We thank the Dalio Institute of Cardiovascular Imaging for funding this work.

1. Smoothing the TPU sheets by heat pressing
<ol>
	<li>Calibrate a force sensor to be used in the heat press.
	<ol>
		<li>Sandwich the force sensor between two layers of silicone (50 mm x 50 mm x 3 mm thick). Place the force sensor and silicone layers between the compression platens/anvils of the tensile machine. Decrease the distance between the platens by turning the knob of the heat press clockwise and write down the force and resistance of the sensor.</li>
		<li>Measure the area of the sensor using a digital caliper and divide the force values by the measured area to obtain the pressure data. Fit a linear line to the pressure versus resistance data using a spreadsheet to calibrate the sensor.</li>
	</ol>
	</li>
	<li>Place the force sensor inside the heat press and turn the pressure knob until a pressure of ~200 kPa is read from the sensor.</li>
	<li>Wear gloves to avoid any contamination of the TPU films.</li>
	<li>Cut four layers of TPU with scissors or a laser cutter to fit the heat press plates (30 mm x 30 mm). Position the four sheets so all four edges are aligned.</li>
	<li>Place the TPU sheets inside the heat press.</li>
	<li>Set the temperature of the heat press to ~200 &#176;F (~93 &#176;C). Close the heat press fully.</li>
	<li>Keep the films inside the heat press for 10 min. Open the heat press and remove the laminated TPU films to be laser cut in step 3.12.</li>
</ol>
2. Finding the optimal laser parameters
<ol>
	<li>As described in section 1, heat press two layers of TPU.</li>
	<li>Using computer-aided design (CAD) software, design a square with 20 mm sides and a rectangle of 4 mm x 8 mm that will act as the inlet of the square balloon.</li>
	<li>Laser cut/weld the square pattern from step 2.2 out of the TPU layers from step 2.1 using the following settings in the laser cutter software: set pulses per inch (PPI) to 500, vary the power from 10% to 100%, and for each value of power vary the speed from 10% to 100%.</li>
	<li>Cut the end of the inlet of the square balloon with scissors.</li>
	<li>Insert a needle inside the square balloon inlet, apply glue (Table of Materials) around it, and wrap the polytetrafluoroethene (PTFE) tape around the connection. 
	NOTE: After 5 min it is ready to use.</li>
	<li>Identify the average burst pressure of the square balloon by inflating it with a precise fluid dispenser.</li>
	<li>Increase the pressure of the balloon using the precise fluid dispenser until it bursts. Measure and write down the burst pressure. Repeat this step 5x and obtain the average burst pressure.</li>
	<li>Repeat steps 2.1&#8722;2.7 for the full range of power and speed values and identify the maximum burst pressure of the square balloon and its associated power and speed values as the optimal parameters for the laser machine.</li>
</ol>
3. Fabricating the actuators by laser cutting/welding
<ol>
	<li>Design the desired actuator pattern using CAD software. 
	NOTE: AutoCAD 2017 is used in this protocol.</li>
	<li>Select the entire design in the CAD software by highlighting all segments of the design.</li>
	<li>In the task bar under the Properties section, change the line weight to 0 mm for the software to print successfully to the laser cutter.</li>
	<li>From the taskbar, select Print. Change the printer name to &#8220;VLS2.30&#8221; in the menu.</li>
	<li>In the Printer Settings, choose the paper size as User-defined Landscape.</li>
	<li>In the Plot Scale section, deselect the Fit to Paper Option and then scale the image size as 1 mm = one unit of length.</li>
	<li>In the Plot Offset (Origin Set to Printable Area) check the Center the Plot option.</li>
	<li>Turn on the air filter by pressing the power button.</li>
	<li>Turn on the laser cutter by pressing the power button or by clicking on the power icon on the Universal Laser System Control Panel software.</li>
	<li>In the Setting option, set the speed = 60%, PPI = 500, and power = 80%. 
	NOTE: These parameters may need to be changed based on the specific laser power of the system being used.</li>
	<li>Using the Focus View tool, move the laser pointer to the left top corner and bottom right corner of the pattern to make sure the whole pattern fits inside the laminated TPU films (30 mm x 30 mm) made in step 1.10.</li>
	<li>To focus the laser machine, move the lens carriage to the middle of the table. Place the focus tool on the table and move the table up until the top of the focus tool touches the front of the lens carriage. Then, move the table up slowly until the lens carriage hits the notch of the focus tool and bumps it forward. 
	NOTE: The laser is focused and ready for use with the parameters in 3.11.</li>
	<li>Without changing the position of the TPU sheet, run the laser again, but decrease the speed = 55%, increase the power = 85%, and keep PPI = 500.</li>
	<li>Perform a third run of the laser to ensure there are no leaks in the actuator. Set the speed = 50%, increase the power = 90%, and keep PPI = 500.</li>
</ol>
4. Bonding stainless steel dispensing needles with a Luer lock connection
<ol>
	<li>Cut the end of the balloon actuator inlet with scissors.</li>
	<li>Insert a needle inside the balloon actuator inlet, apply glue around it, and wrap the PTFE tape around the connection. 
	NOTE: After 5 min it is ready to use.</li>
</ol>
5. Characterization of the soft actuators
<ol>
	<li>Mount a camera over the actuator with a sufficient distance so that the actuator is in full view within the camera in both its pressurized and unpressurized states.</li>
	<li>Hold the actuator in an orientation such that its deflection upon pressurization is orthogonal to the camera.</li>
	<li>Increase the pressure of the actuator with a precise fluid dispenser until it deflects into its full range without bursting. Assume the full range as the maximum deflection of the actuator without any plastic deformation or leakage or bursting due to overinflation.</li>
	<li>Increase the actuator pressure until it reaches ~20% of its full range and write down the pressure.</li>
	<li>Take a picture of the actuator using the camera from step 5.1, and then use an image processing software (e.g., imageJ) to measure the X- and Y-coordinates of the tip of the actuator in the image.</li>
	<li>Repeat steps 5.4 and 5.5 until reaching the full range of actuator deflection.</li>
	<li>Plot an X-Y graph of the actuator&#8217;s deflection versus the inflation pressure using a plotting software.</li>
</ol>

<ol>
	<li>Moghadam, A. A. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser+Cutting+as+a+Rapid+Method+for+Fabricating+Thin+Soft+Pneumatic+Actuators+and+Robots.">Laser Cutting as a Rapid Method for Fabricating Thin Soft Pneumatic Actuators and Robots.</a> Soft Robotics. 5 (4), 443-451 (2018).</li><li>Paek, J. W., Cho, I., Kim, J. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microrobotic+tentacles+with+spiral+bending+capability+based+on+shape-engineered+elastomeric+microtubes.">Microrobotic tentacles with spiral bending capability based on shape-engineered elastomeric microtubes.</a> Scientific Reports. 5, (2015).</li><li>Gorissen, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flexible+pneumatic+twisting+actuators+and+their+application+to+tilting+micromirrors.">Flexible pneumatic twisting actuators and their application to tilting micromirrors.</a> Sensors and Actuators A-Physical. 216, 426-431 (2014).</li><li>Gorissen, B., De Volder, M., De Greef, A., Reynaerts, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Theoretical+and+experimental+analysis+of+pneumatic+balloon+microactuators.">Theoretical and experimental analysis of pneumatic balloon microactuators.</a> Sensors and Actuators A-Physical. 168 (1), 58-65 (2011).</li><li>Jeong, O. C., Konishi, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=All+PDMS+pneumatic+microfinger+with+bidirectional+motion+and+its+application.">All PDMS pneumatic microfinger with bidirectional motion and its application.</a> Journal of Microelectromechanical Systems. 15 (4), 896-903 (2006).</li><li>Konishi, S., Shimomura, S., Tajima, S., Tabata, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Implementation+of+soft+microfingers+for+a+hMSC+aggregate+manipulation+system.">Implementation of soft microfingers for a hMSC aggregate manipulation system.</a> Microsystems &amp; Nanoengineering. 2, (2016).</li><li>Lu, Y. W., Kim, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microhand+for+biological+applications.">Microhand for biological applications.</a> Applied Physics Letters. 89 (16), (2006).</li><li>Ikeuchi, M., Ikuta, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+Pressure-Driven+Micro+Active+Catheter+using+Membrane+Micro+Emboss+Following+Excimer+Laser+Ablation+(MeME-X)+Process.">Development of Pressure-Driven Micro Active Catheter using Membrane Micro Emboss Following Excimer Laser Ablation (MeME-X) Process.</a> 2009 IEEE International Conference on Robotics and Automation. , (2009).</li><li>Sanan, S., Lynn, P. S., Griffith, S. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pneumatic+Torsional+Actuators+for+Inflatable+Robots.">Pneumatic Torsional Actuators for Inflatable Robots.</a> Journal of Mechanisms and Robotics. 6 (3), 031003 (2014).</li><li>Veale, A. J., Xie, S. Q., Anderson, I. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modeling+the+Peano+fluidic+muscle+and+the+effects+of+its+material+properties+on+its+static+and+dynamic+behavior.">Modeling the Peano fluidic muscle and the effects of its material properties on its static and dynamic behavior.</a> Smart Materials and Structures. 25 (6), (2016).</li><li>Niiyama, R., Rognon, C., Kuniyoshi, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Printable+Pneumatic+Artificial+Muscles+for+Anatomy-based+Humanoid+Robots.">Printable Pneumatic Artificial Muscles for Anatomy-based Humanoid Robots.</a> 2015 IEEE-RAS 15th International Conference on Humanoid Robots (Humanoids). , (2015).</li><li>Niiyama, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pouch+Motors:+Printable+Soft+Actuators+Integrated+with+Computational+Design.">Pouch Motors: Printable Soft Actuators Integrated with Computational Design.</a> Soft Robotics. 2 (2), 59-70 (2015).</li></ol>

The authors have nothing to disclose.

The critical steps in the fabrication of the soft actuators include: i) The 2D CAD design. A proper 2D layout can dictate the deformation of the actuator (e.g. linear, biaxial, bending, and rotational motion). ii) Lamination of the TPU layers. The TPU films are heat pressed before laser cutting to make sure the layers are flat and in conformal contact everywhere. iii) Laser cut/weld. As the final step, the laminated TPU layers are laser cut/welded into soft actuators.
The success rate of the protocol can produce a 100% yield (for example, we have made 20 actuators simultaneously). The primary factor is the lamination step: to obtain the best results, the TPU should be flattened as much as possible before the heat press process. &#160;Examining different regions of the heat press plate with a force sensor may show that the pressure distribution is not uniform. Non-uniform pressure distribution can result in imperfect lamination of the TPU sheets, which in turn results in imperfect laser cutting/welding and leakage. Alternatively, non-uniform heat transfer due to small wrinkles in the TPU film during the laser cutting/welding can cause leakage.
In comparison to the conventional methods, the proposed method has several advantages including: i) Simple 2D design. While the current method only requires 2D CAD designs to laser cut/weld the actuators (various patterns are available1), the conventional fabrication methods based on silicone casting require a 3D mold design. ii) Rapid fabrication. Fabrication time from CAD design to lamination of TPU layers and laser cutting/welding can happen in several minutes, whereas the conventional fabrication method will take several hours. By allowing fabrication of soft devices and soft robots in a single step, without assembly, soft robots and devices can be designed from a combination of different types of actuators, and the CAD model can be laser cut/welded into the final product in a single step without requiring any assembly. For instance, a swimming robot, comprised of four legs each consisting of two types of bending actuators, is fabricated from a 2D CAD design in just a few minutes without requiring any assembly steps, as previously demonstrated1.
As a future direction of this work, different types of thermoplastic materials can be adopted for fabrication of the soft actuators. Generally, these materials need to have elastic behavior to be used as actuators. Application of stiffer thermoplastic material will result in higher burst pressure and higher blocking force of the actuators compared to those previously characterized in Figure S6 of Moghadam et al.1, showing forces up to 0.1 N. Thus, it can extend the application of the actuators to cases where higher blocking force is required, such as exoskeleton suites. &#160;

As a step forward in manufacturing of soft pneumatic actuators, the proposed method illustrates rapid fabrication of ultrathin (~70 &#956;m) pneumatic actuators made of thermoplastic polyurethane (TPU)1. These actuators are particularly useful in applications that require the robots to be lightweight and/or fit within small spaces. Such applications can be envisioned to be transcatheter surgical manipulators, wearable actuators, search and rescue robots, and flying or swimming robots.
The conventional manufacturing method of thin soft pneumatic actuators, which is based on silicone molding, is time consuming (several hours) and very challenging due to the low resolution of the 3D printed molds and difficulties in demolding of thin (less than 0.5 mm) actuators. In particular, fabrication of thin actuators requires the application of specialized tools and methods2.
Microfabrication techniques can be adopted to fabricate thin actuators3,4,5,6,7. Alternatively, Ikeuchi et al. have developed thin pneumatic actuators using membrane micro-embossing8. These methods, although effective, require expensive tools and are time-consuming. Thus, they have limited applications.
Paek et al. demonstrated a simple method for fabrication of small-scale soft actuators using dip-coating of cylindrical templates2. Although effective, there are two issues with widespread application of this method: First, it is not easy to control the thickness of the dip-coated features, and secondly, its application is restricted to a limited number of three-dimensional (3D) designs.
Peano actuators9,10 and pouch motors11,12 have compact two-dimensional (2D) designs that result in thin form factors (i.e., large areas with small thickness). Veale et al. reported development of linear Peano actuators made of reinforced plastic and textile-silicone composites1,8. Niiyama et al. developed pouch motors using thermoplastic films manufactured by heat stamping and heat drawing systems11,12.
While the 2D design of Peano actuators and pouch motors makes them very thin in their unactuated state, upon inflation their zero-volume chamber expands to a relatively large volume, thus limiting their application for operation in limited spaces such as transcatheter therapies or search and rescue missions1. In contrast to these designs, the proposed soft actuators in the current method can actuate with relatively small strains. Thus, even in the actuated state they occupy relatively small spaces1.

<table><tbody><tr><td>Force Sensor</td><td>Omega</td><td>KHLVA-102</td><td>https://www.omega.co.uk/pptst/KHRA-KHLVA-KHA-SERIES.html</td></tr><tr><td>High Precision Dispensers Ultimus I</td><td>Nordson</td><td></td><td>http://www.nordsonefd.com/searchengines/google/en/AirPoweredDispensers/?gclid=CjwKCAjw36DpBRAYEiwAmVVDMPuZ50xXoyzK3gvnghCA7yZUfJg4o9V28yDHKjY5Gs159RJIcMk_choCJIgQAvD_BwE</td></tr><tr><td>Laser Cutter VLS2.30</td><td>Universal Laser System</td><td></td><td>https://www.ulsinc.com/products/platforms/vls2-30</td></tr><tr><td>PowerPress Heat Press</td><td>Power Heat Press</td><td>OX-A1</td><td>https://www.howtoheatpress.com/power-press-15x15-heat-press-review/</td></tr><tr><td>PTFE Thread Sealant tape</td><td>McMaster-Carr</td><td>4934A11</td><td>https://www.mcmaster.com/ptfe-tape</td></tr><tr><td>Stainless Steel Dispensing Needle</td><td>McMaster-Carr</td><td>75165A754</td><td>https://www.mcmaster.com/75165a754</td></tr><tr><td>Super Glue Loctite 409</td><td>Henkel</td><td>229654</td><td>https://www.henkel-adhesives.com/us/en/product/instant-adhesives/loctite_409.html</td></tr><tr><td>Thermoplastic polyurethane Airtech&amp;rsquo;s Stretchlon 200</td><td>ACP Composites</td><td>v-11A</td><td>https://store.acpsales.com/products/3321/stretchlon-200-high-stretch-bag-film-60</td></tr><tr><td>Universal Testing Systems</td><td>Instron</td><td>5943</td><td></td></tr></tbody></table>

rapid manufacturing of thin soft pneumatic actuators and robots

This protocol describes a method for rapid manufacturing of soft pneumatic actuators and robots with an ultrathin form factor using a heat press and a laser cutter machine. The method starts with the lamination of thermoplastic polyurethane (TPU) sheets using a heat press for 10 min at the temperature of ~93 &#176;C. Next, the parameters of the laser cutter machine are optimized to produce a rectangular balloon with maximum burst pressure. Using the optimized parameters, the soft actuators are laser cut/welded three times sequentially. Next, a dispensing needle is attached to the actuator, allowing it to be inflated. The effect of geometrical parameters on the deflection of the actuator are studied systematically by varying the channel width and length. Finally, the performance of the actuator is characterized using an optical camera and a fluid dispenser. Conventional fabrication methods of soft pneumatic actuators based on silicone molding are time consuming (several hours). They also result in strong but bulky actuators, which limits the actuator&#8217;s applications. Moreover, microfabrication of thin pneumatic actuators is both time-consuming and expensive. The proposed manufacturing method in the current work resolves these issues by introducing a fast, simple, and cost-effective fabrication method of ultrathin pneumatic actuators.

To demonstrate the proposed method, we show the fabrication of a single bending actuator. To fabricate this actuator, four sheets of TPU of dimension 25 cm x 25 cm were cut, stacked together, and then smoothed using a heat press (Figure 1A). Following the protocol, the heat press was applied for 10 min at a set temperature of 200 &#176;F. Wrinkles in the laminated sheets can result in issues with bonding during the laser cutting step, therefore ensuring a perfectly smooth surface is critical for reproducible results. For example, Figure 1B shows a resulting lamination that contains wrinkles that will not produce desired results, while Figure 1C shows a resulting lamination that is sufficiently flat to produce the desired results.
The 2D design of the pneumatic actuator was drawn in AutoCAD. This actuator was made simply by drawing a rectangle of 8 mm x 150 mm. A linear pattern of eight lines, each 1.34 mm long, was added to the center of the design with a spacing of 10 mm (highlighted in red in Figure 2). Finally, the opening of the actuator (highlighted in blue in Figure 2) was designed by adding an open-ended rectangle of 4 mm x 8 mm. An AutoCAD file (.dwg) for this sample linear actuator is available in the Supplemental Material.
The laminated four-layer stack of TPU was then placed in the laser cutting machine (Figure 3A) and the 2D design was imported using the software of the laser cutting machine. The Focus tool on the laser cutter verified the fit of the 2D drawing&#8217;s position on the laminated TPU sheets. For a first run, the laser cut was set at speed = 60%, power = 80%, and PPI = 500. Once it was completed, without changing the position of the polyurethane sheets, a second run with new settings was started at speed = 55%, power = 85%, and PPI = 500. The same process was repeated with new settings for a third time at speed = 50%, power = 90%, and PPI = 500. Decreasing the speed and increasing the power exposes the pneumatic actuator to the heat source for a longer time and allows it to melt and bond to ensure a leak-free balloon that can separated from the rest of the TPU sheet easily (Figure 3B). It should be noted that the laser cutter is always simultaneously cutting and welding the TPU; the cutting and welding are not done in separate steps or achieved by different settings.
In order to couple the actuator to an air supply unit, the opening of the actuator was cut with scissors and a stainless steel needle (Figure 4B) was inserted between the second and third layers of the laser-cut actuator. To maintain a leak-free system, the outside of the needle was covered in glue beforehand (Figure 4C). Then the interface of the actuator and stainless steel needle was wrapped tightly with PTFE tape (Figure 4D).
Finally, using a digital fluid dispenser, the pneumatic actuator (Figure 5A) was inflated to a pressure of 5 psi to observe a deflection in the region where the array of lines was designed (Figure 5B).
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/60595/60595fig1.jpg" /> 
Figure 1: Heat pressing sheets. (A) Image of the heat press with the TPU sheets to be laminated. (B) Example image of poorly laminated sheets with excessive wrinkles. (C) Example image of successfully laminated sheets with a smooth surface. <a href="https://www.jove.com/files/ftp_upload/60595/60595fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/60595/60595fig2.jpg" /> 
Figure 2: Actuator design. Image of a CAD drawing used to form a single bending actuator. The bottom design shows the outline of the actuator, the middle design shows a single line added as a bending feature, and the top design shows a complete actuator. The red box highlights the features that form the bending region of the actuator. The blue box highlights the region for connecting a needle for pressurization. <a href="https://www.jove.com/files/ftp_upload/60595/60595fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/60595/60595fig3.jpg" /> 
Figure 3: Laser cutter. (A) Image of the laminated sheets in a laser cutter. (B,C) Image of the actuator to be removed after laser cutting. (C) Image of the actuator. <a href="https://www.jove.com/files/ftp_upload/60595/60595fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/60595/60595fig4.jpg" /> 
Figure 4: Needle connection. Images depicting the steps for connecting a blunt needle (A) to a balloon actuator using glue (B) as an adhesive. The needle is inserted into the narrow end of the actuator, which is opened using scissors (C) and sealed with PTFE tape (D). <a href="https://www.jove.com/files/ftp_upload/60595/60595fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/60595/60595fig5.jpg" /> 
Figure 5: Bending actuator. (A) Image of the actuator in an unpressurized state. (B) Image of the actuator in a pressurized state. <a href="https://www.jove.com/files/ftp_upload/60595/60595fig5large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Supplemental Material.&#160;<a href="https://www.jove.com/files/ftp_upload/60595/JOVE_PAPER.dwg" target="_blank">Please click here to download this file.</a>

Watch this Scientific Journal Video about Rapid Manufacturing of Thin Soft Pneumatic Actuators and Robots at JoVE.com

Rapid Manufacturing of Thin Soft Pneumatic Actuators and Robots

This protocol describes a method for rapid manufacturing of soft pneumatic actuators and robots with a thin form factor. The fabrication method starts with lamination of thermoplastic polyurethane (TPU) sheets followed by laser cutting/welding of a two-dimensional pattern to form actuators and robots.

This protocol describes a method for rapid manufacturing of soft pneumatic actuators and robots with an ultrathin form factor using a heat press and a ...

rapid-manufacturing-of-thin-soft-pneumatic-actuators-and-robots

Research

JoVE Journal

Engineering

7.6K Views.  Weill Cornell Medicine. Deze snelle methode maakt gebruik van een lasersnijder en thermoplastisch polyurethaan om dunne zachte actuatoren te fabriceren met willekeurige geometrie en maten. Het belangrijkste voordeel van de techniek is dat het snel ontwerp en fabricage van meerdere dunne zachte actuatoren en robotprototypes parallel mogelijk maakt. Om een krachtsensor te kalibreren die in de warmtepers moet worden gebruikt, plaatst u eerst een glazen schuif op de krachtsensor en legt u er een gewicht op.Noteer...

Video: Rapid Manufacturing of Thin Soft Pneumatic Actuators and Robots

Synthesis and Characterization of High c-axis ZnO Thin Film by Plasma Enhanced Chemical Vapor Deposition System and its UV Photodetector Application

In this study, zinc oxide (ZnO) thin films with high c-axis (0002) preferential orientation have been successfully and effectively synthesized onto silicon (Si) substrates via different synthesized temperatures by using plasma enhanced chemical vapor deposition (PECVD) system. The effects of different synthesized temperatures on the crystal structure, surface morphologies and optical properties have been investigated. The X-ray diffraction (XRD) patterns indicated that the intensity of (0002) diffraction peak became stronger with increasing synthesized temperature until 400 oC. The diffraction intensity of (0002) peak gradually became weaker accompanying with appearance of (10-10) diffraction peak as the synthesized temperature up to excess of 400 oC. The RT photoluminescence (PL) spectra exhibited a strong near-band-edge (NBE) emission observed at around 375 nm and a negligible deep-level (DL) emission located at around 575 nm under high c-axis ZnO thin films. Field emission scanning electron microscopy (FE-SEM) images revealed the homogeneous surface and with small grain size distribution. The ZnO thin films have also been synthesized onto glass substrates under the same parameters for measuring the transmittance.
For the purpose of ultraviolet (UV) photodetector application, the interdigitated platinum (Pt) thin film (thickness ~100 nm) fabricated via conventional optical lithography process and radio frequency (RF) magnetron sputtering. In order to reach Ohmic contact, the device was annealed in argon circumstances at 450 oC by rapid thermal annealing (RTA) system for 10 min. After the systematic measurements, the current-voltage (I-V) curve of photo and dark current and time-dependent photocurrent response results exhibited a good responsivity and reliability, indicating that the high c-axis ZnO thin film is a suitable sensing layer for UV photodetector application.

We offered a method to directly synthesize high c-axis (0002) ZnO thin film by plasma enhanced chemical vapor deposition. The as-synthesized ZnO thin film combined with Pt interdigitated electrode was used as sensing layer for ultraviolet photodetector, showing a high performance through a combination of its good responsivity and reliability.

In this study, zinc oxide (ZnO) thin films with high c-axis (0002) preferential orientation have been successfully and effectively synthesized onto ...

Fabrication Process of Silicone-based Dielectric Elastomer Actuators

This contribution demonstrates the fabrication process of dielectric elastomer transducers (DETs). DETs are stretchable capacitors consisting of an elastomeric dielectric membrane sandwiched between two compliant electrodes. The large actuation strains of these transducers when used as actuators (over 300% area strain) and their soft and compliant nature has been exploited for a wide range of applications, including electrically tunable optics, haptic feedback devices, wave-energy harvesting, deformable cell-culture devices, compliant grippers, and propulsion of a bio-inspired fish-like airship. In most cases, DETs are made with a commercial proprietary acrylic elastomer and with hand-applied electrodes of carbon powder or carbon grease. This combination leads to non-reproducible and slow actuators exhibiting viscoelastic creep and a short lifetime. We present here a complete process flow for the reproducible fabrication of DETs based on thin elastomeric silicone films, including casting of thin silicone membranes, membrane release and prestretching, patterning of robust compliant electrodes, assembly and testing. The membranes are cast on flexible polyethylene terephthalate (PET) substrates coated with a water-soluble sacrificial layer for ease of release. The electrodes consist of carbon black particles dispersed into a silicone matrix and patterned using a stamping technique, which leads to precisely-defined compliant electrodes that present a high adhesion to the dielectric membrane on which they are applied.

This manuscript shows the fabrication process for the manufacture of dielectric elastomer soft actuators based on silicone membranes. The three key stages of production are presented in detail: blade casting of thin silicone membranes; pad printing of compliant electrodes; and the assembly of all the components.

This contribution demonstrates the fabrication process of dielectric elastomer transducers (DETs). DETs are stretchable capacitors consisting of an ...

SSVEP-based Experimental Procedure for Brain-Robot Interaction with Humanoid Robots

Brain-Robot Interaction (BRI), which provides an innovative communication pathway between human and a robotic device via brain signals, is prospective in helping the disabled in their daily lives. The overall goal of our method is to establish an SSVEP-based experimental procedure by integrating multiple software programs, such as OpenViBE, Choregraph, and Central software as well as user developed programs written in C++ and MATLAB, to enable the study of brain-robot interaction with humanoid robots.
This is achieved by first placing EEG electrodes on a human subject to measure the brain responses through an EEG data acquisition system. A user interface is used to elicit SSVEP responses and to display video feedback in the closed-loop control experiments. The second step is to record the EEG signals of first-time subjects, to analyze their SSVEP features offline, and to train the classifier for each subject. Next, the Online Signal Processor and the Robot Controller are configured for the online control of a humanoid robot. As the final step, the subject completes three specific closed-loop control experiments within different environments to evaluate the brain-robot interaction performance.
The advantage of this approach is its reliability and flexibility because it is developed by integrating multiple software programs. The results show that using this approach, the subject is capable of interacting with the humanoid robot via brain signals. This allows the mind-controlled humanoid robot to perform typical tasks that are popular in robotic research and are helpful in assisting the disabled.

The overall goal of this method is to establish an SSVEP-based experimental procedure by integrating multiple software programs to enable the study of brain-robot interaction with humanoid robots, which is prospective in assisting the sick and elderly as well as performing unsanitary or dangerous jobs.

Brain-Robot Interaction (BRI), which provides an innovative communication pathway between human and a robotic device via brain signals, is prospective in ...

Free-form Light Actuators &#8212; Fabrication and Control of Actuation in Microscopic Scale

Liquid crystalline elastomers (LCEs) are smart materials capable of reversible shape-change in response to external stimuli, and have attracted researchers&#39; attention in many fields. Most of the studies focused on macroscopic LCE structures (films, fibers) and their miniaturization is still in its infancy. Recently developed lithography techniques, e.g., mask exposure and replica molding, only allow for creating 2D structures on LCE thin films. Direct laser writing (DLW) opens access to truly 3D fabrication in the microscopic scale. However, controlling the actuation topology and dynamics at the same length scale remains a challenge.
In this paper we report on a method to control the liquid crystal (LC) molecular alignment in the LCE microstructures of arbitrary three-dimensional shape. This was made possible by a combination of direct laser writing for both the LCE structures as well as for micrograting patterns inducing local LC alignment. Several types of grating patterns were used to introduce different LC alignments, which can be subsequently patterned into the LCE structures. This protocol allows one to obtain LCE microstructures with engineered alignments able to perform multiple opto-mechanical actuation, thus being capable of multiple functionalities. Applications can be foreseen in the fields of tunable photonics, micro-robotics, lab-on-chip technology and others.

Here, we fabricate 3D polymeric micro/nano structures in which both the shape and the molecular alignment can be engineered with nanometer scale accuracy by the use of direct laser writing. Light induced deformation of several types of liquid crystalline elastomer microstructures can be controlled in the microscopic scale.

Liquid crystalline elastomers (LCEs) are smart materials capable of reversible shape-change in response to external stimuli, and have attracted ...

Digital Printing of Titanium Dioxide for Dye Sensitized Solar Cells

Silicon solar cell manufacturing is an expensive and high energy consuming process. In contrast, dye sensitized solar cell production is less environmentally damaging with lower processing temperatures presenting a viable and low cost alternative to conventional production. This paper further enhances these environmental credentials by evaluating the digital printing and therefore additive production route for these cells. This is achieved here by investigating the formation and performance of a metal oxide photoelectrode using nanoparticle sized titanium dioxide. An ink-jettable material was formulated, characterized and printed with a piezoelectric inkjet head to produce a 2.6 &#181;m thick layer. The resultant printed layer was fabricated into a functioning cell with an active area of 0.25 cm2 and a power conversion efficiency of 3.5%. The binder-free formulation resulted in a reduced processing temperature of 250 &#176;C, compatible with flexible polyamide substrates which are stable up to temperatures of 350 &#730;C. The authors are continuing to develop this process route by investigating inkjet printing of other layers within dye sensitized solar cells.

This paper investigates the suitability of inkjet printing for the manufacturing of dye-sensitized solar cells. A binder-free TiO2 nanoparticle ink was formulated and printed onto a FTO glass substrate. The printed layer was fabricated into a cell with an active area of 0.25 cm2 and an efficiency of 3.5%.

Silicon solar cell manufacturing is an expensive and high energy consuming process. In contrast, dye sensitized solar cell production is less ...

Fabrication of Soft Pneumatic Network Actuators with Oblique Chambers

Soft pneumatic network actuators have become one of the most promising actuation devices in soft robotics which benefits from their large bending deformation and low input. However, their monotonous bending motion form in two-dimensional (2-D) space keeps them away from wide applications. This paper presents a detailed fabrication method of soft pneumatic network actuators with oblique chambers, to explore their motions in three-dimensional (3-D) space. The design of oblique chambers enables actuators with tunable coupled bending and twisting capabilities, which gives them the possibility to move dexterously in flexible manipulators, to become biologically inspired robots and medical devices. The fabrication process is based on the molding method, including the silicone elastomer preparation, chamber and base parts fabrication, actuator assembly, tubing connections, checks for leaks, and actuator repair. The fabrication method guarantees the rapid manufacturing of a series of actuators with only a few modifications in the molds. The test results show the high quality of the actuators and their prominent bending and twisting capabilities. Experiments of the gripper demonstrate the advantages of the development in adapting to objects with different diameters and providing sufficient friction.

Here we present a fabrication method of soft pneumatic network actuators with oblique chambers. The actuators are capable of generating coupled bending and twisting motions, which broadens their application in soft robotics.

Soft pneumatic network actuators have become one of the most promising actuation devices in soft robotics which benefits from their large bending ...

Design and Fabrication of an Elastomeric Unit for Soft Modular Robots in Minimally Invasive Surgery

In recent years, soft robotics technologies have aroused increasing interest in the medical field due to their intrinsically safe interaction in unstructured environments. At the same time, new procedures and techniques have been developed to reduce the invasiveness of surgical operations. Minimally Invasive Surgery (MIS) has been successfully employed for abdominal interventions, however standard MIS procedures are mainly based on rigid or semi-rigid tools that limit the dexterity of the clinician. This paper presents a soft and high dexterous manipulator for MIS. The manipulator was inspired by the biological capabilities of the octopus arm, and is designed with a modular approach. Each module presents the same functional characteristics, thus achieving high dexterity and versatility when more modules are integrated. The paper details the design, fabrication process and the materials necessary for the development of a single unit, which is fabricated by casting silicone inside specific molds. The result consists in an elastomeric cylinder including three flexible pneumatic actuators that enable elongation and omni-directional bending of the unit. An external braided sheath improves the motion of the module. In the center of each module a granular jamming-based mechanism varies the stiffness of the structure during the tasks. Tests demonstrate that the module is able to bend up to 120&#176; and to elongate up to 66% of the initial length. The module generates a maximum force of 47 N, and its stiffness can increase up to 36%.

This paper describes the design and fabrication of a soft unit for surgical manipulators. The base module includes three flexible fluidic actuators to achieve omnidirectional bending and elongation, and a granular jamming-based mechanism to enable stiffness control. A complete mechanical characterization is also reported.

In recent years, soft robotics technologies have aroused increasing interest in the medical field due to their intrinsically safe interaction in ...

Bioengineering

Rod-based Fabrication of Customizable Soft Robotic Pneumatic Gripper Devices for Delicate Tissue Manipulation

Soft compliant gripping is essential in delicate surgical manipulation for minimizing the risk of tissue grip damage caused by high stress concentrations at the point of contact. It can be achieved by complementing traditional rigid grippers with soft robotic pneumatic gripper devices. This manuscript describes a rod-based approach that combined both 3D-printing and a modified soft lithography technique to fabricate the soft pneumatic gripper. In brief, the pneumatic featureless mold with chamber component is 3D-printed and the rods were used to create the pneumatic channels that connect to the chamber. This protocol eliminates the risk of channels occluding during the sealing process and the need for external air source or related control circuit. The soft gripper consists of a chamber filled with air, and one or more gripper arms with a pneumatic channel in each arm connected to the chamber. The pneumatic channel is positioned close to the outer wall to create different stiffness in the gripper arm. Upon compression of the chamber which generates pressure on the pneumatic channel, the gripper arm will bend inward to form a close grip posture because the outer wall area is more compliant. The soft gripper can be inserted into a 3D-printed handling tool with two different control modes for chamber compression: manual gripper mode with a movable piston, and robotic gripper mode with a linear actuator. The double-arm gripper with two actuatable arms was able to pick up objects of sizes up to 2 mm and yet generate lower compressive forces as compared to elastomer-coated and non-coated rigid grippers. The feasibility of having other designs, such as single-arm or hook gripper, was also demonstrated, which further highlighted the customizability of the soft gripper device, and it's potential to be used in delicate surgical manipulation to reduce the risk of tissue grip damage.

This protocol describes a rod-based approach, combining 3D-printing and soft lithography techniques for fabricating the soft gripper devices. This approach eliminates the need for an external air source by incorporating a chamber component and reduces the chance of occlusion during the sealing process, particularly for miniaturized pneumatic channels.

Soft compliant gripping is essential in delicate surgical manipulation for minimizing the risk of tissue grip damage caused by high stress concentrations ...

Fabrication of Carbon-Based Ionic Electromechanically Active Soft Actuators

Ionic electromechanically active capacitive laminates are a type of smart material that move in response to electrical stimulation. Due to the soft, compliant and biomimetic nature of this deformation, actuators made of the laminate have received increasing interest in soft robotics and (bio)medical applications. However, methods to easily fabricate the active material in large (even industrial) quantities and with a high batch-to-batch and within-batch repeatability are needed to transfer the knowledge from laboratory to industry. This protocol describes a simple, industrially scalable and reproducible method for the fabrication of ionic carbon-based electromechanically active capacitive laminates and the preparation of actuators made thereof. The inclusion of a passive and chemically inert (insoluble) middle layer (e.g., a textile-reinforced polymer network or microporous Teflon) distinguishes the method from others. The protocol is divided into five steps: membrane preparation, electrode preparation, current collector attachment, cutting and shaping, and actuation. Following the protocol results in an active material that can, for example, compliantly grasp and hold a randomly shaped object as demonstrated in the article.

This article describes a fast and simple manufacturing process of ionic electromechanically active composite materials for actuators in biomedical, biomimetic and soft robotics applications. The key fabrication steps, their importance for the actuators&#39; final properties, and some of the main characterization techniques are described in detail.

Ionic electromechanically active capacitive laminates are a type of smart material that move in response to electrical stimulation. Due to the soft, ...

Manufacturing, Control, and Performance Evaluation of a Gecko-Inspired Soft Robot

This protocol presents a method for manufacturing, control, and evaluation of the performance of a soft robot that can climb inclined flat surfaces with slopes of up to 84&#176;. The manufacturing method is valid for the fast pneunet bending actuators in general and might, therefore, be interesting for newcomers to the field of actuator manufacturing. The control of the robot is achieved by means of a pneumatic control box that can provide arbitrary pressures and can be built by only using purchased components, a laser cutter, and a soldering iron. For the walking performance of the robot, the pressure-angle calibration plays a crucial role. Therefore, a semi-automated method for the pressure-angle calibration is presented. At high inclines (&#62; 70&#176;), the robot can no longer reliably fix itself to the walking plane. Therefore, the gait pattern is modified to ensure that the feet can be fixed on the walking plane.

This protocol provides a detailed list of steps to be performed for the manufacturing, control and evaluation of the climbing performance of a gecko-inspired soft robot.

This protocol presents a method for manufacturing, control, and evaluation of the performance of a soft robot that can climb inclined flat surfaces with ...

Rapid Manufacturing of Thin Soft Pneumatic Actuators and Robots

Samenvatting

Meer video's verkennen