The ability to self-repair damage is a fundamental property of organic life. But, for nonliving matter, like metals or rocks, any damage made to them is for keeps.
For things made from nonliving stuff, like cars, this is one of the occupational hazards of vehicle ownership. Repairs and replacement parts are constantly needed over time, adding to the cost of ownership over the vehicle's lifetime.
So, wouldn't it be great if some, or even all, parts of something like a car could be made of materials that could actually fix themselves?
While this might sound like complete science fiction, some exciting developments in self-healing materials might make this a reality one day!
Let's find out more.
Is there a self-healing car?
In short, at present, no.
While there is a plethora of "self-healing", non-organic materials currently in development, there is currently no means of bringing together a wide variety of materials into a single vehicle that can completely repair itself.
However, there are some interesting developments in this field that could be a sign of a potential future for self-healing cars.
One example is the Lamborghini Terzo Millennio Concept car. Announced in May of 2022, the Terzo Millennio Concept is currently in development by Lamborghini and the Massachusetts Institute of Technology (MIT). But more on that particular car later.
How do self-healing materials work?
In short, it really depends on what material type you are talking about.
The most common way to make a material that can heal itself is to put tiny capsules of healing agents right inside the material. The capsules break when the material is damaged, letting out the substance that fixes it (or fills gaps and voids).
While simple in concept, the size of the capsules is very important in this design since the material will be weakened if they are too big (for obvious reasons). They can also only be used once, which is not good if the material is likely to get damaged more than once, like, say an aircraft's wing.
Other options are also being explored, like materials that can fix themselves using vascular networks, like the veins on a leaf. When there is a break in these microvascular materials, a healing agent flows through the vascular network to fix the gap. Pretty neat, but it takes longer than other ways to fix something.
One problem with making self-healing materials for the auto industry is that it is much harder to make metals with these properties. Metal is used to make a lot of car parts, but it's hard to make a self-healing metal because of the atomic structure and nature of metals.
That being said, there are some interesting developments regarding the potential for self-healing aluminum. But, more on that later.
Because of this, design engineers often focus on polymers, rather than metals, when they do research in this field.
It is now possible to make a smart polymer that can change color, transparency, or shape in response to the environment and return to the way it was even if damaged. Even better, scientists have made smart polymers called "intrinsic polymers" that can fix themselves without help from the outside.
These intrinsic polymers can regenerate using dynamic chemical bonds within the material itself. This means their chemical bonds can essentially be broken and put back together again, and they can get back to how they were before they were damaged.
This could eventually prove very handy indeed for machinery and cars.
Can Lamborghini Terzo heal itself?
That is basically the idea, yes.
The Terzo Millennio, which means the "Third Millennium" in Italian, could be coming a lot sooner than many once thought.
Stefano Domenicali, who was the CEO of Lamborghini from 2016 to 2020, started the Terzo project in 2016. From the information available on this understandably secretive project, what may become the world's first self-healing car may actually be ready to go in 2030.
The development of this vehicle will certainly push the limits of science and technology but might usher in a new era of hyper-sustainable vehicles.
One of the key elements will be the use of nanotechnology, in this case, and more specifically, carbon nanotubes. Lamborghini is currently a leader in carbon fiber research and development, and it is now using the same nanotube technology to make cars that are strong, light, and, potentially, could actually fix themselves.
By sandwiching carbon nanotubes between layers of carbon fiber panels, the electricity-storing nanotubes can warm up and seal off micro-cracks, just like blood vessels do in the human body. By sending resin to the damaged spots, more damage can be stopped or lessened.
This has a lot of benefits, including making the structure stronger and saving time and money.
But that is just part of the story. The Terzo will also make liberal use of supercapacitors. These will let the car charge faster and use energy more efficiently.
At the same time, the car's body, which is made of carbon nanotubes, stores static electro-energy. This makes the whole body work like a bunch of supercapacitors. This will help make the car lighter by enabling energy storage to be more evenly distributed across the width and length of the vehicle.
As for the car's engine, it will likely be provided by electric motors located directly within the wheels. This will give the car better stability and handling, which could rival modern Formula One cars. Again, these will be supplied with power from supercapacitors.
Rumors also abound that the car will not only be able to heal itself but also drive itself too.
The Terzo Millennio will only be able to drive itself on a racetrack, but if all goes well, it is conceivable that future examples could be seen on the road.
What would a self-healing car need?
So, we've already detailed one example of a self-healing car currently in the works. But, what other systems/functions would a "true" self-healing car need?
Let's find out.
1. You'd need a way to figure out what's wrong
Fault finding or "injury" sensors would probably be a must. These can either be active sensors (constantly scanning critical parts) or could be more passive. Modern cars already have a vast suite of sensors and other systems to detect faults early, so we are more or less there with this sort of thing.
But, such systems can only provide a warning or put the engine into a "safe mode". If they could also activate some form of repair system too, that would clearly be of great benefit.
For some materials, like self-healing foams, the need for sensors of this kind may be redundant, as the material will simply "recover" on its own accord without being "told" to do something. A more active monitoring system would probably be required for other systems, like the car's delicate electronics. Amazingly, something like this is already in the works - sort of.
While a little esoteric regarding cars, one example is a new kind of "touchy-feely" self-healing polymer. Designed more specifically as a potential future prosthetic for amputees, the technology could be adapted to allow cars to "feel" when they get damaged and trigger a repair function (if needed).
2. Its metal bits would need to fix themselves
The idea that these could miraculously fix themselves would be excellent news for anyone who has ever dented their car's bodywork. But could this ever be possible?
We've already touched on the self-healing nanotubes for the Lamborghini Terzo, but other options are in the works too.
For example, scientists are looking at how self-healing polymeric coatings could be used in deep-sea and space exploration. In these situations, a coating would cut maintenance costs by a considerable amount since these are hard places to fix.
These coatings are being made for very harsh environments, but if they work well in these areas, they may also be used in other places. Some of the coatings that are being made protect against corrosion, while others protect against scratches.
This sounds just perfect for the average car user too.
Increasing costs for repainting following repair or to prevent corrosion is one reason for some high car maintenance costs. If improvements in self-healing polymeric coatings make it possible to make paint that can handle small scratches and resist corrosion, this could change how much car owners have to spend on repairs. Even something as simple as tougher paint could make cars last longer, which would be good news for people who use them.
All is well and good, but most cars today tend to be made of metal. Well, it just so happens that plans are afoot to make self-healing metals too.
As we discussed, self-healing aluminum may be with us in the near future.
Material scientists in Australia have developed a first-of-its-kind way to look into the cause of metal fatigue (the most common reason for metal failure over time), which they called precipitate-free zones (PFZs). These are weak spots that form in aluminum alloys when the stresses change. They start as small areas where the material is flexible and grow into cracks that eventually spread and weaken the material.
To mitigate this, the team found a way to "catch" new particles that form when stress is put on the aluminum alloy. They were able to use the particles they had caught to fix the weak spots. By doing this, they significantly slowed down the development of cracks in the metal structure.
The researchers say that by changing the initial microstructure of the metal in this way, they can make aluminum alloys much more resistant to wear and tear. The fatigue lifespan of high-strength aluminum alloys, which are known to be weak, could be increased by as much as 25 times.
This could be an avenue to explore for cars too, if car makers have their hearts set on keeping vehicles' shells made from metal.
For other parts, like the car's mechanical parts, metal fatigue tends to be the number one reason for mechanical faults over time. If self-healing techniques can be developed for these parts too, it could drastically improve the average lifetime of machinery and vehicles like cars.
3. It would be great if car tires could self-heal too
Bodywork aside, other parts of a car could benefit from being able to heal themselves too. Self-healing tires, for example, would be handy.
Amazingly, something like this is also currently in development. Researchers at Harvard University have made a tough rubber that can actually heal itself. They made a molecular rope by putting together covalent and reversible bonds to do so. The result is a clear rubber that can heal itself by spreading stress throughout the material.
Most of the time, when rubber cracks, it is because stress has built up in one spot. This is reduced in this case because the molecular structure of the self-healing rubber spreads the stress out through a network of crazes, which are cracks connected by fibers.
By letting the stress spread out more evenly through the material, self-healing rubber is much better able to handle force.
Tires made from this kind of rubber would be able to handle more stress than the ones we have now and would probably last longer, even in harsh environments. Some people have even said that if a tire was made of rubber that could fix itself, it wouldn't need to be replaced immediately if it got cut.
4. Having some way to fix the electronics would also be helpful
So, we have some potential for fault finding and some options for self-healing the car's bodywork and tires, but what about other systems on the vehicle?
How about the electronics?
Well, believe it or not, work is also underway in this area too. Polyamide materials, like ForTii 11, are the toughest material for making electrical parts for cars. This high-temperature polyamide has flame retardant grades with and without halogens and works well in harsh conditions.
This makes the product less likely to crack and makes it more reliable in terms of thermal shock aging.
Other potentials include a material called Healable, Low-Field Illuminating Optoelectronic Stretchable (HELIOS). The novel invention is stretchable, self-healing, and even illuminating while also able to conduct electricity.
The team behind its development started out by making a material that could heal itself and had a very high dielectric permittivity. They did this by mixing fluoroelastomers and surfactants in a special way.
This led to the creation of a material that lets devices turn on at four times lower voltages and light up more than 20 times brighter. Because it uses so little power, HELIOS can keep running for longer.
It can be used safely in interfaces between humans and machines and can be powered wirelessly. Last but not least, the material can't be torn or punctured because the bonds between its molecules are reversible and easy to fix - all excellent properties for a potentially self-healing electrical system.
Other developments are also being made in self-healing liquid metal composites, which can also be used to make soft, recyclable electrical circuits. These composites do not break even when punctured and can be repeatedly stretched without losing their electrical conductivity.
Another alternative, of course, is to dispense entirely with fixed wires for the car's electrical components by using devices like photoelectric circuits.
5. How about the battery?
With the rise in popularity of electric cars, the need for long-lasting and potentially limitless or self-healing batteries would be a very welcome development. But are there any options?
As it happens, yes, there are.
One option might be to combine organic molecules with machines. Called biobatteries, these innovative pieces of kit mimic how living cells generate electricity to produce long-lasting and theoretically, never-ending power supplies.
The secret? Glucose. This is one of the most common energy sources used by living beings. When enzymes in the cell break down glucose, the process also releases electrons that can be used to power devices.
"A photosynthetic bacteria generate organic food that is used as a nutrient for the other bacterial cells beneath. At the bottom is the electricity-producing bacteria, and the middle bacteria generate some chemicals to improve the electron transfer," explains Seokheun Choi, a professor at the Thomas J. Watson College of Engineering and Applied Sciences at Binghamton University, who led the research team.
While these kinds of batteries currently only produce a small amount of power, future developments and scaling might be able to produce self-healing, long-lasting, organic-based batteries for future cars.
Other than that, many new kinds of batteries are currently developing that, while not necessarily self-healing, could last for much longer than current lithium-ion or acid batteries.
6. But, what about the windscreen?
Great, so we've sorted the fault-finding, electrics, bodywork, tires, and battery. But, what about another commonly broken or damaged part in cars; the windows?
Well, there might be some hope here too.
Materials scientists are working on what has been the dubbed the "world's toughest self-healing material" and it could be used as a replacement for traditional glass.
Researchers at the Indian Institute of Science Education and Research (IISER) developed the material using a piezoelectric organic material, which turns mechanical energy into electrical energy and vice versa, to make needle-shaped crystals less than 2 mm long and 0.2 mm wide.
Because of how the molecules are arranged in specially made crystals, there is a strong force of attraction between the two surfaces. Every time a crack occurs, the pieces stick back together on their own, without needing heat or other outside forces that most self-healing materials would need.
According to lead researcher Professor Chilla Malla Reddy of IISER, "Our self-healing material is 10 times harder than others, and it has a well-ordered internal crystalline structure that is favored in most electronics and optical applications."
“I can imagine applications for an everyday device,” added Bhanu Bhushan Khatua, a team member from IIT Kharagpur. "Such materials could be used for mobile phone screens that will repair themselves if they fall and develop cracks" he said.
While currently aimed at the smart device market, there is little reason a similar technique couldn't one day create windows for use in cars. Who knows, windscreens and windows of future cars might also become more interactive too (safety issues aside)?
And that, self-healing car hopefuls, is your lot for today.
There aren't any self-repairing cars on the market yet, but research into self-healing materials is getting better every year.
In the next few decades, there might be cars that never get scratched or that can fix their damage. Even though the technology is still being worked on, scientists and engineers in the field of materials are, in a sense, making science fiction come true.