A new plastic material, inspired by the clotting action of human blood, has been created by engineers at the University of Illinois.
The plastic contains a network of "capillaries" that mimic the action of blood vessels in the human body, delivering chemicals to "heal" and repair damaged plastic "tissue."
The designers of the new polymer envisage that it could be utilised to restore cracked phone screens or electronic chips in laptops, but the possibilities could be applied to an unlimited array of plastic items. Water pipes, sports equipment, homewares and appliances, car parts, even satellites could repair themselves in space.
In fact, this technology is not new, being first engineered in 2001 when Professor Scott White and his team at Illinois University managed to infuse a polymer with microscopic capsules containing a liquid healing agent. They discovered that when the material cracked, chemicals were released to bridge the gaps. Since then, concrete, water-resistant coatings, and even electrical circuits have all been engineered with self-healing properties, but only small repairs have been possible.
"Although self-healing of microscopic defects has been demonstrated, the re-growth of material lost through catastrophic damage requires a regenerative-like approach," said Prof White.
The latest breakthrough has therefore used a method inspired by the human vascular system, where a network of channels convey restorative chemicals to the damage site. The chemicals arrive via two separate streams which combine to seal holes in a two-stage reaction, firstly forming a gel scaffold across the gap, then applying a gel that slowly hardens into a solid structure.The process takes much less time than biological tissue repair, however, with researchers reporting that repairs could take a matter of hours not days:
"We filled regions exceeding 35mm within 20 minutes, and restored mechanical function within three hours,” described Prof Scott White from the University of Illinois.
The latest polymer can now repair holes up to 3cm wide, 100 times bigger than before, and this opens up even greater possibilities for its utilisation.
Over the past decade there has been a growing interest in "self-healing" polymers with various different versions being created, including plastics that can join their cut edges together by photosensitivity to light, in response to heat, or when simply held together. In 2008, researchers at ESPCI ParisTech designed a rubber compound that could recover its mechanical properties after being broken and healed repeatedly, just like skin.
The obvious comparisons to physiological systems have led researchers to consider the use of such polymers in medical applications. A study back in 2012 conducted by scientists in California focused on designing a flexible, electrically conductive, self-healing polymer."Epidermal electronics" as they are known involve the production of circuits thin and flexible enough to be attached to skin and can be incorporated into heart rate monitors or to add touch sensitivity to prosthetic limbs.
The latest developments in this field have coincided with the launch of a new prosthetic limb that responds to "mind control." After almost eight years of tests at DARPA, the US Defense Department's advanced research agency, the Food and Drug Administration (FDA) have granted approval to one of the projects: a mind-controlled prosthetic limb called the DEKA Arm, known affectionately as "Luke" after the Star Wars hero who receives a perfect arm replacement in the film Empire Strikes Back.
Though similar projects are being researched by scientists and engineers globally, this is the first such prosthetic to get FDA approval. The prosthetic device, which is made by a company founded by Segway inventor Dean Kamen, is the approximate size and weight of an adult arm, and is controlled by electromyogram electrodes placed on the remaining portion of the human arm. The sensors respond to electric signals from muscle movements in the upper arm, which are processed by a computer in the robotic arm to determine the type of movement required.
Clinical trials have yielded excellent results, with the new arms granting a range of movements to amputees that were previously impossible with other prostheses.
For those unfortunate enough to have lost a limb, the potential of these new technologies must seem like a dream come true. If these new artificial limbs are subsequently combined with self-healing plastic "skin," they would almost be comparable to their biological predecessors. Eventually, the human race may have the capability to recreate and replace all faulty body parts with fully-functioning alternatives that meld harmoniously into our original biological forms until we will become more machine than man.
The most elegant use for the new technologies would be to replace limbs or body parts lost through disease or injury, or destroyed tissue, and one wonders if the same technology could somehow be combined with human tissue to re-grow missing limbs.
But is the dawn of a new age, the age of the Cyborg?
Technically, even those fitted with pacemakers are could be considered to be cyborgs, which is short for short for "cybernetic organism", a being with both organic and bio-mechatronic parts.
Traditionally, however, the name cyborgs - a term coined by Manfred E. Clynes and Nathan S. Kline in 1960 to describe their conception of an enhanced human being who could survive in extraterrestrial environments - to beings with enhanced abilities.
In the future, could such beings be evolved from human subjects to be adapted to survive in previously inhospitable environments such as space, or could "cyber-warriors" with superhuman skills be created to perform in battle? These days, it seems that our scientific capabilities are limited only by our imagination; let us hope that the new technologies are used enhance our societies, and not destroy them.
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