Graduate Students Michael Frank and Steven Naleway were interviewed for "Meet the Engineers of Tomorrow"
Graduate Student Steven Naleway is awarded the 2015 Graduate Student Association Graduate Student Peer Mentorship Award
Graduate Student Michael Frank is awarded the Katie Osterday Best Poster Award at the 2015 UCSD Jacobs School of Engineering Research Expo
Graduate Student Steven Naleway is awarded 2015 Abe Hurlich Award from the San Diego Chapter of ASM International
Marc Meyers 2014 MSEA Journal Prize Winner, to receive prize at TMS 2015 conference in Orlando, FL, USA.
Four Presentation and three Poster abstracts accepted to TMS 2015 international conference in Orlando, FL, USA.
To better serve patient healing and comfort needs resorbable bone implant materials have been actively researched and developed for various orthopedic applications. The majority of these bone graft materials are either granular or porous ceramic scaffolds which provide good osteoconductivity and biocompatibility but often lack the necessary mechanical strength. With these requirements in mind, we present a new metal/ceramic complex composite consisting of Magnesium (Mg)-infiltrated hydroxyapatite (HA) scaffolds. The HA scaffolds are fabricated through freeze casting allowing for advanced control of the porosity. Pressureless melt infiltration of Mg metal is then applied to these HA scaffolds in order to form a strong and biodegradable two phase interpenetrating composite. We propose this Mg-HA composite material as a novel material for resorbable bone implant applications that combines high mechanical strength with strong osteoconductivity and biocompatibility.
Woodpeckers avoid brain injury while they peck at trees up to 20 times/s, despite undergoing decelerations up to 1200g. This is due to having a small brain with smooth tissue, strong neck muscles, and an impact-absorption system consisting of the head, beak, tongue and hyoid bone. The tongue is connected to the hypoid bone, which consists of two curved, cylindrical bones. The study of structure and function of the tongue and hyoid bone (hyoid apparatus) has not been reported in detail. The anatomical structure and compositional constituents of the hyoid apparatus was examined to determine its possible role in energy absorption. High-resolution micro-computed tomography and scanning electron microscopy with energy dispersive X-ray spectroscopy was performed. The results show the hyoid apparatus consists of four distinct sections, consisting of cartilage, bone and/or muscles. Additionally, there are four joints between the sections that provide flexibility and a possible energy absorption pathway.
The ostraciidae family (i.e. boxfish) is known for their slow, well controlled swimming motion and complex dermal armor which can be traced back 55 million years. The longevity of this armor alone warrants further investigation; however examination of the carapace reveals a complex and effective protective system consisting of interdigitating scutes (plates). These scutes consist of a layered quadrate collagen base and a ridged mineral face. The interfaces between sctues show a regular triangular suture pattern, however they lack the interpenetrating fibers found in most natural suture patterns (e.g. cranial sutures). Piercing attacks are shielded and the stresses spread by the mineralized ridges of the face, then dissipated in the complex woven collagen base. We present this natural design as biological inspiration and propose protective systems which utilize rigid, stress-spreading plates supported by a woven tough base in order to provide protection against modern assaults.
Ubiquitous throughout nature are two phase ductile-brittle composites (e.g. collagen-hydroxyapatite in bone, aragonite-chitin in abalone shell). This has given rise to a number of techniques to fabricate bioinspired composites consisting of brittle (e.g. ceramic) and ductile (e.g. polymeric, metallic or glassy) phases. A commonly employed technique is freeze casting, where a ceramic scaffold is templated by growing ice crystals, then can be infiltrated with a second phase. While this has shown a great deal of potential, the pores created by freeze casting tend to be small which impedes the infiltration process, especially when dealing with high temperature or high viscosity infiltration. We present a simple method for the creation of enlarged pores during the freeze casting process which eases infiltration. This method employs the chemical tools of hydrophobic hydration and non-stoichiometric solids called clathrate hydrates. We propose this as a new tool to simplify the creation of bioinspired composites.
The alligator gar (A. spatula) is covered with bony scales and an enamel-like surface layer. The scales form a tridimensional pattern in which neighboring scales overlap in such a manner that the thickness conforms and the sum of the overlaps is constant. The mechanical properties and structure are correlated and the tridimensional pattern revealed by computerized tomography is transferred by additive manufacturing to a magnified array of idealized, identical tiles. It is demonstrated that flexibility is maintained while protection is retained. This design is proposed as a model for bioinspired flexible ceramic composite personal armor. Research funded by AFOSR MURI.
Recent work has shown the potential of the freeze casting process as a powerful tool for bioinspired design. However, enhancing the axial strength of these porous ceramic materials through complex manipulation of the colloidal particles is a significant challenge. Magnetic freeze casting provides a potential solution by combining two perpendicular forces: magnetic fields to align particle orientation and ice crystal growth to segregate particle aggregation. This strengthens the porous ceramic along both axes. However, it has previously been limited to specific magnetic solids. We present that, through surface magnetization with charged ferrofluids, colloidal particles with a variety of material properties and morphologies (e.g. sub-micron powders, nanowires and nanotubes) can be magnetically freeze cast. We show that electrostatic interactions between colloidal particles with surface charge opposite to that of the ferrofluids imparts superparamagnetic properties onto every type of colloidal particle tested. Future focus on bone tissue engineering applications will be discussed.
Regular sea urchins (Phylum Echinodermata; Class Echinoidea) use a complex of muscles and calcareous teeth, known as Aristotle’s lantern, to scrape, cut, and chew food and bore holes into rocky substrates along the ocean floor. The calcite crystal orientation of its five teeth has magnesium concentrated (40-45 mol% Mg) in a polycrystalline matrix at the grinding tips of each tooth. A simultaneous incision, when open, protruding outwards, followed by enclosure, when retracting inwards, characterizes the feeding mechanism. A recent bioinspired application, which takes advantage of the cut off and enclose feeding mechanism, is a spring-loaded biopsy harvester that can precisely capture a tumorous tissue sample while safely minimizing the spread of cancerous cells. The morphology and microstructure of Aristotle’s lantern was analyzed with a focus on other possible bioinspired applications.
New Book "Biological Materials Science" by Marc Meyers and Po-Yu Chen