Self-Healing Polymer Could Help Create Artificial Muscle For Robotics, Prosthetics
In a major breakthrough of what could be a revolutionary milestone in the field of Robotics and Prosthetics, Materials scientists at Stanford University have developed a super stretchy, self-healing polymer called Fe-Hpdca-PDMS, which can act as a more resilient artificial muscle material.
When stretched to a great length, it has the ability to retract to its original position at room temperature.
While normal elastomers (rubber-like polymers) have the ability to stretch up to two or three times their original length which is great by itself, this newly-developed material can expand to more than 100 times its own length.
What is even more exciting is that this new synthetic material has amazing self-healing properties. When the polymer is cut into half, the elastomer can actually join back, provided that the edges are kept within close proximity. It continues to retain 90 percent of its elasticity and strength.
For instance, if this material is poked with holes, it has the tendency to cover it up on its own. Amazing isn't it?
How this happens you ask? Well, this interesting feat occurs because the iron molecules on one edge of the poked-hole gets attracted to the nitrogen and oxygen molecules on the other edge.
"In our case, the goal was not to make the best artificial muscle, but rather to develop new materials design rules for stretchable and self-healing materials. Artificial muscle is one potential application for our materials." said Zhenan Bao, Materials Scientist at Stanford University, Palo Alto, California.
Getting down to the core of it all, this remarkable material is fundamentally made up of randomly entangled long polymer chains that contain oxygen, carbon, silicon and nitrogen atoms mixed with an iron salt. Chemical bonds are formed between the iron and the nitrogen and oxygen atoms, joining the polymer chains to one another in crosslinks, similar to a fishnet pattern.
The crosslinks allow the polymer chains to move together without sliding away altogether, which in turn enables the material to stretch. When the crosslinks are stretched, broken or rearranged, the material changes its shape accordingly. Once the material is done being messed around, the crosslinks return to their original size and shape.
This material does have its own set of shortcomings though.
In order to use artificial muscles in prosthetics or robotics, they need to respond effectively towards electric fields. However in this case, when an electric field is applied to this newly developed elastomer, it changes in length by just a mere 2 percent as compared to the 40 percent in terms of a biological muscle.
Albeit, there is no denying that the findings by the Stanford University researchers hold immense potential and looks very promising.
The polymer could be worked around with to make artificial muscles, either to replace the missing ones in disabled people or to enable robots to move stuff like how humans do. Further, materials that expand and contract in response to an electric field are often used as pressure or strain sensors in extreme conditions such as in space.
The findings of the discovery have been published in the Nature Chemistry journal.
Photo: DFID - UK Department for International Development | Flickr