Researchers find greater freedom of movement with muscle-powered robots

Welcome to the world of muscle-powered robots. No, we’re not quite at the level of Arnold Schwarzenegger in Terminator, but there has been a development that brings us one step closer. Researchers led by Northwestern University and the University of Illinois Urbana-Champaign have installed a remote control in a machine that combines soft materials (living muscle), with microelectronics in a hybrid dubbed “eBiobots”.

“Integrating microelectronics allows the merger of the biological world and the electronics world, both with many advantages of their own, to now produce these electronic biobots and machines that could be useful for many medical, sensing and environmental applications in the future,” says study co-leader Rashid Bashir, an Illinois professor of bioengineering and dean of the Grainger College of Engineering.

This study builds off previous years of research involving Bashir. Using small biological robots powered by mouse muscle tissue grown on a soft 3D-printed polymer skeleton, in 2012, they demonstrated walking biobots; in 2014, they developed the first self-propelled biohybrid robots that could swim and walk, and in 2016, they tested light-activated biobots. The 2016 study gave the researchers some control over the biobots, but practical applications were limited by how to deliver the light pulses to the biobots outside of a controlled lab setting.

But Northwestern professor John A. Rogers, a researcher in flexible bioelectronics, helped integrate tiny wireless microelectronics and battery-free micro-LEDs into Bashir’s biobots. This allowed the researchers to remotely control the contraptions, and thus, the testing of eBiobots were underway.

“This unusual combination of technology and biology opens up vast opportunities in creating self-healing, learning, evolving, communicating and self-organising engineered systems,” says Rogers. “We feel that it’s a very fertile ground for future research with specific potential applications in biomedicine and environmental monitoring.”

Researchers could now send wireless signals to the eBiobots to prompt the LEDs to pulse. The LEDs stimulate the light-sensitive engineered muscle to contract and subsequently move the polymer legs so that the machines can walk. The micro-LEDs are targeted so they can activate specific portions of muscle, making the eBiobot turn in the direction desired.

Part of the process also saw the team eliminate bulky batteries and tethering wires in order to facilitate practical freedom of movement this muscle offers the robot. The system instead uses a receiver coil to harvest power and provide a regulated output voltage to power the micro-LEDs, said co-first author Zhengwei Li, an assistant professor of biomedical engineering at the University of Houston.

Using computational modelling to optimise the eBiobot design and component, the design was made to allow possible future integration of additional microelectronics, the research team claim: like chemical and biological sensors and 3D-printed scaffold parts for functions like pushing or transporting things that the biobots encounter. They believe this integration of electronic sensors or biological neurons will allow the eBiobots to sense toxins in the environment, biomarkers for disease and more.

“In developing a first-ever hybrid bioelectronic robot, we are opening the door for a new paradigm of applications for health care innovation, such as in-situ biopsies and analysis, minimum invasive surgery or even cancer detection within the human body,” Li concludes.

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