This work was supported by the National Natural Science Foundation of China under Grant 51622506 and the Science and Technology Commission of Shanghai Municipality under Grant 16JC1401000.

NOTE: The protocol provides the fabrication procedures of a soft pneumatic network actuator. Before the fabrication procedure, a set of molds and several actuator-tubing connectors, which are designed with computer-aided design (CAD) software must be 3-D-printed in advance. The molds are shown in Figure 1B.
1. Silicone Elastomer Preparation
<ol>
	<li>Weigh 5 g of silicone elastomer part B and 45 g of part A [9:1 (A:B) parts by weight] in the sam...

<ol>
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The paper presents a method protocol to guide the fabrication of soft pneumatic network actuators with oblique chambers. Following the protocol, one actuator can be fabricated independently within 3 h. The key steps in the protocol can be summarized as follows. (i) The silicone elastomer is prepared in proportion and mixed well. (ii) The silicone elastomer is poured into the mold for the fabrication of the chamber part and the base part. (iii) The bubbles on the exposed surface are pierced and any excess silicone elastom...

Soft pneumatic actuators (SPAs) are soft devices that can be actuated by the simple input of air pressure1,2. They can be fabricated with diverse materials, such as silicone elastomers3, fabrics4, shape-memory polymers5, and dielectric elastomers6. Researchers have benefited from their nature of compliance, dexterous motions, and simple fabrication methods7, such that SPAs have become one of the most promising devices for soft robotics applications8,9. SPAs can realize various sophisticated motions, such as creeping10, rotation11, and rolling12 based on various types of deformation, including extending, expanding, bending, and twisting13,14. To be able to make different types of motions, SPAs are designed in different structures, such as a linear body with parallel channels15, a monolithic chamber with fiber-reinforcements16, and networks of repeated sub-chambers17. Among them, the SPAs with networks of repeated sub-chambers, the soft pneumatic network actuators, are widely employed because they can generate large deformations under a relatively low input pressure. However, in most of the previous designs, this type of actuators can only generate bending motions in 2-D space, which greatly limits their applications.
A soft pneumatic network actuator consists of a linearly arranged group of chambers connected by an internal channel. Each cubic chamber contains a pair of opposite walls which are thinner than the other pair and produces a two-sided inflation in the direction perpendicular to the thinner walls. Originally, the thinner walls of the chambers are perpendicular to the long axis of the actuator body and inflate along with the long axis. These collinear inflations in chambers and the non-extensible base lead to an integral pure bending of the actuator. To explore the actuator&#39;s motion in 3-D space, the orientation of the chambers is tuned so that the thinner-side walls are no longer perpendicular to the long axis of the actuator (Figure 1A), which enables the inflation direction of each chamber to offset from the axis and become not collinear. All the parallel but not-collinear inflations change the motion of the actuator into a coupled bending and twisting motion in 3-D space18. This coupled motion enables the actuators more flexibility and dexterity and makes the actuators a suitable candidate for more practical applications, such as flexible manipulators, biologically inspired robots, and medical devices.
This protocol shows the fabrication method of this kind of soft pneumatic network actuators with oblique chambers. It includes preparing the silicone elastomer, fabricating the chamber and base parts, assembling the actuator, connecting the tubing, checking for leaks, and, if necessary, repairing the actuator. It can also be used to fabricate normal soft pneumatic network actuators and other soft actuators which can be produced with some simple modifications to the molding method. We provide detailed steps to fabricate a soft pneumatic actuator with 30&#176; oblique chambers. For different applications, actuators with different chamber angles can be fabricated according to the same protocol. Apart from that, the actuators can be combined to form a multi-actuator system for various demands.

<table border="0" cellpadding="0" cellspacing="0" style="width:796px;" width="794">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:207px;">Silicone elastomer</td>
			<td style="width:168px;">Wacker</td>
			<td style="width:135px;">ELASTOSIL M4601 A/B</td>
			<td style="width:287px;">Material of the actuators</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:207px;">Syringe&#160;</td>
			<td style="width:168px;">Shanghai Kindly Medical Instruments&#160;</td>
			<td style="width:135px;">10 ml</td>
			<td style="width:287px;">Used to inject silicone rubber into the hole of the mold for fabricating the connection end</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Precision scale</td>
			<td style="width:168px;">Shanghai Hochoice</td>
			<td style="width:135px;">UTP-313</td>
			<td style="width:287px;">Used to weigh the silicone rubber</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:207px;">Planetary centrifugal vacuum mixer</td>
			<td style="width:168px;">THINKY</td>
			<td style="width:135px;">ARE-310</td>
			<td style="width:287px;">Used to mix the silicone rubber and defoam after mixing process</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Release agent</td>
			<td style="width:168px;">Smooth-on</td>
			<td style="width:135px;">Release 200</td>
			<td style="width:287px;">Used for ease of demolding&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:207px;">Needle</td>
			<td style="width:168px;">Shanghai Kindly Medical Instruments&#160;</td>
			<td style="width:135px;"></td>
			<td style="width:287px;">Used for Piercing the bubbles form on the surface</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:207px;">Utility blade</td>
			<td style="width:168px;">M&#38;G Chenguang Stationery</td>
			<td style="width:135px;">ASS91325</td>
			<td style="width:287px;">Used for Scraping off excess silicone rubber along the upper surface of the mold&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:207px;">Vacuum oven</td>
			<td style="width:168px;">Ningbo SI Instrument</td>
			<td style="width:135px;">DZF-6050</td>
			<td style="width:287px;">Used to reduce the cure time of the silicone rubber</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:207px;">Male stud push in fit pneumatic fitting</td>
			<td style="width:168px;">Zhe Jiang BLCH Pneumatic Science &#38; Technology</td>
			<td style="width:135px;">PC4-01</td>
			<td style="width:287px;">Used to connect the tubing and the 3D-printed actuator tubing connector</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Tubing</td>
			<td style="width:168px;">SMC</td>
			<td style="width:135px;">TU0425</td>
			<td style="width:287px;">Used for actuating the actuators</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:207px;">Vacuum pump</td>
			<td style="width:168px;">Zhe Jiang BLCH Pneumatic Science &#38; Technology</td>
			<td style="width:135px;"></td>
			<td style="width:287px;">Used as the air source</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:207px;">Pressure valve</td>
			<td style="width:168px;">Zhe Jiang BLCH Pneumatic Science &#38; Technology</td>
			<td style="width:135px;">IR1000-01BG</td>
			<td style="width:287px;">Used for adjusting the input air pressure</td>
		</tr>
	</tbody>
</table>

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.

Single Actuator: 
To verify the fabrication method and demonstrate the function of the actuator, 30&#176;, 45&#176;, and 60&#176; actuators were fabricated and tested. For the experiment set-up, an air pump was employed to activate the valve. The valve was connected to the actuator to control the internal pressure. The single actuator was fixed at its connection end and placed vertically. While the actuator was being pressurized, two digital cameras were used to capt...

Watch this Scientific Journal Video about Fabrication of Soft Pneumatic Network Actuators with Oblique Chambers at JoVE.com

Fabrication of Soft Pneumatic Network Actuators with Oblique Chambers

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 ...

This method answers the key questions in the field of soft cell robotics by showing the fabrication method of soft pneumatic network actuators with oblique chambers that characterizes coupled bending and twisting motions. The main advantage of this technique is that it is fast, reliable, low-cost and suitable for the fabrication of soft pneumatic actuators with varied structures. Generally, individuals new to this method will struggle because the fabrication contains many steps, and one minor inappropriate operation can cause lethal failure of the actuators.The fabrication process requires molds. Design and 3D print a set of molds for the actuator with a 30 degree oblique chamber. Two parts will form the chamber mold, with one part having a hole to create a tubing connection.The third part will form a base. Next, place a mixing container on a scale. In separate syringes, have silicone elastomer component parts A and B.Use the syringes and scale to add the desired mass of each component to the mixing container.Now, move the mixing container to a Planetary Centrifugal mixer and mix well. After mixing, the silicone elastomer is ready for the protocol. Work with the mold pieces for the chamber.On each of the pieces, evenly spray mold release agent for silicone elastomer products. Orient the two pieces properly and bring them together to assemble the mold. Hold both ends of the mold with clips to prevent leakage.Get five milliliters of silicone elastomer with a syringe. Inject the elastomer slowly into the hole of the mold to fabricate the connection end. Then, fill the whole mold with the silicone elastomer.Use a low-flow rate and move the elastomer back and forth slowly. Once the mold is filled, use a needle to pierce any bubbles that form on the surface. Use a blade to scrape off excess elastomer on the upper surface of the mold.Now, place the mold in a 70 degrees Celsius oven until it is cured. After curing, inspect the mold. Use a syringe to inject silicone elastomer into bubbles and holes on the surface of the actuator.Scrape off any excess elastomer on the surface. Return the mold to the 70 degrees Celsius oven until it is cured. This is an example of a chamber produced by these steps after curing and demolding.Get the mold piece for the base. Spray mold release agent for the silicone elastomer evenly on its surface. Pour the silicone elastomer into the mold to fill it completely.Then, with a needle, pierce any bubbles that form on the surface. Scrape off any excess silicone elastomer along the upper surface with a blade. Place the mold in a 70 degree Celsius oven until the silicone elastomer is cured.This is an example of the base produced by these steps after curing and demolding. At this point, the actuator components are ready. Work with both a chamber and a base.Begin by pouring a one millimeter thick layer of silicone elastomer on one face of the base. Then, place the chamber part on the base. There will be a space between the two pieces.Use a syringe to inject silicone elastomer into the space. Place the actuator in the oven at 70 degrees Celsius until the elastomer is cured. After curing the actuator, tap the actuator tubing connector.It should accept the screw of a male stud push-in fit pneumatic fitting. With a needle, pierce the connection end of the actuator along the central line of the cylinder. Use a steel rod to increase the diameter of the hole to about two millimeters.Get the actuator tubing connector and screw it into the actuator. Once it is in place, push a section of tubing into the pneumatic fitting. The final step is to check for leaks.For this, use a container of water that can cover the actuator. Get the actuator and connect it to an air source. Place the entire actuator into the water and pressurize it.Observe whether bubbles are formed due to a leak. After the test, remove the actuator from the water. In this video, a 30 degree actuator starts under zero applied air pressure.As the pressure increases from zero kilopascals to 90 kilopascals, without interruption, the actuator both bends and twists. As the pressure is reduced, it returns to its original state. The bending angle for the actuator is defined as the angle between the body line in unactuated position and the body line in the actuated position.The twisting angle is the angle between the tip line in the unactuated position and the actuated position. This plot shows the bending angle as a function of pressure for actuators with oblique angles of 30, 45 and 60 degrees. Here is a similar plot for the twisting angle as a function of pressure.Note the difference in the vertical scales. While attempting this procedure, it is important to remember to pierce any bubbles that form on the top surface and scrape off excess elastomer on the upper surface of the mold before placing it into the oven. In this procedure, the silicone elastomer can be mixed manually and the elastomer can be cured at room temperature if the mixer and oven are not available.After its development, this method has paved the way for researchers in the fabrication of soft pneumatic actuators to explore oblique chambers capable of bending and twisting motion in 3D space. Don't forget that working with needles and blades can be extremely hazardous and attention should be paid;avoiding any hurt. In addition, nitrile gloves should always be worn when working with silicone elastomers.

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8.9K vistas.  Shanghai Jiao Tong University. This method answers the key questions in the field of soft cell robotics by showing the fabrication method of soft pneumatic network actuators with oblique chambers that characterizes coupled bending and twisting motions. The main advantage of this technique is that it is fast, reliable, low-cost and suitable for the fabrication of soft pneumatic actuators with varied structures. Generally, individuals new to this method will struggle because the fabrication contains many steps, and one minor...