First, they walked. Then they saw the light. Now, mini biological robots have acquired a new trick: remote control.
Hybrid “eBiobots” are the first to combine soft materials, living muscle and microelectronics, said researchers at the University of Illinois Urbana-Champaign, Northwestern University and the collaborating institutions. They described their centimeter-sized biological machines in the journal Robotics science.
“The integration of microelectronics allows the merging of the biological world and the world of electronics, with many advantages of their own, to produce these bio-robots and electronic machines that could be useful for many future medical, sensor and environmental applications,” the study said. Co-Leader Rashid Bashir, professor of bioengineering at Illinois State and dean of the Grainger College of Engineering.
Bashir’s group pioneered the development of biobots, which are small biological robots powered by mouse muscle tissue grown on a soft, 3D-printed polymer skeleton. They demonstrated walking biorobots in 2012 and light-activated biorobots in 2016. Light activation gave researchers some control, but practical applications were limited by the question of how to deliver light pulses to biorobots outside of a laboratory environment.
The answer to this question came from Northwestern University professor John A. Rogers, a pioneer in flexible bioelectronics, who helped his team integrate small wireless microelectronics and small battery-free LEDs. This allowed the researchers to remotely control the eBiobots.
“This extraordinary combination of technology and biology opens up enormous opportunities in creating engineered systems that self-repair, learn, evolve, communicate and self-regulate. We feel it is a very fertile ground for future research with specific potential applications in biomedicine and environmental monitoring,” said Rogers, professor of materials science and engineering and biomedical engineering. Biology and Neurosurgery at Northwestern University and Director of the Querry Simpson Institute for Bioelectronics.
To give biorobots the freedom of movement required for practical applications, the researchers set out to ditch the bulky batteries and tethered wires. Co-first author Zhengwei Li, an assistant professor of biomedical engineering at the University of Houston, said the eBiobots use a receiver coil to harvest energy and provide a regulated output voltage to drive the tiny LEDs.
The researchers can send a wireless signal to the eBiobots that triggers the LEDs’ pulses. The LEDs stimulate the engineered, light-sensitive muscles to contract, moving the polymer legs so that the machines “run.” The tiny LEDs have been targeted so that they can activate specific parts of the muscles, making the eBiobot turn in the desired direction.
The researchers used computer modeling to improve the eBiobot’s design and integrate components for durability, speed, and maneuverability. Illinois professor of mechanical sciences and engineering Mattia Gazzola led the simulation and software design of the eBiobots. The iterative design and additive 3D printing of the scaffolds allowed for rapid cycles of experiments and improved performance, said Gazzolla and co-author Xiaotian Zhang, a postdoctoral researcher in Gazzolla’s lab.
The design allows for the potential for future integration of additional microelectronics, such as chemical and biological sensors, or 3D-printed scaffold parts for functions such as pushing or moving objects encountered by biorobots, said co-first author Youngdeok Kim, who completed the work as a graduate student at Illinois.
The researchers said that the integration of electronic sensors or biological neurons will allow eBiobots to sense and respond to toxins in the environment, disease biomarkers and more possibilities.
“By developing the first-ever hybrid bioelectronic robot, we are opening the door to a new paradigm of healthcare innovation applications, such as biopsies and on-site analysis, minimally invasive surgery or even cancer detection within the human body,” Lee said.
The National Science Foundation and the National Institutes of Health supported this work.