Since the first breakthrough in robotic technology, robots have been built to run on motors. Today, robots are still primarily motor-driven. While being an effective system for navigation and control, motors are often bulky and complex, making robots inflexible to operate across various mediums. A recently published study aims to make robots completely motorless, featuring an actuating material that reacts to visible light, electricity, and other stimuli.
This new material, nickel hydroxide-oxyhydroxide, can produce force equivalent to 3000 times more than its own weight through deformation. It can be actuated by visible light at a relatively low intensity, producing high levels of stress and speed similar to the skeletal muscle functions in mammals.
Mechanical engineers from the University of Hong Kong (HKU) demonstrated the capabilities of the material through a mini-arm composed of two-hinge actuators. When exposed to light, the arm immediately lifts the object, which is actually 50 times the weight of the arm. The material was electroplated on selected areas of the substrate to serve as a hinge actuator, lifting the objects by bending or curling in the presence of light.
Mini-Arm Actuator Demonstration. (Courtesy of the Department of Mechanical Engineering, University of Hong Kong.)
According to the study, nickel hydroxide-oxyhydroxide can also be actuated by electricity, showing positive results for potential integration with current robotic technology. Additionally, it has also shown to be responsive to changes in heat and humidity. This could mean the potential application of the material in autonomous machines that harness energy from environmental stimuli.
The introduction of nickel hydroxide-oxyhydroxide ushers in a new field of research in stimuli-induced actuating behavior for hydroxide-oxyhydroxides. The team of engineers behind the material expects that this can initiate research towards the production of motorless robots and biomimetic devices such as artificial muscles. Artificial muscles and human assist devices require wireless navigation for ease of use in practical applications, such as invasive surgical and diagnostic tools used in the medical field.
The cost to innovate and produce alternative actuators for biomimetics and artificial muscles remain high, preventing successful entry into the field. However, since the major component of the material is nickel, material costs are low compared to other actuators. According to the engineers from HKU, the fabrication of such an actuator takes only three hours. This means the material can easily scale in a high-intensive manufacturing environment.
The engineers predict that actuating materials using nickel hydroxide-oxyhydroxide can be applied to various technological devices in the future, including rescue robots or mini-robots.
Walking Bot Actuator Demonstration. (Courtesy of the Department of Mechanical Engineering, University of Hong Kong.)
The team was led by Professor Alfonso Ngan Hing-wan, Chair Professor in Materials Science and Engineering, and Kingboard Professor in Materials Engineering, Faculty of Engineering.
Their paper, “Light-stimulated actuators based on nickel hydroxide-oxyhydroxide" was published in Science Robotics on May 30, 2018.
For more breakthrough innovations in robotic technology, check out how this study on Soft Actuators Signal a Step Toward Artificial Muscles.