1. Department of Electrical and Computer Engineering, University of Minnesota, Kenneth H. Keller Hall, 200 Union St. SE, Minneapolis,Minnesota55455, United States
2. College of Science and Engineering Characterization Facility, University of Minnesota, 100 Union Street SE, Minneapolis, Minnesota55455, United States
3. Department of Chemical Engineering and Material Science, University of Minnesota, 421 Washington Ave. SE, Minneapolis, Minnesota55455, United States