July 2, 2014

Engineers Use Muscle Cells To Create Improved, Controllable Bio-Bots

redOrbit Staff & Wire Reports - Your Universe Online

University of Illinois at Urbana-Champaign engineers have developed a three-dimensionally printed biological robot that is powered by muscle cells and controlled using electrical pulses, according to research published Monday in the online early edition of the journal Proceedings of the National Academy of Science.

In the study, bioengineering professor and lead investigator Rashid Bashir and his colleagues explain how they were able to develop this new generation of advanced “bio-bot” that is powered by a strip of skeletal muscle cells. The fact that those cells can be controlled by electric pulses allows the developers to have unprecedented command over its functions, while also allowing them to customize the machine for a variety of specific applications.

“Biological actuation driven by cells is a fundamental need for any kind of biological machine you want to build,” Bashir explained in a statement. “We’re trying to integrate these principles of engineering with biology in a way that can be used to design and develop biological machines and systems for environmental and medical applications.”

[ Watch the Video: Muscle-Powered Bio-Bots: Soft Biological Machines Take A Step Forward ]

In 2012, Bashir and his associates developed a type of bio-bot that was soft, biocompatible, approximately seven millimeters long and capable of walking by itself. The robot was a non-electronic biological machine that had been forward-engineered by the Illinois team using only hydrogel, heart cells from rodents, and a 3-D printer.

That bio-bot was powered by the heart cells, but since those cells constantly contracted, the engineers could not control the machine’s movement. Since the upgraded version of the bio-bot uses skeletal muscle, it can be easily controlled by the developers, and can also be easily customized using other forward design principles.

“Skeletal muscles cells are very attractive because you can pace them using external signals,” explained Bashir. “For example, you would use skeletal muscle when designing a device that you wanted to start functioning when it senses a chemical or when it received a certain signal. To us, it’s part of a design toolbox. We want to have different options that could be used by engineers to design these things.”

This new design was inspired by the muscle-tendon-bone complex found in nature, the researchers noted. The bio-bot has a 3D printed hydrogen backbone which is strong enough to give the machine structure, yet flexible enough that it can still bend like a joint.

In much the same way that tendons connect muscle to bone, a strip of muscle is attached to the backbone using two posts. The posts also double as the feet for the new robot model, and the speed that the robot travels can be altered by adjusting the frequency of the electric pulses, according to the researchers. The higher the frequency, the faster the muscles contract and the more quickly the bio-bot moves.

“It's only natural that we would start from a bio-mimetic design principle, such as the native organization of the musculoskeletal system, as a jumping-off point,” said co-first author and Illinois graduate student Caroline Cvetkovic. “This work represents an important first step in the development and control of biological machines that can be stimulated, trained, or programmed to do work.”

“It's exciting to think that this system could eventually evolve into a generation of biological machines that could aid in drug delivery, surgical robotics, 'smart' implants, or mobile environmental analyzers, among countless other applications,” she added.

The next step for the engineers is to find a way to gain even more control over the motion of the bio-bots. For instance, they might attempt to integrate neurons so that they can be steered in different directions by using light or chemical gradients. They also hope to use 3D printing to develop a new hydrogel backbone that allows the bio-bot to move in different directions based on different signals.

“The goal of 'building with biology' is not a new one – tissue engineering researchers have been working for many years to reverse engineer native tissue and organs, and this is very promising for medical applications,” said co-first author graduate student Ritu Raman. “But why stop there? We can go beyond this by using the dynamic abilities of cells to self-organize and respond to environmental cues to forward engineer non-natural biological machines and systems.”

“The idea of doing forward engineering with these cell-based structures is very exciting,” added Bashir. “Our goal is for these devices to be used as autonomous sensors. We want it to sense a specific chemical and move towards it, then release agents to neutralize the toxin, for example. Being in control of the actuation is a big step forward toward that goal.”


FOR THE KINDLE: The History of 3D Printing: redOrbit Press