If you've ever consumed the same round tablet in hopes of curing everything from stomachaches to headaches, you already know that medications don't have to treat specific areas of pain. While over-the-counter drugs have long been used to treat a variety of diseases, biomedical researchers have only just begun to explore better targeted drug delivery strategies when treating more complex medical conditions such as cardiovascular disease or cancer.
Millirobot is a potential breakthrough in this burgeoning field of biomedicine. These fingertip-sized robots have the potential to save lives in the future by crawling, turning, and swimming into tight spaces on missions to monitor internal affairs or deliver drugs.
Leading research on this subject, Stanford University mechanical engineer Renee Zhao is working on several milirobot designs at the same time.
Supporting robots with magnetic fields that can be applied instantly to generate torque in their continuous movement, change the way they move, can overcome obstacles in the body and autonomous movements in different locomotive situations. In other words, studies are carried out on the need for a robot to be a multi-tasking in a sense.
By simply changing the strength and direction of the magnetic field, Zhao's team could make the robot reach the desired location in a single leap over distances of ten times the robot's length.
Magnetic actuation is a critical part of his research, as it allows for independent control for non-invasive operation and allows compaction by isolating the control unit from the device.
"It's the most robust and multifunctional untethered robot we've ever made," Zhao said of their newest robot, appearing this month in Nature Communications.
This new “spinning wireless amphibious origami millirobot” is as versatile as it looks. It is a single beautifully designed unit that can move rapidly over the slippery, rough surfaces of an organ and move wirelessly as it swims through human fluids and transports liquid medicines.
Instead of swallowing pills or injecting liquids, this robot “retains the drug until it reaches its target and then releases a highly concentrated drug,” according to Zhao, an assistant professor of mechanical engineering. “This is how our robot delivers targeted drug delivery.”
According to Zhao, what makes this amphibious robot unique is that it goes beyond most origami-based robot designs that rely solely on origami's foldability to regulate how a robot shapes and moves.
In addition to considering how folding might allow the robot to perform certain tasks, the Zhao team also studied how the precise proportions of each fold affect the robot's rigid motion when the robot is not folded.
As a result, the robot's unfolded form was, in a sense, designed to propel it around.
Such broad thinking has allowed researchers to make greater use of materials without adding bulk, and in Zhao's world, the more functionality available from a single structure in robot design, the less invasive the medical procedure.
The integration of various geometric features is another unique aspect of robot design. A longitudinal opening in the middle of the robot and sloping side slits reduced water resistance, helping the robot swim better.
“This design creates a negative pressure in the robot, allowing it to swim quickly while also providing suction for cargo pickup and transport,” said Zhao. “We take full advantage of the geometric properties of this little robot and explore this single structure for a variety of applications and functions.”
Zhao Lab is examining how to improve existing treatments and procedures by developing new technologies based on discussions with Stanford Department of Medicine experts. If Zhao's experiment is successful, it will not only provide robots with a viable means to effectively deliver medicine, but will also be able to carry equipment or cameras around the body, potentially radically changing how doctors evaluate patients. The company is also looking into eliminating the need to cut organs by using ultrasound imaging to track where robots go.
While we won't see milirobots like Zhao's in real-world situations until more is understood about optimal design and imaging best practices, the lab at Nature Communications, the first swimmer of its kind, is one of their most advanced robots. It is currently in the experimental stages, which precedes any live animal testing that will follow human clinical trials.
Meanwhile, Zhao's group is working to combine various revolutionary smart materials and structures into original designs that will eventually result in new biomedical devices. It also plans to continue downscaling its robots to conduct micro-scale biomedical research.
As an engineer, Zhao tries to create the most functional structures possible. The amphibious robot embodies this goal as it inspires his team to think more deeply about geometric features that other origami robot researchers have yet to prioritize. “We started looking at how it all worked together,” Zhao explained. "There's a very unique aspect of our work, and it also has a wide variety of biomedical applications."