In my college days (in the 80s) I worked at a mountaineering store. We sold a lot of Gore-Tex, polypropylene and other “breathable” fabrics designed to keep the elements out and allow the body to ventilate. These fabrics were revolutionary at the time, and this kind of innovation needed to be explained. We described them to customers as “the next best thing to skin,” an “extension of our skin.” We weren’t talking then about materials that performed “better” than skin. Looks like that might be about to change.
Graphene Ushers in a New Class of Membranes
An international team of mechanical engineers reports in ACS Nano that the super-strong material known as graphene is porous in membrane form, and can therefore be made to function as a molecular filtering system. MIT associate professor and co-author Rohit Karnik calls porous graphene “a platform technology for a new class of membranes.” These membranes could one day be used to filter harmful compounds from water, or control drug delivery, says Karnik.
Researchers are already hard at work trying to engineer graphene with pre-determined hole sizes. These experiments are a build on what was essentially an accidental discovery. In the process of strength- and stress-testing graphene, the team discovered tiny holes in the material that heretofore was appreciated for its impenetrable and “self-healing” properties. So far they’ve determined the size of graphene’s intrinsic pores (between 1 and 15 nanometers in diameter), and have proven the material’s ability to filter certain molecules while allowing other specific molecules to pass through. ”In some sense it’s the first step to practically realizing graphene-based membranes,” Karnik says.
I can only imagine the opportunities for application of this technology. Transplants, vascular repair and skin grafts come to mind. It might even be used to disrupt the medical device sector, by allowing machines that deliver substances to minimize and redirect byproduct and excess. We’ll keep an eye on this accidental innovation, and report back with further developments.
Here’s a link to the paper (http://pubs.acs.org/doi/abs/10.1021/nn303869m), along with the abstract:
We report graphene composite membranes with nominal areas more than 25 mm2 fabricated by transfer of a single layer of CVD graphene onto a porous polycarbonate substrate. A combination of pressure-driven and diffusive transport measurements provides evidence of size-selective transport of molecules through the membrane, which is attributed to the low-frequency occurrence of intrinsic 1–15 nm diameter pores in the CVD graphene. Our results present the first step toward the realization of practical membranes that use graphene as the selective material.
Sources used for this post and for further reading:
- Byron Freney, Brand Strategist at Vital Works