Researchers at Cornell University are taking nanotechnology to a new level, developing cell-size robots for targeted drug delivery that can be powered and steered by ultrasound waves and air bubbles.
A team, led by Mingming Wu, professor of biological and environmental engineering in the College of Agriculture and Life Sciences, has closely studied bacteria, sperm, and cancer cells over the last decade to better understand how they move through the body and communicate with their surroundings.
This has guided their work in creating micro-robotic swimmers that can be remotely controlled to navigate the body, say to fight cancer on a cellular level, with this targeted drug delivery. It is believed it will create a more effective treatment with fewer side effects.
"For drug delivery, you could have a group of micro-robotic swimmers, and if one failed during the journey, that’s not a problem. That’s how nature survives," Wu said. "In a way, it’s a more robust system. Smaller does not mean weaker. A group of them is undefeatable. I feel like these nature-inspired tools typically are more sustainable because nature has proved it works."
Through trial and error, the team has been working to perfect how the micro-robots are powered and how they propel themselves.
"Bacteria and sperm basically consume organic material in the surrounding fluid, and that is sufficient to power them," Wu said. "But for engineered robots it’s tough, because if they carry a battery, it’s too heavy for them to move."
That's when they turned to the use of high-frequency sound waves.
Working with the Cornell NanoScale Science and Technology Facility (CNF), a new laser lithography system called a NanoScribe was used to create 3D nanostructures made with resins that repel water.
When the micro-robotic swimmer is submerged in a solution, tiny air bubbles are trapped in a pair of cavities etched in its back. Ultrasound waves are aimed at the robot, causing the air bubbles to oscillate and generate movement.
The challenge ahead will be to make the swimmers biocompatible and biodegradable. Reference
Biologically inspired micro-robotic swimmers remotely controlled by ultrasound waves
Tao Luo and Mingming Wu https://pubs.rsc.org/en/content/articlelanding/2021/LC/D1LC00575H