NDnano Undergraduate Research Fellowship (NURF) 2013 Project Summary

1) Student name: Elizabeth Huschke 2) Faculty mentor name: Prof. Scott Howard 3) Project title: On-Chip Optical Diagnosis Using Capillary Electrophoresis 4) Briefly describe any new skills you acquired during your summer research: The main phases of my research were fabrication of microfluidic channels, characterization of lipid spectra, and integration of silicon/germanium waveguides with the microfluidic channels. For the channel fabrication, I was trained in photolithography equipment as well as cleanroom safety and gowning procedures. To characterize the lipid spectra I learned how to use a Fourier Transform Infrared Spectroscopy (FTIR) machine and techniques for analyzing the resulting data in MATLAB. For the integration of the channels and waveguides I learned how to use plasma treatment to bond the two materials. 5) Please briefly share a practical application/end use of your research: Optical analysis of the results of electrophoresis separation experiments has many potential applications. Most immediately, Paul Bohn’s lab is looking to use the technology to track lipid biomarkers correlated with oxidative stress, which is often associated with Alzheimer’s disease, Parkinson’s disease, and Amyotrophic Lateral Sclerosis. In the long run, this technology could potentially be used to identify any biological molecules in separation experiments provided that they absorb light in the infrared range. Project summary: Electrophoresis is a common separation method used to identify the components of biological samples. A potential difference is applied to the sample and differences in electrophoretic mobility cause ions to travel at different rates and separate into bands which can be identified through a number of detection techniques. Electrophoresis can also be carried out in microfluidic capillaries, enabling faster separations and smaller sample sizes. Capillary electrophoresis is a common component in microfluidic “lab-on-a-chip” systems. Optical waveguides coupled with microfluidic channels present the possibility of a novel detection scheme for on-chip capillary electrophoresis. Though the propagation of energy is confined to the waveguide through total internal reflection, an exponentially decaying oscillating electric and magnetic field called the evanescent wave extends beyond the waveguide boundaries. Interaction between this evanescent wave and the surrounding medium affects the intensity profile of light within the waveguide. This property can be used to identify dissolved ions in capillary electrophoresis channels.

  My project addressed the early stages of development of a coupled waveguide and microfluidic system to evaluate the effectiveness of evanescent field detection in cerebrospinal fluid separations important for the study of Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis. My main activities involved fabricating the microfluidic channels and testing methods for integrating them with on-chip waveguides. I also worked on characterizing the spectra of the molecules of interest.    

                                                                                                                                Publications (papers/posters/presentations): Poster at 2013 Undergraduate Research Summer Symposium: “On-chip Optical Diagnosis using Capillary Electrophoresis”

3-­‐D  visualization  of  device  design   Sample  microchannel  in  PDMS  bonded  to  silicon  microchip