At a high level, programmable matter can be viewed as an intelligent, or programmable, material that contains the actuation and sensing mechanisms to “morph” into desirable/useful shapes under software control, or in reaction to external stimuli. The Defense Advanced Research Projects Agency in 2007 provided the vision and the concept of “Programmable Matter – the next revolution in materials”. Programmable Matter is a user-programmed smart material that adapts to changing conditions, in order to maintain, optimize, or even create a whole new functionality, using means that are intrinsic to the material itself.
Programmable Matter would allow building materials and even smart machines that adapt to their surroundings, such as an airplane wing that adjusts its surface properties in reaction to environmental variables, Better tools, at lower cost, that last longer and operate under all conditions.
They would allow us to create many more everyday objects capable of adapting to our shifting tasks, needs and desires. We could reconfigure our living room by ordering four chairs to reshape themselves into a table. The materials in a building could automatically respond to changes in the weather. The universal spare part that assumes the right size, shape, compliance – and function – to repair anything, clothing that maintained a normal body temperature in both the arctic and the desert.
Daniela Rus, director of the computer science and artificial intelligence laboratory at the Massachusetts Institute of Technology, envisions origami bots that can shape themselves into tools to perform medical procedures or deliver drugs inside the body. In a demonstration by her team in May 2016, a tiny origami bot made from pig intestine was able to unfold itself from a swallowed capsule in a simulated stomach and move across the stomach wall with the help of an external magnet.
The military utility can be endless: Airplane wings that change shape in flight to achieve enhance performance as an automatic response to changing speed, altitude; All-terrain vehicles whose tires change shape/traction depending on road/weather/ terrain conditions; Soldier’s gear that adapt to the changing environment or requirements; Self-healing materials, e.g., micro-cracks self-healing on aircrafts, roads, bridges, and equipment; Self-destructing materials for information security and protection of confidential materials, universal spare parts etc.
Researchers are developing Programmable material using two approaches , one being Engineers’ top-down approaches to programmable matter will build on existing developments in robotic technology. But there are also bottom-up strategies, using nanoscale particles or even molecules. For example, there is intense research being done on self-propelled or “living” colloids: particles perhaps a hundred or so nanometers across that have their own means of propulsion, such as chemical reactions that release gas.
The chemistry Nobel laureate Jean-Marie Lehn and others argued that chemists would use the principles of self-organization to design molecules imbued with the information they needed to spontaneously assemble themselves into complex structures. In the 1980s, Lehn began calling this “informed matter,” which would be a kind of programmable matter constructed at the atomic and molecular scale.
Researchers have also been studying ways to turn DNA itself into a kind of programmable material that could be made to assemble into specific configurations using the same chemical principles that bind the double helix of the genome. In this way, scientists have woven strands of DNA into complex nanoscale shapes: boxes with switchable lids, letters of the alphabet, even tiny world maps. By supplying and removing “fuel strands,” which can temporarily stick to and change the shape of other strands, it’s even possible to make molecular-scale machines that move.
Programmable materials using DNA
Researchers have engineered tiny gold particles that can assemble into a variety of crystalline structures simply by adding a bit of DNA to the solution that surrounds them. Down the road, such reprogrammable particles could be used to make materials that reshape themselves in response to light, or to create novel catalysts that reshape themselves as reactions proceed.
“This paper is very exciting,” says Sharon Glotzer, a chemical engineer at the University of Michigan, Ann Arbor, who calls it “a step towards pluripotent matter.” David Ginger, a chemist at the University of Washington, Seattle, agrees: “This is a proof of concept of something that has been a nanoparticle dream.” Neither Glotzer nor Ginger has ties to the current research.
Mirkin and his colleagues set out to create transmutable nanoparticles that, once formed, could be assembled into any one of a wide variety of building blocks that could then form crystalline materials. They coated gold nanoparticles with DNA linked like “hairpins,” single strands of DNA in which the end sticking out from the nanoparticle loops back and binds to a portion of the DNA closer to the particle.
In this “closed” state, the hairpin DNA can’t bind to the DNA on other nanoparticles. But the researchers added another set of short DNA strands to their solution that were programmed to bind to the portion of the hairpins stuck to the nanoparticles. This released the end of the hairpin, creating a “sticky end” that was now free to bind to a complementary strand on another nanoparticle. The sequence of these sticky ends could be programmed to cause them to bind either to similar-sized particles or to larger ones. The team also showed that it could combine multiple types of DNA hairpins. These could be released separately, on individual nanoparticles, thereby allowing the researchers to choose exactly which partners a nanoparticle will assemble with as a crystal grows.
The team also showed that it could combine multiple types of DNA hairpins. These could be released separately, on individual nanoparticles, thereby allowing the researchers to choose exactly which partners a nanoparticle will assemble with as a crystal grows.
The researchers also added more control over what crystals formed by changing the length of the DNA hairpins, the concentration at which they were assembled around the particles, and the concentration of different types of particles. They report in Science that they used these different knobs to create 10 different crystals. But according to Mirkin, his team already has the ability to cause particles to assemble into more than 500 different crystal forms. “This gives us the ability to make materials by design,” he says.
That ability should prove particularly useful in designing new optical materials, which depend on tight control over the spacing of nanoparticles in a crystal to determine what colors of light they transmit, reflect, and even emit. The new process allows for such control, Mirkin says. And much as in living organisms, it shows that a little bit of DNA can make a big difference.
Programmable materials’ showing future potential for industry
New research has shown that honeycomb “cellular” materials made of a shape-memory polymer might be programmed for specific purposes, from shock-absorbing football helmets to biomedical implants.
“We are introducing a new class of programmable materials whose effective mechanical properties can be modified after fabrication without any additional reprocessing,” said Pablo Zavattieri, an associate professor in Purdue University’s Lyles School of Civil Engineering. “The idea is that you might mass produce the basic material, and it has many potential uses because you can change it later for application A or application B.”
Such an approach might be used for noise-absorbing “acoustic metamaterials” that could be tuned after manufacture to absorb specific frequencies. Other potential long-term innovations include stealthy surfaces that don’t reflect radar waves for military applications, energy-absorbing cushions in football helmets, foams for automotive seating that might be adjusted for specific people based on their weight, and biomedical implants adjusted to match the stiffness of bone and other tissues. The materials might be reprogrammable, as well, meaning they could be altered to suit changing requirements, Zavattieri said.
In new findings, the researchers showed they could create programmable cellular materials by introducing deliberate defects to the unit cells. Two types of the honeycomb programmable materials were studied: one having hexagonal cells and the other having cells in a kagome pattern.
“In this case we call defects a good thing because they provide desirable changes in the material cell structure,” said postdoctoral research associate David Restrepo. “This is not intuitive because usually you try to avoid defects. If you have a hexagon, you want the cells to be perfect hexagons. We wanted to look at it another way. We said, if you deformed the hexagon, this could allow you to tune the properties of your material, so these imperfections are actually a good thing.”
“Of course, the feasibility of these types of applications may require additional research,” Zavattieri said. “For example, we are not there yet, but say you have a room and you want to shield it from noise. You might put this metamaterial in the walls so that it absorbs certain frequencies. But then say you want to adjust it to cancel out higher frequencies, so you might be able to tune it. It sounds like science fiction, but it’s getting within reach.”
Material properties depend on the shape of the unit cells and the makeup and thickness of the walls separating each cell. Findings showed that compressing the materials by 5 percent results in a 55 percent increase in stiffness, meaning it might be adapted for a range of applications. “That is pretty impressive because ordinarily you would have to fabricate a new material with at least twice the thickness of the walls to obtain a material with a 50 percent increase on stiffness,” Restrepo said.
Reconfiguring Active Particles into Dynamic Patterns
Researchers from the Korean Institute for Basic Science, the Department of Energy, the National Science Foundation, and Northwestern’s Materials Research Center, who were led by Dr Erik Luijten of Northwestern University, created, a set of self-propelled small spheres known as ‘Janus colloids’ which were able to arrange themselves into various patterns when exposed to an electric field. Janus colloids have two sides – one with a positive charge, and the other with a negative charge.
Because of this ‘broken symmetry’, when the colloids are exposed to an electric field, the charges on the particle change, causing electrostatic interactions between different colloids. This means that some particles repel each other, some attract to one another and others remain neutral. As a result, the spheres automatically form into patterns, such as a chain, a sphere or a cluster.
“Colloids are a great model system,” Luijten said. “Real materials, such as molecules, are very difficult to see and manipulate. These colloids have similar behaviors but on timescales and length scales that we can access. Even though they are simple, their behavior is representative for systems.”
“We have identified the minimal ingredients needed for all these different behaviors,” said Luijten, professor of materials science and engineering and engineering sciences and applied mathematics. “Now we can change how this dynamic system moves.”
“We are taking small steps toward encouraging lifelike behavior in materials,” said Granick, who directs the IBS Center for Soft and Living Matter. “We are already beginning to see that active materials can behave intelligently.”
This discovery could have various applications in optics, structural materials, microfuidic devices, sensors, and robotics. It could be used for drug delivery. A drug could be put inside particles, for example, that cluster into the spot of delivery. Or changes in the environment could be sensed if the system suddenly switches from swarming to forming chains.
“If you want to complete tasks on the micron scale, it’s difficult to insert a chip into a particle or program a particle that small,” said Han. “So it’s necessary to find the simplest way to control all those patterns.”
Light helps develop, activate and control programmable materials
Light of a certain wavelength can be used to put so-called active materials into motion and control their movement. In the future, this discovery can become significant in widely different areas such as environmental protection, medicine and the development of new materials which can be programmed.
Joakim Stenhammar at Lund University in Sweden led the study where he, together with colleagues from universities in Düsseldorf, Edinburgh and Cambridge, developed a model in which patterns of light control the movement of active particles. The light makes synthetically produced particles as well as microorganisms, such as bacteria and algae, spontaneously form into something that can be compared to a pump.
This is a relatively new research field, but there are many ideas for its future areas of application. Active particles can move with the help of fuel, for example sugar. One possible application is to have active particles deliver pharmaceutical substances or nanosensors to specific parts of the body. Within environmental science, the active particles could be compared to targeted robots that can locate oil spills and then release chemicals to break down any contamination.
“Our strategy has the potential of developing into an inexpensive and simple way to pump and control bacteria and other active materials”, says Joakim Stenhammar.
He finds that its greatest potential is within materials science. Using active particles to construct programmable materials can become a reality. By changing the external conditions, it may be possible to change the structure, properties and function of a material.
“Our results show how the properties of active particles can be used to design new materials that we are unable to produce today”, says Joakim Stenhammar.
MIT’s Programmable Materials
The MIT Self-Assembly Lab (under the direction of Skylar Tibbits) has been developing a variety of programmable materials, including textiles and flexible carbon fiber. MIT’s Self-Assembly Lab has developed materials that can be programmed to transform their shape autonomously — from flexible carbon fibre and hybrid plastics to wood grains and textiles. They have developed a system to produce programmable carbon fiber material that can fold, curl, twist and respond to a variety of activation energies.
Programmable carbon fiber enables a wide range of applications from morphable airplane flaps to self-regulating air intake valves, adaptive aerodynamics, tunable stiffness structures and a variety of other dynamic applications.
“Self-Assembly is a process by which disordered parts build an ordered structure through only local interaction. In self-assembling systems, individual parts move towards a final state, wheras in self-organizing systems, components move between multiple states, oscillate and may never come to rest in a final configuration.”
“From a military perspective, Programmable Matter is the ultimate way to prevent technological surprise – by having materials, such as polymers, metals, or composites, adapt to future operational environments”, according to Dr. Mitchell Zakin, Program Manager, Defense Sciences Office.
Funding from DARPA and the Army Research Lab has accelerated the work in the past two years. Engineers are now working toward self-assembling pop-up bridges, uniforms that adjust their insulation to individual biometrics, and camouflage that change to match its surroundings. DARPA is also developing shape-shifting robots that can flow like mercury through small openings to sneak into caves and bunkers.
As MIT professor Neil Gershenfeld notes, programmable matter will contain a mind of its own—it will be self-aware. Instead of forward deploying soldiers, the military would have an in theater, self-generating, self-aware, military capability, along with a seemingly endless supply of reserves. However for Military the PM would also multiply the security threats like Cyber threats can lead to physical destruction, loss of life and National Security
Thus, programmable matter and 4D printing, are creating a new class of disruptive military technologies far beyond 3D printing. However, solving many challenges and further extensive research is needed before PM become technically feasible in numerous systems and thus widely adopted.
Project Cyborg is a cloud-based meta-platform of design tools for programming matter across domains and scales. Project Cyborg provides elastic cloud-based computation in a web-based CAD shell for services such as modeling, simulation and multi-objective design optimization.. Cyborg allows individuals or groups to create specialized design platforms specific for their domains, whatever their domains happen to be, from nanoparticle design to tissue engineering, to self-assembling human-scale manufacturing.
Working with the design software company Autodesk, a project to create a self assembling 3D object from individual and unconnected parts was conceived and built. It used random movement to successfully assemble a regular 3D model. The team then looked at a larger version that could create furniture inside a kind of tombola spinner.
There is an unprecedented revolution happening at the biological and nano-scale, says Tibbits, and this is giving us the ability to programme physical and biological materials to change shape, properties and to compute.
One vision of the future is building PM is with a suite of multiple voxels with different forms and functions that are custom-designed, easily deposited, and then programmed for specific applications, similar to Biological domain where only twenty-two building blocks, the amino acids, in different permutations give rise to a myriad of proteins and eventually to 14 million life species.