Man-machine symbiosis: Evolution of prosthetics from masking injuries to enhancing abilities

Prostheses were once simple body parts made of wood, plastic, or metal alloys, mainly used to cover any disfigurements. Now, with the efforts of countless scientists, they have become functional extensions of the human body. 

For decades, prosthetic limbs were rigid devices that offered some level of functionality but very limited control or adaptability. Users experienced restricted control over movement. However, advancements in robotics and bioengineering have led to modern prosthetics that go beyond covering disfigurements and help restore or even enhance motor, sensory, and neural capabilities.

By integrating advanced sensors and artificial intelligence, these devices now mimic natural limb movements, enabling users to control their medical prosthetics as if they were extensions of their own bodies. These prostheses include sensors, motors, and actuators, allowing for more intricate and precise control.

A BioRobotics Institute research team, led by Prof Christian Cipriani at Sant'Anna School of Advanced Studies in Pisa, has developed the first-ever magnetically controlled prosthetic hand that allows users to use it like their own hand with just their thoughts as part of the MYKI project.

This innovation allows an amputee to perform natural movements without relying on electrical connections and wires. Instead, the prosthesis uses myokinetic control. For this, six magnets are implanted in six key places in the hand. When the test patient, 34-year-old Daniel, thought of moving his lost hand, the implanted magnets would respond to the contractions, which, in turn, created signals that dictated the action to the robotic limb. 

Besides giving users a sense of control, these advanced prosthetics offer sensory feelings that were previously impossible. One such key technology is MiniTouch, which can be integrated into different prosthetics to give the amputee the sensation of warmth and coolness.

 A research team from the same Sant'Anna School of Advanced Studies and the Swiss Federal Institute of Technology Lausanne has developed this system that allows users to perceive temperature, which has proven to be 100% accurate even when Fabrizio, a 57-year-old test patient, was blindfolded. 

Bioelectronic interfaces have also prompted a significant leap in modern medical prostheses. This approach has enabled amputees to connect with their prosthetic device on a deeper level through the person's own nervous system. This type of interface basically establishes a bidirectional communication between the user's peripheral nerves and his prosthesis, creating a man-machine symbiosis by allowing sensory feedback and natural proprioception.

While traditional prostheses depend on sensors and mechanical controllers for any movement, this new interface, through a surgical process called the Agonist-antagonist Myoneural Interface or AMI, reconnects muscles in the user's remaining part of the limb and restores his proprioceptive feedback. This ability to sense the limb's position has resulted in better obstacle navigation and walking speed in all seven patients who underwent the AMI procedure. 

These AMI prosthetics deliver seamless, lifelike movements—allowing users to naturally adapt their gait, navigate stairs, and tackle varied terrains as neural signals guide each step. This small increase in neural feedback led to lifelike-normal walking abilities, marking a substantial advancement in prosthetic control and comfort.

MIT's biophysicist Hugh Herr and his team integrated the bionic leg with such a neural interface to give users a sense of self, which offers both emotional and physical benefits. Patients with these neural interfaces connecting their bodies with machines have reported a 41% increase in walking speed and the ability to handle obstacles, stairs, and slopes.

Noninvasive options are also improving. California-based Atom Limbs has developed an artificial intelligence and machine learning powered bionic arm that offers human motion and haptic feedback. But unlike other prostheses, where you have to undergo surgery to interpret neuroelectric signals, this company is promoting a noninvasive way to steer the prosthetic limb using sports vests and bands wired with different sensors.

Armless since birth, Paul Carter, a reporter at BBC, tested this new system and boasted his ability to control virtual movements, creating the sensation of manipulating a missing limb; something he has never experienced.

This sort of groundbreaking leap in prosthetic technology came from the advent of mind-controlled devices, which leverages brain-computer interface (BCI) technology to interpret neural signals directly from the user's brain, allowing for a more intuitive, seamless control of artificial limbs. Pioneers like Elon Musk's Neuralink and research teams at leading universities are pushing the boundaries of this innovation, enhancing the responsiveness and adaptability of these prosthetics. 

As advancements in prosthetic technology continue at an unprecedented pace, the line between man and machine grows ever thinner. What was once a simple aid for physical mobility is now a testament to human ingenuity, capable of restoring a profound sense of self to its users. 

This symbiosis promises a future where the integration of humans and machines feels as natural as flesh and bone, bringing hope and empowerment to millions worldwide.