Fabrication of Soft Pneumatic Network Actuators with Oblique Chambers

Summary

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.

Abstract

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.

Introduction

Soft pneumatic actuators (SPAs) are soft devices that can be actuated by the simple input of air pressure^1,2. 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 applications^8,

Protocol

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

1. Weigh 5 g of silicone elastomer part B and 45 g of part A [9:1 (A:B) parts by weight] in the same mixing container (Figure 2A). Use a syringe to make sure the proportions of each part are accurate.

Results

Single Actuator:
To verify the fabrication method and demonstrate the function of the actuator, 30°, 45°, and 60° 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.......

Discussion

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.......

Materials

Name	Company	Catalog Number	Comments
Silicone elastomer	Wacker	ELASTOSIL M4601 A/B	Material of the actuators
Syringe	Shanghai Kindly Medical Instruments	10 ml	Used to inject silicone rubber into the hole of the mold for fabricating the connection end
Precision scale	Shanghai Hochoice	UTP-313	Used to weigh the silicone rubber
Planetary centrifugal vacuum mixer	THINKY	ARE-310	Used to mix the silicone rubber and defoam after mixing process
Release agent	Smooth-on	Release 200	Used for ease of demolding
Needle	Shanghai Kindly Medical Instruments		Used for Piercing the bubbles form on the surface
Utility blade	M&G Chenguang Stationery	ASS91325	Used for Scraping off excess silicone rubber along the upper surface of the mold
Vacuum oven	Ningbo SI Instrument	DZF-6050	Used to reduce the cure time of the silicone rubber
Male stud push in fit pneumatic fitting	Zhe Jiang BLCH Pneumatic Science & Technology	PC4-01	Used to connect the tubing and the 3D-printed actuator tubing connector
Tubing	SMC	TU0425	Used for actuating the actuators
Vacuum pump	Zhe Jiang BLCH Pneumatic Science & Technology		Used as the air source
Pressure valve	Zhe Jiang BLCH Pneumatic Science & Technology	IR1000-01BG	Used for adjusting the input air pressure