I’ve heard of biomimetics – machinery and synthetics that can imitate organic materials – but this really takes the cake! In an effort to pioneer components and devices that would posses the regenerative powers of skin, a Spanish researcher Ibon Odriozola – who works for the CIDETEC Centre for Electrochemical Technologies in Spain – has created a polymer that could lead to a future where repairing machinery is as easy as suturing an open wound.
Comprised of a poly (urea-urethane) elastomeric matrix, the material is basically a network of complex molecular interactions that will spontaneously cross-link to “heal” most any break. In this context, the word “spontaneous” means that the material needs no outside intervention to begin its healing process, no catalyst or extra reactant.
To experiment with the material, Odriozola cut a sample in half with a razor blade at room temperature. And in just two hours, the cut healed itself with 97% efficiency. The reaction, called a metathesis reaction, has led Odriozola to dub the material his “Terminator” polymer, in reference to you-know-who (pictured above). Though the transition process takes a little longer, and involves polymers instead of metal, the basic principle is the same.
Unlike other self-healing materials, this one requires no catalyst and no layering. In addition to being very impressive to behold, this technology can extend the life spans of plastics that are under regular stress. The group’s main goal now is to make a harder version, perhaps one that could be formed into such parts itself. As it exists today, the polymer is squishy and somewhat soft.
In addition, a good self-healing material like this is a boon for ongoing efforts to find a viable material for artificial skin. Self-healing technology could also open the door to growth materials, as new units of the matrix could be incorporated as the material stretches and tears on the microscopic level. This would be especially useful when it comes to artificial skin, since it could grow over time and remove the need for replacement.
And if the healing mechanism proves strong enough, it could even be used as an adhesive or a sealant in other materials and even electronics. Just think of it! Everything from windows, to personal devices, to joints that are in need of padding. A simple injection of this type of material, and the breaks and aches go away. And given the progress being made with androids and life-like robots, its use as a source for artificial skin could go a long way to making them anthropomorphic.
And as usual, there’s a cool demonstration video. Enjoy!
Nanotechnology has long been the dream of researchers, scientists and futurists alike, and for obvious reasons. If machinery were small enough so as to be microscopic, or so small that it could only be measured on the atomic level, just about anything would be possible. These include constructing buildings and products from the atomic level up, with would revolutionize manufacturing as we know it.
In addition, microscopic computers, smart cells and materials, and electronics so infinitesimally small that they could be merged with living tissues would all be within our grasp. And it seems that at least once a month, universities, research labs, and even independent skunkworks are unveiling new and exciting steps that are bringing us ever closer to this goal.
Once such breakthrough comes from the University of North Carolina at Chapel Hill, where biomedical scientists and engineers have joined forces to create the “smart sponge”. A spherical object that is microscopic — just 250 micrometers across, and could be made as small as 0.1 micrometers – these new sponges are similar to nanoparticles, in that they are intended to be the next-generation of delivery vehicles for medication.
Each sponge is mainly composed of a polymer called chitosan, something which is not naturally occurring, but can be produced easily from the chitin in crustacean shells. The long polysaccharide chains of chitosan form a matrix in which tiny porous nanocapsules are embedded, and which can be designed to respond to the presence of some external compound – be it an enzyme, blood sugar, or a chemical trigger.
So far, the researchers tested the smart sponges with insulin, so the nanocapsules in this case contained glucose oxidase. As the level of glucose in a diabetic patient’s blood increases, it would trigger the nanocapsules in the smart sponge begin releasing hydrogen ions which impart a positive charge to the chitosan strands. This in turn causes them to spread apart and begin to slowly release insulin into the blood.
The process is also self-limiting: as glucose levels in the blood come down after the release of insulin, the nanocapsules deactivate and the positive charge dissipates. Without all those hydrogen ions in the way, the chitosan can come back together to keep the remaining insulin inside. The chitosan is eventually degraded and absorbed by the body, so there are no long-term health effects.
One the chief benefits of this kind of system, much like with nanoparticles, is that it delivers medication when its needed, to where its needed, and in amounts that are appropriate to the patient’s needs. So far, the team has had success treating diabetes in rats, but plans to expand their treatment to treating humans, and branching out to treat other types of disease.
Cancer is a prime candidate, and the University team believes it can be treated without an activation system of any kind. Tumors are naturally highly acidic environments, which means a lot of free hydrogen ions. And since that’s what the diabetic smart sponge produces as a trigger anyway, it can be filled with small amounts of chemotherapy drugs that would automatically be released in areas with cancer cells.
Another exciting breakthrough comes from University of California at Berkeley, where medical researchers are working towards tiny, implantable sensors . As all medical researchers know, the key to understanding and treating neurological problems is to gather real-time and in-depth information on the subject’s brain. Unfortunately, things like MRIs and positron emission tomography (PET) aren’t exactly portable and are expensive to run.
Implantable devices are fast becoming a solution to this problem, offering real-time data that comes directly from the source and can be accessed wirelessly at any time. So far, this has taken the form of temporary medical tattoos or tiny sensors which are intended to be implanted in the bloodstreams. However, what the researchers at UofC are proposing something much more radical.
In a recent research paper, they proposed a design for a new kind of implantable sensor – an intelligent dust that can infiltrate the brain, record data, and communicate with the outside world. The preliminary design was undertaken by Berkeley’s Dongjin Seo and colleagues, who described a network of tiny sensors – each package being no more than 100 micrometers – in diameter. Hence the term they used: “neural dust”.
The smart particles would all contain a very small CMOS sensor capable of measuring electrical activity in nearby neurons. The researchers also envision a system where each particle is powered by a piezoelectric material rather than tiny batteries. The particles would communicate data to an external device via ultrasound waves, and the entire package would also be coated in a polymer, thus making it bio-neutral.
But of course, the dust would need to be complimented by some other implantable devices. These would likely include a larger subdural transceiver that would send the ultrasound waves to the dust and pick up the return signal. The internal transceiver would also be wirelessly connected to an external device on the scalp that contains data processing hardware, a long range transmitter, storage, and a battery.
The benefits of this kind of system are again obvious. In addition to acting like an MRI running in your brain all the time, it would allow for real-time monitoring of neurological activity for the purposes of research and medical monitoring. The researchers also see this technology as a way to enable brain-machine interfaces, something which would go far beyond current methods. Who knows? It might even enable a form of machine-based telepathy in time.
Sounds like science fiction, and it still is. Many issues need to be worked out before something of this nature would be possible or commercially available. For one, more powerful antennae would need to be designed on the microscopic scale in order for the smart dust particles to be able to send and receive ultrasound waves.
Increasing the efficiency of transceivers and piezoelectric materials will also be a necessity to provide the dust with power, otherwise they could cause a build-up of excess heat in the user’s neurons, with dire effects! But most importantly of all, researchers need to find a safe and effective way to deliver the tiny sensors to the brain.
And last, but certainly not least, nanotechnology might be offering improvements in the field of prosthetics as well. In recent years, scientists have made enormous breakthroughs in the field of robotic and bionic limbs, restoring ambulatory mobility to accident victims, the disabled, and combat veterans. But even more impressive are the current efforts to restore sensation as well.
One method, which is being explored by the Technion-Israel Institute of Technology in Israel, involves incorporating gold nanoparticles and a substrate made of polyethylene terephthalate (PET) – the plastic used in bottles of soft drinks. Between these two materials, they were able to make an ultra-sensitive film that would be capable of transmitting electrical signals to the user, simulating the sensation of touch.
Basically, the gold-polyester nanomaterial experiences changes in conductivity as it is bent, providing an extremely sensitive measure of physical force. Tests conducted on the material showed that it was able to sense pressures ranging from tens of milligrams to tens of grams, which is ten times more sensitive than any sensors being build today.
Even better, the film maintained its sensory resolution after many “bending cycles”, meaning it showed consistent results and would give users a long term of use. Unlike many useful materials that can only really be used under laboratory conditions, this film can operate at very low voltages, meaning that it could be manufactured cheaply and actually be useful in real-world situations.
In their research paper, lead researcher Hossam Haick described the sensors as “flowers, where the center of the flower is the gold or metal nanoparticle and the petals are the monolayer of organic ligands that generally protect it.” The paper also states that in addition to providing pressure information (touch), the sensors in their prototype were also able to sense temperature and humidity.
But of course, a great deal of calibration of the technology is still needed, so that each user’s brain is able to interpret the electronic signals being received from the artificial skin correctly. But this is standard procedure with next-generation prosthetic devices, ones which rely on two-way electronic signals to provide control signals and feedback.
And these are just some examples of how nanotechnology is seeking to improve and enhance our world. When it comes to sensory and mobility, it offers solutions to not only remedy health problems or limitations, but also to enhance natural abilities. But the long-term possibilities go beyond this by many orders of magnitude.
As a cornerstone to the post-singularity world being envisioned by futurists, nanotech offers solutions to everything from health and manufacturing to space exploration and clinical immortality. And as part of an ongoing trend in miniaturization, it presents the possibility of building devices and products that are even tinier and more sophisticated than we can currently imagine.
It’s always interesting how science works by scale, isn’t it? In addition to dreaming large – looking to build structures that are bigger, taller, and more elaborate – we are also looking inward, hoping to grab matter at its most basic level. In this way, we will not only be able to plant our feet anywhere in the universe, but manipulate it on the tiniest of levels.
As always, the future is a paradox, filling people with both awe and fear at the same time.
When it comes to modern research and development, biomimetics appear to be the order of the day. By imitating the function of biological organisms, researchers seek to improve the function of machinery to the point that it can be integrated into human bodies. Already, researchers have unveiled devices that can do the job of organs, or bionic limbs that use the wearer’s nerve signals or thoughts to initiate motion.
But what of machinery that can actually send signals back to the user, registering pressure and stimulation? That’s what researchers from the University of Georgia have been working on of late, and it has inspired them to create a device that can do the job of the largest human organ of them all – our skin. Back in April, they announced that they had successfully created a brand of “smart skin” that is sensitive enough to rival the real thing.
In essence, the skin is a transparent, flexible arrays that uses 8000 touch-sensitive transistors (aka. taxels) that emit electricity when agitated. Each of these comprises a bundle of some 1,500 zinc oxide nanowires, which connect to electrodes via a thin layer of gold, enabling the arrays to pick up on changes in pressure as low as 10 kilopascals, which is what human skin can detect.
Mimicking the sense of touch electronically has long been the dream researchers, and has been accomplished by measuring changes in resistance. But the team at Georgia Tech experimented with a different approach, measuring tiny polarization changes when piezoelectric materials such as zinc oxide are placed under mechanical stress. In these transistors, then, piezoelectric charges control the flow of current through the nanowires.
In a recent news release, lead author Zhong Lin Wang of Georgia Tech’s School of Materials Science and Engineering said:
Any mechanical motion, such as the movement of arms or the fingers of a robot, could be translated to control signals. This could make artificial skin smarter and more like the human skin. It would allow the skin to feel activity on the surface.
This, when integrated to prosthetics or even robots, will allow the user to experience the sensation of touch when using their bionic limbs. But the range of possibilities extends beyond that. As Wang explained:
This is a fundamentally new technology that allows us to control electronic devices directly using mechanical agitation. This could be used in a broad range of areas, including robotics, MEMS, human-computer interfaces, and other areas that involve mechanical deformation.
Not the first time that bionic limbs have come equipped with electrodes to enable sensation. In fact, the robotic hand designed by Silvestro Micera of the Ecole Polytechnique Federale de Lausanne in Switzerland seeks to do the same thing. Using electrodes that connect from the fingertips, palm and index finger to the wearer’s arm nerves, the device registers pressure and tension in order to help them better interact with their environment.
Building on these two efforts, it is easy to get a glimpse of what future prosthetic devices will look like. In all likelihood, they will be skin-colored and covered with a soft “dermal” layer that is studded with thousands of sensors. This way, the wearer will be able to register sensations – everything from pressure to changes in temperature and perhaps even injury – from every corner of their hand.
As usual, the technology may have military uses, since the Defense Advanced Research Projects Agency (DARPA) is involved. For that matter, so is the U.S. Air Force, the U.S. Department of Energy, the National Science Foundation, and the Knowledge Innovation Program of the Chinese Academy of Sciences are all funding it. So don’t be too surprised if bots wearing a convincing suit of artificial skin start popping up in your neighborhood!