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RESEARCH

 

Background

 

Miniaturized devices have had a significant impact on our society in revolutionizing the electronics industry. A similar trend of size-reduction is emerging in the health care industry to produce small bioanalytical devices for disease diagnosis, novel methods for drug delivery to treat diseases, and microfabricated platforms for studying microorganisms. Nanostructured materials, in particular, offer tremendous opportunities for engineering advanced device components for diagnostic and therapeutic applications. Despite the recent research on these materials, significant challenges remain in controlling material properties, interfacing nanocomponents with instrumentation, and engineering their interaction with biological systems.

 

The overarching objective of our group is to utilize our expertise at the intersection of nanostructured materials development, microfluidics, and device engineering to overcome challenges in the evolution of miniaturized devices relevant to microelectronics and life sciences. The projects listed below are a selected group of our current research thrusts. Please contact Prof. Erkin Şeker for more information.

 

Current Projects

 

Nanoporous Metal Synthesis and Characterization

Nanoporous metals, with their highly-tunable properties, are promising candidates for multi-functional device coatings1. In order to develop application-specific nanoporous metals, it is imperative to have a thorough understanding of material properties at multiple levels, including electrical, thermo-mechanical, and interfacial. Previously, we engineered micro-beam arrays to probe thermo-mechanical properties2-5, studied wetting in nanoporous thin films6, and synthesized highly-flexible conductive composites7.

 

Currently, we are working to create a library of application-specific nanoporous metals, high-throughput characterization tools to study key material properties, and a framework that captures the link between materials properties, mechanical properties, and nanofluidic transport.

 

Freestanding nanoporous gold beam array

 

 

Engineering Tissue-Material Interaction

Tissue response is due in part to a complex set of material properties, including elasticity, surface chemistry, and surface microstructure. A widely accepted hypothesis is that the right combination of material properties (such as mechanical, electrochemical, and elemental) specific to a biomedical device will increase device efficacy and safety. A critical step in understanding tissue response is to identify the correlation between material properties, biomolecule-surface interactions8,9, and biological responses10.

 

Currently, we are combining nanoporous metal technology and microfluidic platforms11,12 to create large-scale material-tissue interrogation arrays. These microfabricated platforms will enable the systematic study of material-biomolecule-tissue interactions and help us in identifying optimal tissue-material combinations that maximize the desired biological response.

 

Astrocyte adhering onto porous surface

 

 

Creating Translational Biomedical Devices

The scarcity of medical devices that can both detect physiological activity and stimulate it impose a significant obstacle to effective therapeutics. This is particularly important in neurological disorders, since neurons exhibit both electrical and chemical activity as a part of their normal function. Previously, we demonstrated that nanoporous gold coatings increase the sensitivity of multiple electrode arrays in detecting neural electrical activity from brain tissue13.

 

Currently, we are applying the recent progress in fundamental science and technology from the earlier thrust areas to create multi-functional neural electrodes that can detect and modulate neural activity. We hope that one day this technology can help in the treatment of neurological disorders such as epilepsy.

Hippocampus slice on multiple electrode array

 

Reference Papers

 

1.     Seker, E., Reed, M.L., Begley, M.R., “Nanoporous gold: fabrication, characterization and applications,” Materials 2:2188 (2009).(Invited Review for Special Issue: Porous Materials; Open Access)

2.     Zhu, J., Seker, E., Bart-Smith, H., Begley, M.R., Reed, M.L., Kelly, R.G., Zangari. G., Lye, W., “Mitigation of tensile failure in released nanoporous metal microstructures via thermal treatment,” Applied Physics Letters 89:133104 (2006).

3.     Seker, E., Gaskins, J.T., Bart-Smith, H., Zhu, J., Reed, M.L., Zangari, G., Kelly, R.G., Begley, M.R., “The effects of annealing prior to dealloying on the mechanical properties of nanoporous gold microbeams,” Acta Materialia 56:324 (2008).

4.     Seker, E., Gaskins, J.T., Bart-Smith, H., Zhu, J., Reed, M.L., Zangari, G., Kelly, R.G., Begley, M.R., “The effects of post-fabrication annealing on the mechanical properties of freestanding nanoporous structures,” Acta Materialia 55:4593 (2007).

5.     Seker, E., Reed, M.L., Begley, M.R., “A thermal method to reduce microscale void formation in blanket nanoporous gold films,” Scripta Materialia 60:435 (2009).

6.     Seker, E., Begley, M.R., Reed, M.L., Utz, M., “Kinetics of capillary wetting in nanoporous films in the presence of surface evaporation,”Applied Physics Letters 92:013128 (2008).

7.     Seker, E., Reed, M.L., Utz, M., Begley, M.R., “Flexible and conductive bilayer membranes of nanoporous gold and silicone: synthesis and characterization,” Applied Physics Letters 92:154101 (2008).

8.     Huang, L., Seker, E., Begley, M.R., Utz, M., Landers, J.P., “Quantitative end-grafting of DNA onto flat and nanoporous gold surfaces,”MicroTAS Proceedings 2:1567, San Diego, CA (2008).

9.     Huang, L., Seker, E., Landers, J.P., Begley, M.R., Utz, M., “The energetics of surface adsorption and molecular interactions for short ds-DNA,” Langmuir 26:11574 (2010).

10.   Seker, E., Berdichevsky, Y., Staley, K.J., Yarmush, M.L., “Microfabrication-compatible nanoporous gold foams as biomaterials for drug delivery” Advanced Healthcare Materials 1:133 (2012). (NIH Public Access)

11.   Leslie, D.C., Easley, C.J., Seker, E., Karlinsey, J.M., Utz, M., Begley, M.R., Landers, J.P., “Frequency-specific flow control in microfluidic circuits with passive elastomer features,” Nature Physics 5:231 (2009).

12.   Seker, E., Leslie, D.C., Haj-Hariri, H., Landers, J.P., Utz, M., Begley, M.R., “Non-linear pressure-flow relationships for passive microfluidic check-valves,” Lab on a Chip 9:2691 (2009).

13.   Seker, E., Berdichevsky, Y., Begley, M.R., Reed, M.L., Staley, K.J., Yarmush, M.L., “Fabrication of low impedance nanoporous gold multiple electrode arrays for neural electrophysiology studies,” Nanotechnology 21:125504 (2010). (NIH Public Access)