The key to making such tiny devices in large quantities lies in a method the team developed for controlling the natural fracturing process of atomically-thin, brittle materials, directing the fracture lines so that they produce miniscule pockets of a predictable size and shape. Embedded inside these pockets are electronic circuits and materials that can collect, record, and output data.
The novel process, called “autoperforation,” is described in a paper published today in the journal Nature Materials, by MIT Professor Michael Strano, postdoc Pingwei Liu, graduate student Albert Liu, and eight others at MIT.
The system uses a two-dimensional form of carbon called graphene, which forms the outer structure of the tiny syncells. One layer of the material is laid down on a surface, then tiny dots of a polymer material, containing the electronics for the devices, are deposited by a sophisticated laboratory version of an inkjet printer. Then, a second layer of graphene is laid on top.
People think of graphene, an ultrathin but extremely strong material, as being “floppy,” but it is actually brittle, Strano explains. But rather than considering that brittleness a problem, the team figured out that it could be used to their advantage.
“We discovered that you can use the brittleness,” says Strano, who is the Carbon P. Dubbs Professor of Chemical Engineering at MIT. “It’s counterintuitive. Before this work, if you told me you could fracture a material to control its shape at the nanoscale, I would have been incredulous.”
But the new system does just that. It controls the fracturing process so that rather than generating random shards of material, like the remains of a broken window, it produces pieces of uniform shape and size. “What we discovered is that you can impose a strain field to cause the fracture to be guided, and you can use that for controlled fabrication,” Strano says.
When the top layer of graphene is placed over the array of polymer dots, which form round pillar shapes, the places where the graphene drapes over the round edges of the pillars form lines of high strain in the material. As Albert Liu describes it, “imagine a tablecloth falling slowly down onto the surface of a circular table. One can very easily visualize the developing circular strain toward the table edges, and that’s very much analogous to what happens when a flat sheet of graphene folds around these printed polymer pillars.”
As a result, the fractures are concentrated right along those boundaries, Strano says. “And then something pretty amazing happens: The graphene will completely fracture, but the fracture will be guided around the periphery of the pillar.” The result is a neat, round piece of graphene that looks as if it had been cleanly cut out by a microscopic hole punch.
Because there are two layers of graphene, above and below the polymer pillars, the two resulting disks adhere at their edges to form something like a tiny pita bread pocket, with the polymer sealed inside. “And the advantage here is that this is essentially a single step,” in contrast to many complex clean-room steps needed by other processes to try to make microscopic robotic devices, Strano says.
The researchers have also shown that other two-dimensional materials in addition to graphene, such as molybdenum disulfide and hexagonal boronitride, work just as well.
Image Credit: YouTube/MIT
News This Week
From Frontiers Forum: How can research translate to R&D? Or a whole new business venture? In a panel session at Science Unlimited 2019, Holtzbrinck Publishing Group CEO Stefan von Holtzbrinck, Life Biosciences CEO [...]
More and more security holes are appearing in cryptocurrency and smart contract platforms, and some are fundamental to the way they were built. Early last month, the security team at Coinbase noticed something strange [...]
“The most crucial result of this work is the correlation between form and function in supercapacitor materials,” states first author Dina Ibrahim Abouelamaiem. She elaborates that “our research is driven by the need for [...]
“We’ll have nanobots that… connect our neocortex to a synthetic neocortex in the cloud. Our thinking will be a…. biological and non-biological hybrid.” Ray Kurzweil, TED 2014 UPDATE - June 18 2019 Since [...]
A new study by the Environmental Working Group reveals that: “Major food companies like General Mills continue to sell popular children’s breakfast cereals and other foods contaminated with troubling levels of glyphosate, the cancer-causing [...]
A nanotechnology treatment derived from bone marrow stem cells has reversed multiple sclerosis symptoms in mice and could eventually be used to help humans, according to a new study led by University of California, [...]
In a paper published this week in Nature ("Freestanding crystalline oxide perovskites down to the monolayer limit"), materials science researchers at the University of California, Irvine and other institutions unveil a new process for [...]
New research provides insight into the structure of silicon nanocrystals, a substance that promises to provide efficient lithium ion batteries that power your phone to medical imaging on the nanoscale. The research was conducted [...]
Several space missions, planned by both the European Space Agency and NASA, have their target set on Jupiter and its moons. The extraordinarily harsh radiation environments in the Jovian system will set some strict [...]
rance is clamping down on a common food additive that has been shown to be carcinogenic in animal studies. The ban of titanium dioxide, announced by the French government last month, follows a review [...]
Today’s societies critically depend on electronic systems. Past spectacular cyber-attacks have clearly demonstrated the vulnerability of existing systems and the need to prevent such attacks in the future. The majority of available cyber-defenses concentrate [...]
Researchers of the Nanoscience Center (NSC) at the University of Jyväskylä, Finland, and in the Xiamen University, China, have discovered how copper particles at the nanometre scale operate in modifying a carbon–oxygen bond when [...]
Cells in the body are wired like computer chips to direct signals that instruct how they function, research suggests (Nature Communications, “The cell-wide web coordinates cellular processes by directing site-specific Ca2+ flux across cytoplasmic [...]
We may be able to detect cancer soon by simply peeing on a stick. - Cancer is an aberrant function of a normal cell, where the regulators of that cell's dividing are broken [...]