Biomedical engineers have developed a new soft robotic system that works without electricity or motors, allowing for more precise surgeries at lower cost.
The prototype system, designed by the UNSW Medical Robotics Lab led by Dr Thanh Nho Do, uses hydraulics to manoeuvre 'artificial muscles' that enable a flexible robotic arm to move in all directions.
One potential major application is controlling microcatheters being used in complex endovascular procedures.
In addition, the new system – known as Soft Fibrous Syringe Architecture (SFSA) and described in a paper in Advanced Science – has built-in sensing capabilities that can detect forces and surface textures.
That could allow medical professionals to more accurately detect and operate on abnormal or excessive cells in the body, such as tumours.
"Unlike traditional methods that use complicated parts like electric motors, microcontrollers, valves, and rigid pumps, SFSA uses a simple mechanical system that doesn't need electricity or motors," says Dr Do, a Scientia Senior Lecturer at UNSW's Graduate School of Biomedical Engineering and Tyree Foundation Institute of Health Engineering (IHealthE), who worked in collaboration with other researchers from UNSW including Chi Cong Nguyen, Scientia Professor Nigel Lovell, and Dr Hoang-Phuong Phan.
"The SFSA solves many problems in flexible robotic systems by removing the need for complex controllers, electronics, and large power sources, as well as cutting out extra sensors.
"This makes the flexible robot easier to build, fix, and maintain, making it more user-friendly and less likely to fail.
"In terms of soft robotic microcatheters, the SFSA also allows the device to be smaller and lighter, which makes it easier and more precise to operate. That is especially important in medical situations like endoscopic surgery or in the urgent treatment of strokes where blood clots in the brain need to be removed quickly."
Artificial muscles
The new SFSA system consists of connected soft artificial muscles, called 'master' and 'slave'. Each muscle is made up of a rubber tube on the inside, which is reinforced with a spiral coil of strong fibres on the outside.
The master muscle works like a regular medical syringe but without a sliding plunger, like a 'soft syringe'. The slave muscle acts as a flexible soft actuator – or more simply the element that controls the movement.
When the master muscle is stretched, it changes the hydraulic pressure in the SFSA system, making the slave muscle shorten and produce movements.
This mechanical design reduces production costs since it needs fewer expensive electronic parts. That also increases its reliability and improves safety, since there is reduced risk of electrical problems.
It can be used more quickly and easily in remote areas, with applications even possible in space wherever robotic arms would potentially be used.
The researchers say the SFSA's inherent properties make it well-suited for the future development of flexible surgical robotic systems – most notably the built-in sensing.
"That capability enables this system to perform dedicated tasks such as stiffness detection of neoplasms, which are abnormal growths inside the body, as well as surface-mapping and texture detection," says Chi Cong Nguyen, a PhD candidate working with Dr Do.
"Our soft robot can execute critical procedures such as surgical treatment and delivery of biomaterial to precise locations."
Reducing tremors
In addition, the SFSA can be easily 'tuned' to scale down the motion being inputted by the controller.
The result is that, for example, any small tremors from the hand of a surgeon would effectively be eliminated, thereby enhancing the accuracy of procedures and making SFSA particularly well-suited for microsurgery where high precision is vital.
"This new technology uses off-the-shelf materials, which greatly reduces the costs compared to traditional electric control systems, but also makes SFSA simpler, more reliable, smaller, and easier to operate - making it perfect for many medical uses," says Dr Phan.
"By eliminating the need for electricity, DC motors, and controllers, this new technology provides a low-cost solution that is naturally more reliable. The robot's ability to work without needing a power source makes it even better for places where power is limited or unavailable."
Scientia Prof. Lovell, Head of the Graduate School of Biomedical Engineering and Director of the Tyree IHealthE, added: "Its flexible design helps it move through tight spaces more easily than traditional systems, and the reduction in electronic parts lowers both costs and maintenance needs.
"This approach offers a strong, efficient, and affordable alternative, especially where traditional technologies don't work as well."
Dr Do has plans to combine this new SFSA system with a soft wearable glove, rather than just a traditional joystick, which would provide real-time haptic feedback to the user.
The researchers acknowledge that more work needs to be done before the new system can be used in real-world medical settings.
They are aiming to further improve the materials used and refine the design for better performance and to ensure the technology is reliable and durable in different environments.
Suitable testing would also need to be carried out and regulatory approvals obtained before implementation in surgical procedures – following rigorous training for users.
