Bio-bot breakthrough: Tiny machines with muscle tissue take a walk

Today, robots can be powered by all kinds of energy sources, from solar cells to chemical fuels to rechargeable batteries. What’s next? A generation of machines powered biologically, using muscle cells that expand and contract just as they do in the human anatomy.

These “bio-bots,” less than one centimetre long, can be precisely controlled because their muscle cells move in reaction to an electric field. The bio-bots walk faster or slower in correlation with the rate of the electric pulses signalled by engineers.

Each bio-bot is comprised of a flexible 3D printed hydrogel base, living muscle cells and two posts that serve as legs. Like the muscle-tendon-bone system in the natural world, the hydrogel structures the bio-bot as a backbone, the cells provide the muscular support and the posts act as tendons.

While biological machines have certainly been engineered before, this new group is the most efficient to date. Bio-bots were first made to walk using heart cells from rats, but because of the heart’s autonomous beating, scientists were unable to control the expansion and contraction that powered the movement.

The research team at the University of Illinois at Urbana-Champaign discovered that skeletal muscle cells provide a better alternative, as they allow the engineers to power the bots on and off and control speed by varying the electric current.

Rashid Balir, leader of the bio-bot study, explained further: “Skeletal muscles cells are very attractive because you can pace them using external signals. 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.”

So far, muscle power seems to be a promising technology with a wide range of potential medical and environmental uses.

“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,” said Caroline Cvetkovic, co-first author of the study’s publication.

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To make these applications a reality, engineers will continue to hone their control over the bio-bots, implementing neurons within their structures to enable steering capabilities.

Since 3D printing allows for the speedy production of differently shaped hydrogels, the researchers can easily experiment with various models.

Soon, they hope to create a hydrogel backbone that can change directions as a result of different kinds of signals, further expanding the functionality of these “living” machines.


Charging up: the nanofibre set to boost electric vehicle battery technology

High-powered but inefficient batteries that are typically used to power electric cars could see a dramatic improvement after researchers created a new material to be used in them.

A group of scientists has created a nanofibre that could help batteries store energy in a more efficient way.

By doing so they may be providing a fast track approach to creating more powerful lithium-sulphur batteries, which have been touted as the future.  The technology could lead to electric vehicles that can drive far further before needing to be recharged.

The group, from Ludwig-Maximilians-Universitaet, Germany, and the University of Waterloo, Canada, worked on the material that could help to show the way forward to newer lithium-sulphur batteries.

Lithium-sulphur batteries have a high storage capacity and are cheaper to make than traditional batteries.

However, they have not been used in mainstream products as yet due to the low number of times they can be recharged before they have to be disposed of.

The new material has a structure that gives it a high surface-to-volume ratio. A sugar cube sized piece of the new material has a surface area equal to that of seven tennis courts.

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Benjamin Mandlmeier a co-author on the work said: “The high surface-to-volume ratio, and high pore volume is important because it allows sulfur to bind to the electrode in a finely divided manner, with relatively high loading.

“Together with its easy accessibility, this enhances the efficiency of the electrochemical processes that occur in the course of charge-discharge cycles.

“And the rates of the key reactions at the sulfur electrode-electrolyte interface, which involve both electrons and ions, are highly dependent on the total surface area available.”

One of the other researchers on the work, Thomas Bein, said: “Nanostructured materials have great potential for the efficient conversion and storage of electrical energy.”

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To synthesis the carbon fibers the chemists prepare a template using commercially available fibers.

It was then filled with a mixture of carbon, silicon dioxide and surfactants which is then heated at 900°C.

During this process the carbon nano-tubes and the pore size shink to a lesser extent than they would without the template.

It also leaves the fibers in a more stable state.