Search for: All records

Project-based learning is an important tool in undergraduate engineering education, providing opportunities for students to deepen their understanding of engineering fundamentals, to enhance their capacity for problem solving and communication, and to develop specific engineering-related skills. Here, we describe the efforts of a team of undergraduate students in creating a silicone venous valve model and experimental flow control setup, and in demonstrating the basic capabilities of the overall experimental system. We describe the process of designing and building the venous valve models and test setup and lessons learned by the students through this experience. In addition to providing invaluable experience for the students involved, this project has provided a visual demonstration of the function of venous valves, and provides a platform for fundamental research on the effect of venous valve shape, size and mechanical properties on the development of disease such as deep vein thrombosis (DVT) and pulmonary embolism (PE), which are a leading cause of death in the United States, especially among hospital patients. Findings from research using this test setup can move us toward a better understanding of patient risk levels for DVT and PE, so that physicians can make informed decisions regarding preventative measures. 

Melanin is a stable, widely light-absorbing, photoactive, and biocompatible material viable for energy con- version, photocatalysis, and bioelectronic applications. To achieve multifunctional nanostructures, we synthesized melanin nanoparticles of uniform size and controlled chemical composition (dopamelanin and eumelanin) and used them with titanium dioxide to fabricate donor–acceptor bilayers. Their size enhances the surface-to-volume ratio important for any surface-mediated functionality, such as photo- catalysis, sensing, and drug loading and release, while controlling their chemical composition enables to control the film’s functionality and reproducibility. Inkjet printing uniquely allowed us to control the de- posited amount of materials with minimum ink waste suitable for reproducible materials deposition. We studied the photochemical characteristics of the donor–acceptor melanin–TiO2 nanostructured films via photocatalytic degradation of methylene blue dye under selective UV-NIR and Vis-NIR irradiation con- ditions. Under both irradiation conditions, they exhibited photocatalytic characteristics superior to pure melanin and, under UV-NIR irradiation, superior to TiO2 alone; TiO2 is photoactive only under UV irradiation. The enhanced photocatalytic characteristics of the melanin–TiO2 nanostructured bilayer films, particularly when excited by visible light, point to charge separation at the melanin–TiO2 interface as a possible mechanism. We performed ultrafast laser spectroscopy to investigate the photochemical charac- teristics of pure melanin and the melanin–TiO2 constructs and found that their time-resolved photo- excited spectral patterns differ. We performed singular value decomposition analysis to quantitatively deconvolute and compare the dynamics of photochemical processes for melanin and melanin–TiO2 heterostructures. This observation supports electronic interactions, namely, interfacial charge separation at the melanin and TiO2 interface. The excited-state relaxation in melanin–TiO2 increases markedly from 5 ps to 400 ps. The results are remarkable for the future intriguing application of melanin-based con- structs for bioelectronics and energy conversion.