Physics & Astronomy

Fibers and Fluidics from High Voltage and Cotton Candy

presented by

Leon M. Bellan, Ph.D.
Postdoctoral Associate
Department of Chemical Engineering
Massachusetts Institute of Technology

Summary:
This talk will discuss the use of fibers on both the nano- and micro-scale for applications in biology, regenerative medicine, sensing, and nanoscale electronics.  Electrospinning, a commonly used technique for forming nanoscale fibers, is the process by which an electrically forced fluid jet produces solid fibers. While this technique is simple to employ, characterization of the process and the resulting fibers is not trivial. The strong flow in the jet can orient and stretch molecules and particles embedded within the jet and resulting fibers. Using techniques such as high speed video tracking of fluorescent particles, polarized Raman spectroscopy, and atomic force microscopy, direct characterization of the electrospinning jet and isolated nanofibers yields insight into the behavior of the jet and the material properties of the resulting fibers. Novel electrospinning system designs allow for improved control over fiber deposition. This controlled deposition can be used to “draw” fiber patterns that may then be used as devices, masks, scaffolds for cells, or sacrificial templates to form nanoscale fluidic structures.

A significant hurdle in regenerative medicine is the lack of techniques to fabricate artificial vascular networks to maintain cell viability within 3D engineered tissue. While nanoscale fluidic structures are useful for molecular analyses, they cannot serve as artificial vascular systems because the channels are too small. However, just as sacrificial nanofibers may be used to form nanofluidic structures, sacrificial microfibers may be used to form microfluidic structures. Sacrificial microfiber networks produced using a standard cotton candy machine can be used to form 3D microfluidic networks that mimic many properties of natural capillary beds. This technique has several advantages, including being inherently three dimensional, inexpensive, and scalable. The 3D microfluidic networks produced using sacrificial microfibers are able to deliver soluble compounds to large volumes due to their high 3D channel density.

Biography:
Dr. Leon M. Bellan received his B.S. in Physics at Caltech in 2003 and his Ph.D. in Applied and Engineering Physics at Cornell in 2008. At Cornell, he studied applications and properties of electrospun nanofibers. His work focused on microstructure and mechanical characterization, electrospinning jet dynamics measurements, and the use of nanofibers for fabrication purposes. His current work in the Langer Lab at MIT builds on the idea of forming nanochannels with sacrificial nanofibers; he is currently developing techniques using sacrificial cotton candy to produce 3D microfluidic networks that may be used as artificial vascular systems in engineered tissue. His research interests currently focus on the development of scalable micro/nanofabrication techniques for the production of smart materials with novel functionality.  His work has been featured on the National Geographic channel, NPR, the Boston Globe, the USA Today, and other major news outlets.