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Medical Robotics: The Next Generation

Over the past few centuries, robotics has evolved in a variety of new, innovative ways. One of the earliest robots, The Mechanical Turk, was a chess-playing automaton controlled by a person hidden in its base. While this early mechanical device was touted as a "thinking machine," all of its moves were discretely controlled by a regular human.

Since that time, the science of robotics has changed significantly. New robotics systems like Intuitive Surgical's da Vinci system can perform minimally invasive operations with higher precision than a surgeon's hand. Many electronics and processors found in modern medical devices are built in foundries filled with robotic control systems. While many robotics technologies have improved in recent years, these machines have always been limited in the way that they move. However, that may change in the future.

Researchers at the National University of Singapore have developed a new type of artificial muscle designed from polymer-based fibers. The new technology could be used to improve the functional strength of robotics and other automated systems. In addition to medical robotics, the new technology could benefit medical device manufacturers too.

While robots can't move with the same freedom and fluidity as living animals, progress is moving forward at a rapid pace. For example, Big Dog is a robotic "mule" that can handle very well on complex terrains. However, Big Dog is limited by its movement system.

Big Dog utilizes a series of hydraulic actuators to move its legs. Like a backhoe, Big Dog uses a hydraulic pump to force fluid through a series of control valves. As fluid moves through these control valves, differences in pressure cause different pistons to expand and contract. While this technology has improved significantly in recent years, hydraulic actuators have several significant limitations. While modern systems are high-precision, many hydraulic actuators suffered from poor movement. In addition, hydraulic systems have strength cutoffs that can limit their applications. The new artificial muscle is designed to mimic human muscles instead of hydraulic actuators. By mimicking human muscles, the new "organic-inspired" actuators can respond quickly to an electrical impulse.

"Robots move in a jerky manner because of this mechanism. Now, imagine artificial muscles which are pliable, extendable and react in a fraction of a second like those of a human. Robots equipped with such muscles will be able to function in a more human-like manner - and outperform humans in strength," noted Dr. Adrian Koh, lead engineer.

To develop this technology, researchers created a polymer that could be stretched up to 10 times its original length. This correlates with a strain displacement of 1,000%. Based on this, the new artificial muscle could theoretically lift an object up to 500 times its weight.

As of now, researchers were able to create a robotic polymer muscle that can bear 80 times its own weight. The polymer muscle can also extend to five times its original length.

One significant benefit of the new polymer is that it can both store and generate energy. As the artificial muscle expands and contracts, it converts electric energy into mechanical energy. Due to its mechanical properties, it can hold a significant amount of energy in a small area. According to researchers, a 10 kg system built from this soft material could produce the same amount of energy as a one-ton power turbine.

Based on this, researchers believe that systems equipped with these artificial polymer muscles could recharge themselves after exerting a force. Like a hybrid vehicle, robots equipped with this new technology could "recycle" energy during movement.

As of now, a robot utilizing this technology has not been built. While researchers have filed a patent for the artificial polymer muscles, a real robot is still a few years away. Dr. Koh hopes to build a robotic arm with the new muscles in the next five years. If successful, the robotic arm could weigh half as much as a traditional human arm. However, it will be just as strong as a regular organic arm.

For prosthetics, the new technology could be revolutionary. Instead of bulking up artificial limbs with massive motors and actuators, prosthetics manufacturers could create lightweight, high-dexterity limbs. However, commercial applications are still years away.

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