Four core materials supporting 3D printing soft robots

As an emerging field in the research field, soft robotics technology has been favored by 3D Printing manufacturers since its emergence. Today, 3D printing has become a fully integrated manufacturing process in the field of soft robotics. However, 3D printing still has some shortcomings when facing the manufacturing of all-printed soft robots. One of them is the lack of high-performance materials required for printing soft robots.
Ela Sachyani Keneth of the Hebrew University of Israel and others published a review article titled “3D printing materials for soft robots” on Advanced Materials.
The article carefully discusses high-performance materials for 3D printing, and summarizes the materials required for 3D printing soft robots, including high-performance flexible and stretchable materials, hydrogels, self-healing materials, and shape memory polymer.

High-performance flexible and stretchable materials

The 3D printing materials that have both of these two characteristics mainly include PVC and TPE. PVC material mostly refers to polyvinyl chloride, which is a kind of hydrocarbon containing chlorine; TPE material, also known as thermoplastic elastomer, is a hydrocarbon and has both Both plastic and rubber characteristics.
PVC material used to be the world’s largest production of general-purpose plastics, used in many fields, such as daily necessities, floor leather, artificial leather, pipes, wires and cables, packaging films, and bottles. As a new generation of synthetic rubber, TPE materials are not as widely used as PVC. However, TPE materials have begun to replace some traditional synthetic rubbers, and their application areas are expanding.
As a new-generation material, TPE is superior to PVC materials in terms of mechanical properties, hardness, specific gravity, and environmental protection. Currently on the market, the TPE materials of Teknor Apex Company are very popular among users. The main material models are: Medalist MD-84348, Medalist MD-8431, Medalist MD-84368.

Hydrogels

Hydrogel, sometimes called colloidal gel, is a kind of extremely hydrophilic three-dimensional network structure gel, which can swell rapidly in water and maintain a large volume of water without dissolving in the swollen state.
Similar to biological soft tissue, hydrogel has a unique microenvironment (high water content and permeability) and self-adaptive characteristics. It is not only suitable for 3D printing soft robots, but also used in moisture regulators, wound dressings, food preservation agents and Flexible electronic devices and many other fields show great application potential. However, the mechanical properties of traditional hydrogels are general, which limits their practical applications.
Fortunately, on November 30, 2020, Wang Xiaolong, a researcher at the State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, and his team realized the 3D printing of ultra-high-strength hydrogels by constructing a dual physical cross-linking network. A research result has greatly expanded the practical application of hydrogels.

With the continuous development of technology, hydrogels made of different materials have gradually appeared, showing many new characteristics, such as self-healing, multiple stimulus responses, and super wettability.