Soft robotics is a subfield of robotics that builds mechanical systems out of flexible, compliant materials. Often inspired by biological structures found in nature, soft robots can possess a limitless number of joints, and are typically made out of elastic, deformable materials like silicone rubber or gels that can stretch, bend, squeeze or twist without losing shape. This technology is used today in industries like manufacturing, healthcare and ocean exploration.
Soft Robotics Definition
Soft Robotics is a subfield of robotics that builds machines out of flexible, deformable materials designed to mimic biological movements.
What Is Soft Robotics?
Soft robotics focuses on making robots from pliable materials that allow them to bend and return to their original shapes. These robots are often biocompatible and can adapt to complex environments — including human interaction — with minimal damage or risk. They’re actuated in unique ways — from air or fluid pressurization to electrical signals and heat stimuli — by sources typically found outside of their body. These actuation systems control how the soft bot moves, determining its range of motion and how it interacts with its surroundings.
It’s Not New — But Newly Relevant
Even though soft robotics is largely considered an emerging technology, “the concept of using rubbery materials, balloons and other soft structures in robotics has actually been around for over half a century,” according to Carmel Majidi, professor of mechanical engineering at Carnegie Mellon University. It’s only gained renewed interest lately due to “an increasing demand for robots in applications outside of factory production and industrial automation,” Majidi added.
How Are Soft Robots Different From Traditional Robots?
Unlike traditional robots — which are assembled out of hard, metallic components and designed to perform precise, repetitive tasks with speed and strength — soft robots are highly adaptable to dynamic scenarios and can interact safely with humans or delicate objects. And instead of rigid motors, soft robots use alternative actuation methods, like inflatable chambers, heat or magnets, to create movement.
Their gentle touch makes soft robots essential for human-centric applications. Aside from joining human workers as cobots in warehouses and on factory assembly lines, their dexterity enables delicate exploring “inside and around the human body” for medical use, said Jacqueline Libby, assistant professor of mechanical engineering at Stevens Institute of Technology, where she also directs the Robotics Systems for Health Lab. In healthcare, soft robots are used to build prosthetic limbs, assist in surgery and embedded into soft suit exoskeletons that can restore mobility for stroke and ALS patients, for example.
Soft robots are somewhat paradoxical, Libby told Built In. “Because on one hand, the fact that they can have an infinite number of joints makes them some of the most complex robots out there,” she continued. “But on the other hand, they’re also very simple.” A rigid robot, for instance, has a motor at every joint. But with a soft robot, you might just have one source of air that controls a bunch of joints all at once. This way, their intelligence is largely encoded into the materials that are used to make up its physical body rather than software or artificially intelligent algorithms.
How Is Soft Robotics Used?
In comparison to hard robots, soft robots “are more closely matched to the properties and capabilities of soft human tissue or soft biological organisms, Majidi said, “which could have a transformative impact in a variety of fields.”
Healthcare
Because soft robots are flexible and biocompatible, they can interact with the human body in a number of ways. They can navigate through the human body with minimal tissue damage when conducting minimally invasive surgeries and, in pill form, administer directed drug delivery. As bionic prosthetics and physical therapy exosuits, they provide gentle, adaptive support for patients with mobility impairments or recovering from injuries.
Agriculture
Soft robotics, particularly soft grippers, allow for delicate handling and harvesting of fruits and vegetables without causing damage. Highly adaptable, these machines automate in-field tasks like weeding, planting, picking and crop monitoring.
Manufacturing
In manufacturing, soft robots offer a gentler touch when it comes to moving products in warehouses and on factory assembly lines. They can handle fragile and irregularly shaped objects — reducing the risk of damage compared to hard robots — and perform various tasks like assembly, packaging and quality control that contribute to improved efficiency and safety in automated production lines.
Ocean and Space Exploration
Soft robots can withstand extreme pressure and temperature variations in harsh conditions. Their soft, deformable bodies enable them to navigate challenging terrains, such as underwater crevices or the surface of distant planets, while safely interacting with delicate ecosystems or equipment.
Search and Rescue
The flexible, adaptable bodies of soft robots allow them to navigate through tight spaces and tough terrain typically inaccessible to rigid robots. Because of this, they can safely interact under harsh conditions and even provide assistance to trapped individuals by squeezing through confined areas during emergency rescues.
Soft Robotics Examples
K-FLEX, a Flexible Surgical Robot
A research team at the Korea Advanced Institute of Science and Technology has developed a tiny soft robot designed to perform scar-free endoscopic surgery. Using a pair of arms, both 3.7 millimeters in diameter, that extend out from a multi-jointed endoscope, K-FLEX demonstrates precise control of live tissue.
Wyss Institute’s Soft Exosuits
By pulling cords attached to a user’s shoe insole, an exosuit built by researchers at the Wyss Institute helps stroke victims regain use of their legs. Taken from tech concepts designed for military applications, the lightweight attachment provides joint assistance and corrects abnormal gait patterns to help maintain balance, with patients exhibiting immediate improvement in their walking performance.
MIT’s Bionic Heart
MIT engineers have 3D printed a robotic replica of a heart’s right ventricle that can be controlled to mimic a patient’s blood-pumping ability. Made out of real heart tissue and synthetic, balloon-like artificial muscles, the soft bot acts as a research tool that can help doctors study cardiovascular diseases and determine the best course of treatment for heart-disease patients and transplant candidates.
Soft Robotics’ Soft Grippers
Cambridge-based company Soft Robotics developed soft end-effectors that can pick up objects of various shapes, weights and sizes. With softer materials, robots can successfully perform tasks without the need to know the exact mass or location of its target — a benefit to farming when it comes to accommodating the varying dimensions of freshly grown produce.
Festo’s Robotic Arms
German robotics company Festo has developed a modular lightweight bionic arm designed for human-robot collaboration. Operators can swap out the gripper style for several different variations of gentle and secure object manipulation, ranging from its octopus-arm TentacleGripper to its adaptive shape gripper that’s engineered to mimic a chameleon tongue.
China’s Deep-Sea Soft Bot
Inspired by a deep-sea hadal snailfish, a team of engineers in China developed a battery-powered soft robot that can reach the Mariana Trench — the deepest point in the ocean. The 22-centimeter machine can withstand more than a thousand times the pressure experienced above sea level, and can dive up to 10,900 meters below the surface.
NASA-Sponsored Burrowing Space Robot
NASA is teaming with researchers at the University of California and the Georgia Institute of Technology to further develop their burrowing soft robot that can navigate sandy terrain. Moving like a plant tendril, the device extends its tip to push or blow air at surrounding material to move it out of the way. One day, the team hopes to send it to explore the surface of the moon and other celestial bodies, like Enceladus, a Jupiter moon.
Stanford’s Vinebot
This pneumatic-powered prototype from Stanford engineers is a snake-like soft robot that starts out as a flexible plastic tube, then expands as it’s filled with compressed air, growing and contorting itself like a vine as it moves through challenging environments. Built with a camera and sensor-enhanced steering, it’s currently in the proof-of-concept stage, where the soft bot has traversed obstacles including fly paper, sticky glue and nails without faltering and lifted a 100-kilo crate, showcasing its potential for heavy-duty tasks like freeing disaster victims from collapsed buildings.
North Carolina State University’s LEAP Bot
Researchers at North Carolina University have built one of the fastest soft bots to date, the LEAP robot. Built with a spring-powered, bi-stable spine, this galloping machine mimics the spine flexion and extension exhibited by running cheetahs. At just seven centimeters long and 45 grams in weight, it can also grab and lift relatively heavy objects.
Advantages of Soft Robotics
The benefits of soft robotics include increased safety, adaptability and a wider range of use cases. Some experts expect them “to replace rigid robots in a range of applications as research advances and achieves greater maturity,” said Inderjeet Singh, a research scientist of biomedical technologies at the University of Texas at Arlington and member of the IEEE Robotics and Automation Society.
Safety
Soft robots, made from flexible materials, reduce the risk of injury during physical contact, making them suitable for collaborative tasks and direct human interaction. This safety feature is particularly important in applications such as healthcare and wearable technology, where gentle handling is crucial.
Adaptability
Soft robots can easily deform and navigate through tight, uneven or unpredictable spaces. This versatility makes soft robots ideal for applications such as search and rescue, where they can maneuver through debris, or for delicate tasks like handling fragile objects.
Structural Flexibility and Dexterity
Soft robots can bend, stretch and twist in ways that rigid robots simply can’t. With soft grippers, flexible joints and pneumatic systems, these machines recreate biological motions in order to handle objects of various shapes, weights and sizes while performing complex tasks that require a high degree of control.
Biocompatibility
Soft materials used in these robots are often compatible with living tissue, making them well-suited for medical applications like surgery, rehabilitation and prosthetics. This factor ensures that machines do not cause adverse reactions or harm when in contact with the human body, enabling more seamless integration into medical procedures and treatments.
Lightweight
Without heavy motors at every joint, soft robots can move with greater agility and require less energy for operation than their rigid counterparts. Made from lightweight materials like silicon rubber and gel, their low weight reduces the strain on structures or surfaces they interact with, allowing for delicate handling of objects and ease of deployment in a variety of scenarios.
Disadvantages of Soft Robotics
Still, there’s room for improvement for these soft-build newcomers — they are limited in strength, may lack durability and their movements are difficult to precisely predict.
Limited Strength and Load-Bearing Capacity
Soft robots often cannot handle heavy loads or exert significant force compared to hard robots. As you can imagine, flexible materials generally cannot support heavy objects or exert the same amount of force of an industrial-grade robotic arm, making them less suitable for tasks that require substantial power, iteration or endurance. This limitation restricts their use in applications that involve lifting, carrying or applying pressure to large or heavy items.
Low Precision
Although flexible materials and deformable structures come with a great number of advantages, they make it challenging to achieve exact movements and positions, which can lead to inaccuracies in tasks requiring fine control. This limitation directly affects their performance in applications where exactness is crucial.
“Despite the numerous advantages of soft robotics — such as flexibility and adaptability — hard robots remain superior in terms of precision and accuracy,” Singh said. As a result, researchers are currently refining algorithms, improving sensor technology and creating advanced control systems that can deliver controlled movements using soft materials.
“The goal is to combine the benefits of soft robotics with the accuracy typically associated with rigid robots,” he added.
Complex Sensing
Because the deformable body of soft robots is less precise and slightly more unpredictable than their rigid counterparts, they require extensive sensing systems and advanced algorithms in order to effectively manage their movement. This level of nuance can result in inconsistent or unreliable performance from the soft bot, particularly in dynamic environments.
Low Durability and Wear
Soft materials are more prone to degradation or damage over time — directly affecting the robot's performance. Soft robots have a shorter lifespan than hard robots, and suffer greater wear and tear. This vulnerability can lead to reduced performance as well as increased maintenance needs, especially with high repetitive use or when operating in harsh conditions.
Difficult to Manufacture
Since soft robots are newer to the scene, it’s a given that they’re going to be more difficult to produce than hard robots, which benefit from already having manufacturing infrastructure in place. Additionally, soft robots are made using intricate fabrication techniques that are difficult to scale, as they require specialized materials and customized molds.
Frequently Asked Questions
What are soft robotics?
Soft robotics focuses on building machines out of flexible, deformable materials that are designed to mimic biological movements.
What is the difference between hard robotics and soft robotics?
Hard robots are built out of rigid, typically metal or plastic components and are designed for strength and precision, whereas soft robots are made with flexible, elastic materials that allow for more adaptable, gentle movements within dynamic scenarios — namely human interaction.
How will soft robotics be used in the future?
Based on current trends, it’s likely that soft robotics will become increasingly integrated into medical devices, the assembly lines of manufacturing facilities and agritech tools for crop harvesting.
