EPFL scientists have developed
microscopic, hydrogel-based muscles that can manipulate and mechanically
stimulate biological tissue. These soft, biocompatible robots could be
used for targeted therapy and to help diagnose and prevent disease.
Credit: Nebahat Yenihayat
Human tissues experience a variety of
mechanical stimuli that can affect their ability to carry out their
physiological functions, such as protecting organs from injury. The
controlled application of such stimuli to living tissues in vivo and in
vitro has now proven instrumental to studying the conditions that lead
to disease.
At EPFL, Selman Sakar's research team has developed micromachines
able to mechanically stimulate cells and microtissue. These tools, which
are powered by cell-sized artificial muscles, can carry out complicated
manipulation tasks under physiological conditions on a microscopic
scale.
The tools consist of microactuators and soft robotic devices that are
wirelessly activated by laser beams. They can also incorporate
microfluidic chips, which means they can be used to perform
combinatorial tests that involve high-throughput chemical and mechanical
stimulation of a variety of biological samples. This research has been
published in Lab on a Chip.
Like Legos
The scientists came up with the idea after observing the locomotor
system in action. "We wanted to create a modular system powered by the
contraction of distributed actuators and the deformation of compliant
mechanisms," says Sakar.
Their system involves assembling various hydrogel components -- as if
they were Lego bricks -- to form a compliant skeleton, and then
creating tendon-like polymer connections between the skeleton and the
microactuators. By combining the bricks and actuators in different ways,
scientists can create an array of complicated micromachines.
"Our soft actuators contract rapidly and efficiently when activated
by near-infrared light. When the entire nanoscale actuator network
contracts, it tugs on the surrounding device components and powers the
machinery," says Berna Ozkale, the study's lead author.
With this method, scientists are able to remotely activate multiple
microactuators at specified locations -- a dexterous approach that
produces exceptional results. The microactuators complete each
contraction-relaxation cycle in milliseconds with large strain.
In addition to its utility in fundamental research, this technology
offers practical applications as well. For instance, doctors could use
these devices as tiny medical implants to mechanically stimulate tissue
or to actuate mechanisms for the on-demand delivery of biological
agents.
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