There are many applications in today’s world for the field of soft robotics, especially when combining the technology with 3D printing, from creating better prosthetics and making it safer to work on the factory floor to allowing people to experience tactile feedback in a virtual environment. 3D printing technology can even be used to build small, flexible robots capable of navigating through confined spaces, like the human body. This kind of important work is what led researchers at Jeju National University in South Korea, already familiar with soft robotics, to conduct a review of the technology.
The research team took an in-depth look at all of the latest developments and research in 3D printing soft robots, and published their findings in a paper, titled “3D printing for soft robotics – a review,” in the journal Science and Technology of Advanced Materials (STAM).
The abstract reads, “Soft robots have received an increasing attention due to their advantages of high flexibility and safety for human operators but the fabrication is a challenge. Recently, 3D printing has been used as a key technology to fabricate soft robots because of high quality and printing multiple materials at the same time. Functional soft materials are particularly well suited for soft robotics due to a wide range of stimulants and sensitive demonstration of large deformations, high motion complexities and varied multi-functionalities. This review comprises a detailed survey of 3D printing in soft robotics. The development of key 3D printing technologies and new materials along with composites for soft robotic applications is investigated. A brief summary of 3D-printed soft devices suitable for medical to industrial applications is also included. The growing research on both 3D printing and soft robotics needs a summary of the major reported studies and the authors believe that this review article serves the purpose.”
Traditional hard robots are rigid, and require things like fluidics and pneumatics. Soft robots, however, are fabricated using flexible, compliant materials like polymers, fluids, and gels, in order to give them the ability to mimic functions in living organisms. While conventional molding and casting processes were the preferred method of manufacturing in the past, this has been trending more towards 3D printing technology over the last few years.
While many reviews exist about various 3D printing technologies and soft, 3D printable materials, according to the paper, a review has never been completed that focuses on 3D printing in soft robotics until now.
“In an effort not to overwhelm the reader, the scope of the paper is limited in several ways. The focus is on 3D printing fabrication technologies with soft structure examples, materials that can be 3D printed for soft robotic applications and soft medical devices that are 3D printed,” the paper reads.
There are many available types of 3D printing technology, which use different approaches of layering material to make an object. For example, one research team used SLS printing to fabricate a multi-finger soft robotic hand, out of powdered metal material, that’s able to grip, lift, spin, and position objects.
Other 3D printable materials for soft robots include shape memory polymers, dielectric elastomers that change shape and size when stimulated by an electric field, and hydrogels affected by different stimuli, such as acidity, electricity, heat, light, and magnetism.
3D printing can be used to fabricate personalized, medical soft robotics for use both inside the body and out. 3D printed soft micro-biobots can travel through a person’s gut or blood vessels to monitor diseases, and a 3D printed soft silicone pump could also be used as an artificial heart. Soft robots can monitor a person’s vital signs, and even replace animals in drug testing by being used in organ-on-a-chip devices.
Overall, the study shows that 3D printing technology can definitely be used to build robots with porous internal structures and complex external shapes.
According to the paper, “Demand for 3D printing technologies such as SLS and 3DP will increase in the future due to their capability to make custom soft robots that can be tailored for application-specific and defect-specific needs.”
But there are many challenges to tackle in order to improve use in a clinical setting, and 3D printing is not quite fast enough for mass production yet. Sometimes materials shrink during solidification, and there are issues that need to be overcome in terms of 3D printing robots with several materials that can adhere to each other easily.
The paper concludes, “Lastly, commercial success depends on new innovation in soft lithography, 3D printing and other rapid prototyping technologies to mass produce soft structures and robots that are inexpensive and satisfy market demand.”
Co-authors of the study include Jahan Zeb Gul, Memoon Sajid, Muhammad Muqeet Rehman, Ghayas Uddin Siddiqui, Imran Shah, Kyung-Hwan Kim, Jae-Wook Lee, and Kyung Hyun Choi.[Source: Benzinga / Images: Jeju National University]