the transient increase and decrease of the magnetic field. The transient magnetic field is generated on the basis of the motion of the permanent magnet controlled by a linear motor, as shown in Fig. S1f. (f) Single-cycle curves of bending deformation and transient magnetic field. The response and reset times are marked. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

PLA was mixed at a 6:1 volume ratio with Carbonyl iron particles (CIPs), blended mechanically for 30 minutes, and then added to the extruder of an FDM 3D printer.

“Here, it should be noted that printing magnetic structural elements is just one of the methods for the design of magnetic moment. Adjusting the magnetic moment can also depend on the particle distribution and magnetic domain,” explained the researchers.

Upon 3D printing, however, the magnetic structures were comprised of isotropic ferromagnetic properties due to the uniform dispersion of PLA particles. The team 3D printed samples with a variety of different oriented magnetic structural elements, confirming that these differences did affect mechanical properties of the MASMs.

Ultimately, the researchers were able to create a range of biomimetic structures inspired by nature such as the inchworm, manta ray, and a soft gripping device. Fabricated samples were also inspired by animals such as snakes and mollusks, and the MASM forms were capable of mimicking their structures and movements; however, magnetization was dependent on distribution and orientation of adjacent magnetic structural elements—meaning that overall magnetics must be considered for required efficiency.

Various shape-programmable MASMs with two-dimensional shape change under
applied magnetic fields for biomimetic imitation. (a) Photographs of snake, starfish, and brittle star. (b) Finite element simulation of programmed shapes via COMSOL. The magnetic flux density is indicated by the color. (c) Two-dimensional shape changes of MASMs under applied magnetic fields. The intensity of the horizontal UMF is 200 mT, and the direction is indicated by the arrow. For different programmed shapes, the magnetic structural elements with a length of 1.5 mm, a width of 0.3 mm, and a thickness of 4 mm have different distributions in SR. All scales are 10 mm. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this
article.)

Design of soft robots and actuator on the basis of shape-programmable MASMs. (a) Walking motion of the inchworm-like soft robot on serration plate. The bending of the robot is driven by the UMF, and it is restored by the coupling of gravity and elastic forces. The white scale bar is 10 mm. (b) Swimming of the manta ray-like soft robot under water. The swing of the swimming robot is also driven by the UMF. The white scale bar is 10 mm. (c) Grab and release of the soft gripper. The gripping action is driven by the UMF, and the weight of the cylindrical object is 15.3 g. The white scale bar is 20 mm. In these cases, the intensity of the UMF is 300 mT, and the direction is as indicated by the arrow.

The sample structures, ‘successfully fabricated,’ exhibited potential for functionality in exercises such as locomotion, swimming, and grabbing. They also displayed the desired mechanical properties with stability and accuracy in shape-changing—ensuring performance required for the future design of actuators and soft robotic innovations.

Upon factoring in the low density, ‘excellent flexibility,’ and suitable properties for actuation, the team continued to move forward with their project, making soft robots and actuators:

The inchworm design translated into a soft robot able to ‘walk’ on a serration plate created by the researchers.
The manta ray design inspired another soft robot with ‘muscles and wingspan’ made of both MASMs and SR. It was even able to swim underwater.
The soft gripper functioned beyond that of conventional similar devices, with grab-and-release manipulated by magnetic actuation.

“This work simply uses uniform magnetic field (UMF) as the actuation only, but more complex actuation behaviors can also be generated by using the gradient magnetic field. The proposed approach opens new avenues to fully capitalize the potential of MASMs, allowing researchers to develop a wide range of soft actuators that are critical in soft robotics, medical care, and bionics applications,” concluded the authors upon completing their study.

Scientists have always had a history of being inspired by nature, and this has played a fascinating role in the progression of 3D printing as biomimetics have been the force behind new prosthetics, innovative architectural structures, drone technology, and more.

What do you think of this news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com.

[Source / Images: ‘3D printed shape-programmable magneto-active soft matter for biomimetic applications’]

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Harvard and Caltech 3D prints self-folding soft robots inspired by origami

Researchers from Harvard University and the California Institute of Technology have developed origami-inspired soft robotic systems that adopts task-specific configurations on demand. Of the systems fabricated is a 3D printed “Rollbot” that assembles into a pentagonal prism and self-rolls in programmed responses to thermal stimuli. Another 3D printed device is a self-twisting origami polyhedron that exhibits […]

3D Printed Cellular Fingers Offer Material Balance Required for Modern Robotics

In ‘Toward a Smart Compliant Robotic Gripper Equipped with 3D-Designed Cellular Finger s,’ authors Manpreet Kaur and Woo Soo Kim delve into the world of combining 3D printing and robotics. Their recently published paper focuses on the design of a robotic structure with deformable cellular structures that are easy to fabricate.

The conventional metal robot or robotic components are increasingly being upstaged by softer materials that offer more versatility for industrial applications. Not only that, many of these new materials are able to morph to their environment, affected by environments such as temperature or moisture. Kaur and Kim remind us that many of these innovations are originally inspired by nature, such as the movement of and the frictional properties of the snake.

Design and fabrication of multi‐material auxetic structure: A) 2D sketch of the re‐entrant honeycomb unit cell with defined parameters. B) Schematic demonstration of filament extrusion–based multi‐material 3D printing. C) Different designs of auxetic unit cells with two important parameters, α (the ratio of length of vertical strut h by re‐entrant strut l) and θ (the re‐entrant angle), defined in the sketch (A). D) The CAD image of the 3D re‐entrant honeycomb structure made by joining two 2D structures at 90°. The single tone gray color indicates the usage of a single material that is a TPU‐based flexible material. E) A dual‐material‐based auxetic unit cell where the re‐entrant struts (red) made of flexible material and the vertical struts (gray) made of rigid material. F) Different designs of dual‐material‐based auxetic unit cell, where the joints (gray) are made of flexible material and the rest of the portion of the struts (blue) are printed with the combination of both flexible and rigid material with equal proportion.

In creating soft robotics, however, there is the challenge of finding a balance between flexibility and structural stiffness and incorporating electronics which usually consist of a variety of different bulky systems. The cellular finger noted in this research can be made with embedded sensors in the fingertips, allowing for a significant gripping force of 16N, and the ability to pick up numerous objects—and acting as an example of more complex architectures for better functionality and performance overall.

“Stretching‐dominated cellular solids, such as octet, octahedral, and so on, show higher initial yield strength compared with bending‐dominated foamed materials, which is due to their different layout of structural components and makes them better alternatives for lightweight structural applications. One such unique spatially arranged structure produces a negative Poisson’s ratio (NPR); these are called auxetics. Like other types of mechanical metamaterials, the NPR of auxetics is generally a direct consequence of the topology, where the joints rotate to move the structure,” state the researchers.

Characterization of 3D printed auxetic structures: A) Compressed samples from the design with α = 1.5 and θ = −20°. Three different material distributions in the unit cell (single, dual 1, and dual 2 designs) are studied. Images were captured for each sample at 0%, 20%, and 40% strains. B) Stress–strain graph of three samples with different combinations of α = 1.5, 2 and θ = −20°, −30 ° for designs (single, dual 1, and dual 2). The legends read as “a” for alpha, “t” for theta, and S, D1, D2 for single, dual 1, and dual 2, respectively. C) Finite element analysis (FEA) simulation analysis of compressed auxetic unit cell to study the different stress distributions in the elastic region for the three different designs. The color code is kept constant and is defined next to each image. The corresponding elastic curves from experiment and simulation are compared for each case. D) The cellular finger is designed using the rigid stretching‐dominated octet structure for the main body and using chosen auxetic structure (α = 1.5 and θ = −20°) with dual 2 designs for the joints.

NPR materials are also able to deform and show ‘compliant-bending behavior.’ In this research project, Kaur and Kim used honeycomb structures—again, inspired by nature—examining their ability to absorb energy and bend. These re-entrant structures are more easily translated to the 3D realm and allowed the authors to experiment regarding parameters and resulting cell properties. The end goal was to achieve deformity, along with suitable durability and energy efficiency.

With the use of porous cellular materials meant to meet the balance of both softness and flexibility and the need for firmness also, the researchers were able to roll their knowledge of materials, manufacturing, and robotics into one—along with 3D printing and the use of triple materials. The robotic gripper finger was made up of the following lightweight parts:

Three octet segments
Two auxetic joints (mimicking human bones and joints)
Integrated pressure sensor on the fingertip

The following materials were used for 3D printing the single, dual 1, and dual 2 designs: SemiFlex, PLA, and carbon fiber reinforced PLA (CFRPLA). The porosity level allowed for the sought-after balance in a lightweight structure as well as offering the proper rigidity for various gripping functions. The overall design was also responsible for the system of fingers able to deform as needed, in tune with objects and their specific shapes—while the fingertip sensors monitoring the environment.

Mechanical properties of the samples from compression test

“Our architectured robotic finger is a starting point of cellular design concept. Therefore, there is a lot of room for further research in this topic. Design of other mechanical metamaterials has lots of opportunities, so other lattice structures can be investigated to tune additional mechanical deformation functionality in the robotic finger,” concluded the researchers.

“The optimization of sensor design and addition of other sensors can also be investigated to achieve its ubiquitous performance. This compliant robotic design with metamaterial body can prove to enhance the functionality and durability of robotic bodies for prosthetic or industrial applications, thus developing new generation of robotic systems with better performance and greater adaptability in a variety of tasks.”

Robotics and 3D printing are paired up often these days, in projects ranging from uses in furniture manufacturin g to soft robotics, and more. What do you think of this news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com.

Auxetic unit cell designs based on different α and θ parameters

[Source / Images: ‘Toward a Smart Compliant Robotic Gripper Equipped with 3D-Designed Cellular Finger s’]

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Aether and UCLA Partner to Develop 3D Printed Artificial Muscles

Robots have come a long way, moving past their traditional image of stiff metal machines and becoming something much more varied and sophisticated. Soft robotics is an expanding field, leading to everything from virtual reality applications to artificial muscle. Artificial muscles are a promising development, with applications that include prosthetics, implants, drug delivery systems, and other medical devices, and they are the focus of a new collaboration between UCLA and bioprinting company Aether.

Aether and UCLA’s Henry Samueli School of Engineering will work together to develop technologies for faster, easier fabrication of soft artificial muscles and other multi-material structures. Aether will work on optimizing the Aether 1 bioprinter and its computer vision capabilities to automate the process of 3D printing soft robotic devices, improve print quality and ease of use.

Aether recently upgraded its automatic offset calibration system to make embedding conductive materials easier than ever before, using computer vision to automatically calculate precise offsets for multiple tools and tool types. This allows users to extrude multiple materials side by side without overlapping or gaps and enables conductive materials like graphene or silver nanoparticles to be printed directly into robotic devices, eliminating the need for wires.

Partnering with UCLA is personal for Aether CEO Ryan Franks, who caught pneumonia 10 years ago and was hospitalized at UCLA Hospital. He was healed thanks to a lifesaving procedure performed by Dr. Abbas Ardehali. The procedure was called VATS, or video-assisted thoracoscopic surgery, and it sparked Franks’ interest in medical technology, leading directly to the founding of Aether.

“Working on technology with UCLA is something I’ve dreamed of for a long time,” said Franks. “There’s no one better when it comes to robotics, and the fact that UCLA faculty saved my life makes this collaboration incredibly special.”

Aether Director of Engineering Marissa Buell (a fellow UCLA Engineering alumni), CEO Ryan Franks, and students at UCLA with Aether 1 beta unit [Image: Aether]

UCLA researchers will also join a collaboration between Aether and Harvard Medical School and will receive pre-release access to Aether’s upcoming advanced visualization AI software, featuring ASAR (Automatic Segmentation and Reconstruction) technology. ASAR allows users to view medical images like CT scans or X-rays. They can select a desired organ or tissue type and quickly obtain a segmented organ 3D file. The system simplifies medical analysis and saves time, allowing surrounding anatomy to be quickly removed for a clearer focus.

In 2019, Aether will launch software that will allow users to create 3D printable organs from medical images with the push of a button, and according to the company, it will be priced lower than competing software. Aether also states that the software is faster than that of competitors, taking only seconds to do what previously has taken hours or even days.

Aether also released a new video today that shows the Aether 1 printing an analog of a microfluidic device, using eight tools in one print. First, two FDM extruders print a substrate in two colors of PLA. Then, two colors of silicone are printed on the substrate as aboveground wells, which are then cured by the UV LED. A laser engraves two thin grooves in the PLA substrate to serve as belowground liquid channels. Two microvalves, each filled with a different color of water, then jet liquid into the two aboveground wells and belowground channels. You can see the video below:

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