Tag Archives: nanorobot
A rectangular robot as tiny as a few human hairs can travel throughout a colon by doing back flips, Purdue University engineers have demonstrated in live animal models. Why the back flips? Because the goal is to use these robots to transport drugs in humans, whose colons and other organs have rough terrain. Side flips work, too. Why a back-flipping robot to transport drugs? Getting a drug directly to its target site could remove side effects, such as hair loss or stomach bleeding, that the drug may otherwise cause by interacting with other organs along the way.
The study, published in the journal Micromachines, is the first demonstration of a microrobot tumbling through a biological system in vivo. Since it is too small to carry a battery, the microrobot is powered and wirelessly controlled from the outside by a magnetic field.
“When we apply a rotating external magnetic field to these robots, they rotate just like a car tire would to go over rough terrain,” said David Cappelleri, a Purdue associate professor of mechanical engineering. “The magnetic field also safely penetrates different types of mediums, which is important for using these robots in the human body.”
The researchers chose the colon for in vivo experiments because it has an easy point of entry – and it’s very messy. “Moving a robot around the colon is like using the people-walker at an airport to get to a terminal faster. Not only is the floor moving, but also the people around you,” said Luis Solorio, an assistant professor in Purdue’s Weldon School of Biomedical Engineering. “In the colon, you have all these fluids and materials that are following along the path, but the robot is moving in the opposite direction. It’s just not an easy voyage.”
But this magnetic microrobot can successfully tumble throughout the colon despite these rough conditions, the researchers’ experiments showed. The team conducted the in vivo experiments in the colons of live mice under anesthesia, inserting the microrobot in a saline solution through the rectum. They used ultrasound equipment to observe in real time how well the microrobot moved around.
In 1959, former Cornell physicist Richard Feynman delivered his famous lecture “There’s Plenty of Room at the Bottom,” in which he described the opportunity for shrinking technology, from machines to computer chips, to incredibly small sizes. Well, the bottom just got more crowded. A Cornell-led collaboration has created the first microscopic robots that incorporate semiconductor components, allowing them to be controlled – and made to walk – with standard electronic signals. These robots, roughly the size of paramecium, provide a template for building even more complex versions that utilize silicon-based intelligence, can be mass produced, and may someday travel through human tissue and blood.
The collaboration is led by Itai Cohen, professor of physics, Paul McEuen, the John A. Newman Professor of Physical Science – both in the College of Arts and Sciences – and their former postdoctoral researcher Marc Miskin, who is now an assistant professor at the University of Pennsylvania.
The walking robots are the latest iteration, and in many ways an evolution, of Cohen and McEuen’s previous nanoscale creations, from microscopic sensors to graphene-based origami machines. The new robots are about 5 microns thick (a micron is one-millionth of a meter), 40 microns wide and range from 40 to 70 microns in length. Each bot consists of a simple circuit made from silicon photovoltaics – which essentially functions as the torso and brain – and four electrochemical actuators that function as legs. As basic as the tiny machines may seem, creating the legs was an enormous feat.
“In the context of the robot’s brains, there’s a sense in which we’re just taking existing semiconductor technology and making it small and releasable,” said McEuen, who co-chairs the Nanoscale Science and Microsystems Engineering (NEXT Nano) Task Force, part of the provost’s Radical Collaboration initiative, and directs the Kavli Institute at Cornell for Nanoscale Science.
“But the legs did not exist before,” McEuen said. “There were no small, electrically activatable actuators that you could use. So we had to invent those and then combine them with the electronics.”
The team’s paper, “Electronically Integrated, Mass-Manufactured, Microscopic Robots,” has been published in Nature.
Researchers have harnessed the latest nanofabrication techniques to create bug-shaped robots that are wirelessly powered, able to walk, able to survive harsh environments and tiny enough to be injected through an ordinary hypodermic needle.
“When I was a kid, I remember looking in a microscope, and seeing all this crazy stuff going on. Now we’re building stuff that’s active at that size. We don’t just have to watch this world. You can actually play in it,” said Marc Miskin, who developed the nanofabrication techniques with his colleagues professors Itai Cohen and Paul McEuen and researcher Alejandro Cortese at Cornell University while Miskin was a postdoc in the laboratory for atomic and solid state physics there. In January, he became an assistant professor of electrical and systems engineering at the University of Pennsylvania.
Miskin will present his microscopic robot research on this week at the American Physical Society March Meeting in Boston. He will also participate in a press conference describing the work. Information for logging on to watch and ask questions remotely is included at the end of this news release.
Over the course of the past several years, Miskin and research colleagues developed a multistep nanofabrication technique that turns a 4-inch specialized silicon wafer into a million microscopic robots in just weeks. Each 70 micron long (about the width of a very thin human hair), the robots’ bodies are formed from a superthin rectangular skeleton of glass topped with a thin layer of silicon into which the researchers etch its electronics control components and either two or four silicon solar cells — the rudimentary equivalent of a brain and organs.
Robots are built massively in parallel using nanofabrication technology: each wafer holds 1 million machines
“The really high-level explanation of how we make them is we’re taking technology developed by the semiconductor industry and using it to make tiny robots,” said Miskin.
Each of a robot’s four legs is formed from a bilayer of platinum and titanium (or alternately, graphene). The platinum is applied using atomic layer deposition. “It’s like painting with atoms,” said Miskin. The platinum-titanium layer is then cut into each robot’s four 100-atom-thick legs. “The legs are super strong,” he said. “Each robot carries a body that’s 1,000 times thicker and weighs roughly 8,000 times more than each leg.”
The researchers shine a laser on one of a robot’s solar cells to power it. This causes the platinum in the leg to expand, while the titanium remains rigid in turn, causing the limb to bend. The robot’s gait is generated because each solar cell causes the alternate contraction or relaxing of the front or back legs. The researchers first saw a robot’s leg move several days before Christmas 2017. “The leg just twitched a bit,” recalled Miskin. “But it was the first proof of concept — this is going to work!”
Teams at Cornell and Pennsylvania are now at work on smart versions of the robots with on-board sensors, clocks and controllers. The current laser power source would limit the robot’s control to a fingernail-width into tissue. So Miskin is thinking about new energy sources, including ultrasound and magnetic fields, that would enable these robots to make incredible journeys in the human body for missions such as drug delivery or mapping the brain.
“We found out you can inject them using a syringe and they survive — they’re still intact and functional — which is pretty cool,” he said.
Engineers at the University of California San Diego have developed tiny ultrasound-powered robots that can swim through blood, removing harmful bacteria along with the toxins they produce. These proof-of-concept nanorobots could one day offer a safe and efficient way to detoxify and decontaminate biological fluids.
Researchers built the nanorobots by coating gold nanowires with a hybrid of platelet and red blood cell membranes. This hybrid cell membrane coating allows the nanorobots to perform the tasks of two different cells at once—platelets, which bind pathogens like MRSA bacteria (an antibiotic-resistant strain of Staphylococcus aureus), and red blood cells, which absorb and neutralize the toxins produced by these bacteria. The gold body of the nanorobots responds to ultrasound, which gives them the ability to swim around rapidly without chemical fuel. This mobility helps the nanorobots efficiently mix with their targets (bacteria and toxins) in blood and speed up detoxification.
The work, published May 30 in Science Robotics, combines technologies pioneered by Joseph Wang and Liangfang Zhang, professors in the Department of NanoEngineering at the UC San Diego Jacobs School of Engineering. Wang’s team developed the ultrasound-powered nanorobots, and Zhang’s team invented the technology to coat nanoparticles in natural cell membranes.
SEM image of a MRSA bacterium attached to a hybrid cell membrane coated nanorobot
“By integrating natural cell coatings onto synthetic nanomachines, we can impart new capabilities on tiny robots such as removal of pathogens and toxins from the body and from other matrices,” said Wang. “This is a proof-of-concept platform for diverse therapeutic and biodetoxification applications.”
“The idea is to create multifunctional nanorobots that can perform as many different tasks at once,” adds co-first author Berta Esteban-Fernández de Ávila, a postdoctoral scholar in Wang’s research group at UC San Diego. “Combining platelet and red blood cell membranes into each nanorobot coating is synergistic—platelets target bacteria, while red blood cells target and neutralize the toxins those bacteria produce.”