Archive for bioceramics
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Monday materials mind candy: ‘Printed’ origami ceramic structures
Credit: Bok Yeop Ahn and Jennifer A. Lewis.
As you can see above, ACerS Fellow Jennifer Lewis and her team at the University of Illinois at Urbana-Champaign have figured out how to make intriguing and beautifully simple (yet complex) origami structures by bending and folding planar lattices. The lattices are made by extruding “inks” of ceramic, metal or polymeric materials using a precise, direct-write method.
In general, beads of inks are laid down in a particular pattern and allowed to partially dry. They are then trimmed, folded and finally annealed to complete the structure.
Direct writing of lattice. Credit: Bok Yeop Ahn and Jennifer A. Lewis.
But this makes it sound much too easy. In fact, Lewis, Bok Yeop Ahn, David Dunand and others in her team faced significant materials and technical challenges. In a University press release, Lewis says, “Most of our inks are based on aqueous formulations, so they dry quickly. They become very stiff and can crack when folded.”
She says the challenge, then, was to find a solution that would render the printed sheets pliable enough to manipulate, yet firm enough to retain their shape after folding and annealing. The answer came by combining wet-folding origami techniques (where paper is partially wetted to enhance its foldability) with special inks containing a mixture of fast- and slow-drying solvents.
The combination yields a lattice that can can be partially dry but flexible enough to fold through multiple steps. The origami crane - requiring 15 steps – allows them to demonstrate the agile possibilities of their methods.
For Lewis, a professor of materials science and engineering and the director of the university’s Frederick Seitz Materials Research Laboratory, these structures have a serious side. “By combining these methods, you can rapidly assemble very complex structures that simply cannot be made by conventional fabrication methods,” Lewis says.
Practically speaking, this technique could provide an alternative to existing “rapid prototyping” approaches to build scaffolds for tissue engineering. There are limits to rapid prototyping, which builds 3D structures by laying down layer after layer of material, due to the sagging of lower layers or compressing under their own weight.
Lewis’ team’s method could create light, strong structures that can be bent, folded and rolled out of lattices formed from nearly any pattern. Stents, bone-repair scaffolds, biomedical devices or even catalytic substrates are possible.
Samples of stents and other structures. Credit: Bok Yeop Ahn and Jennifer A. Lewis.
Dunand says the next step is to try larger and much smaller structures and test ink compositions that would contain other ceramic and metallic materials.
“We’ve really just begun to unleash the power of this approach,” Lewis said.
A short video providing a closer look at some of the structures is available here.
Adding . . . Advanced Materials published a paper on this work, and if you look in the comments, the editor of the magazine has kindly posted a link for a free download of the paper.
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Video of the week: Linda Pinckney on glass–ceramic applications
If you have a glass-top stove, you may have wondered why the rest of the glass stays cool when you have only one burner turned on. Linda Pinckney can explain why. Pinckney, an ACerS Fellow, has worked for Corning Inc. for more than 27 years in the field of glass–ceramic materials. Glass–ceramics combine the best of both worlds by carefully controlling the growth of crystals during the reheating of glass (often seeded with nucleating additives). Glass-top stoves are one example. So is Corning Wear and other similar heat resistant nonmetallic cookware. Pinckney also discusses examples of biocompatible and bioactive glass–ceramics.
In the case of stove tops and cookware, researchers and engineers take advantage of the thermomechanical properties of glass–ceramics that provide considerable strength even while be subjected to extremes of very low and very high temperatures.
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Video of the week: Biomedical applications of multifunctional nanomaterial systems
I got a chance to interview Muhammet Toprak at the recent ICACC’10 conference. Toprak is a researcher in the Multifunctional Materials Division of the KTH – Royal Institute of Technology in Stockholm. In this video, Toprak discusses his work as part of a cross-functional team that is working to assemble and test nanoparticle systems for biomedical applications. In particular, they have been working on the synthesis, characterization and in vitro compatability (with immune-competent cells) of tunable superparamagnetic Fe3O4–SiO2 core–shell nanoparticles.
In general, the systems Toprak is working on are similar to those that were discussed in last week’s video regarding drug-delivery systems. Toprak’s materials are conceived as being as being able to deliver a payload, but they are first working on using them to improve imaging of biological tissue sites. For example, he discusses how particles loaded with both magnetic materials (such as iron) and fluorescent dyes could help with imaging a specific tumor, first, before treatment, to plan a surgical approach, and second, during the surgery to indicate if and where residual tumor cells need to be removed.
8 minutes.
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Video of the week - Aldo Boccaccini on the vitrification of hazardous wastes, bioglass and electrophoretic deposition
Aldo Boccaccini is a professor in materials science at Imperial College, U.K. and a member of the London Center for Nanotechnology, a joint project between Imperial College and University College, U.K. In this video, he discusses some of his early work in developing vitrification techniques to render hazardous wastes, such as incinerator residues, inert. He delves into some of his work to develop bioglass materials for tissue engineering scaffolds. Finally, Boccaccini explains some of his pioneering work in the use of electrophoretic deposition for production of nanostructured materials and composites, including composites that contain carbon nanotubes. 13 minutes.
Earlier this year, Boccaccini was named the scientific international adviser to the Ministry of Science, Technology and Innovation of Argentina (his homeland).
For more information about vitrification of hazardous wastes, see this post about DC plasma techniques.
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Video of the week - Del Day on treating cancer with glass microspheres
Del Day, the Curators’ Professor Emeritus of Missouri University of Science and Technology, discusses his work in the field of bioglass. Day, a former president of ACerS, has spent several decades researching bioceramic and bioglass materials, and developing applications for those materials. He is best known for his work in creating glass microspheres that can be used to encapsulate and deliver tiny amounts of radioactive materials. The Mo-Sci Corp., a company Day founded and still leads, manufactures these microspheres. Today, the Cleveland Clinic and other leading medical facilities use Mo-Sci microspheres for the treatment of liver and other cancers. 13 minutes.
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