Articles by Ryan R. Hansen in JoVE
Fabricating Reactive Surfaces with Brush-like and Crosslinked Films of Azlactone-Functionalized Block Co-Polymers Mohammadali Masigol1, Niloy Barua1, Bradley S. Lokitz2, Ryan R. Hansen1 1Chemical Engineering Department, Kansas State University, 2Center for Nanophase Materials Sciences, Oak Ridge National Laboratory Surface fabrication methods for patterned deposition of nanometer thick brushes or micron thick, crosslinked films of an azlactone block co-polymer are reported. Critical experimental steps, representative results, and limitations of each method are discussed. These methods are useful for creating functional interfaces with tailored physical features and tunable surface reactivity.
Other articles by Ryan R. Hansen on PubMed
Microstencils to Generate Defined, Multi-species Patterns of Bacteria Biomicrofluidics. Nov, 2015 | Pubmed ID: 26594264 Microbial communities are complex heterogeneous systems that are influenced by physical and chemical interactions with their environment, host, and community members. Techniques that facilitate the quantitative evaluation of how microscale organization influences the morphogenesis of multispecies communities could provide valuable insights into the dynamic behavior and organization of natural communities, the design of synthetic environments for multispecies culture, and the engineering of artificial consortia. In this work, we demonstrate a method for patterning microbes into simple arrangements that allow the quantitative measurement of growth dynamics as a function of their proximity to one another. The method combines parylene-based liftoff techniques with microfluidic delivery to simultaneously pattern multiple bacterial species with high viability using low-cost, customizable methods. Quantitative measurements of bacterial growth for two competing isolates demonstrate that spatial coordination can play a critical role in multispecies growth and structure.
Controlling Condensation and Frost Growth with Chemical Micropatterns Scientific Reports. Jan, 2016 | Pubmed ID: 26796663 In-plane frost growth on chilled hydrophobic surfaces is an inter-droplet phenomenon, where frozen droplets harvest water from neighboring supercooled liquid droplets to grow ice bridges that propagate across the surface in a chain reaction. To date, no surface has been able to passively prevent the in-plane growth of ice bridges across the population of supercooled condensate. Here, we demonstrate that when the separation between adjacent nucleation sites for supercooled condensate is properly controlled with chemical micropatterns prior to freezing, inter-droplet ice bridging can be slowed and even halted entirely. Since the edge-to-edge separation between adjacent supercooled droplets decreases with growth time, deliberately triggering an early freezing event to minimize the size of nascent condensation was also necessary. These findings reveal that inter-droplet frost growth can be passively suppressed by designing surfaces to spatially control nucleation sites and by temporally controlling the onset of freezing events.