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Dr. Aaron Hawkins
Semiconductor Devices and Microfabrication
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Biooptofluidics

Optofluidics has emerged as one of the most rapidly developing areas in the optics field. We are concentrating on optofluidic waveguides in our research, which are structures capable of optical confinement and transmission through fluid-filled cores. These optofluidic waveguides use anti-resonant reflecting optical waveguide (ARROW) layers, which allow for light guiding in a very low refractive index material like water, which normally wouldn't be able to guide light.

Our group is working together with the Great Basin Corporation along with the Applied Optics lab at the University of California, Santa Cruz to develop a chip that uses both optofluidic hollow-core waveguides as well as solid-core waveguides (Figure 1) to form a lab-on-a-chip sensor capable of running single particle analysis on a picoliter-sized sample of blood. Our end goal is to be able to detect the presence of potentially deadly Enterobacter bacteria. These pathogens can show high rates of antibiotic resistance and have high mortality rates. The longer an infected patient goes without the correct antibiotic, the less likely it is for them to survive. Also, the administration of the incorrect type of antibiotic can result in drug-resistant strains. Current methods to detect and analyze this bacteria from a sample of blood involve a lengthy process of in-lab bacterial culturing, which can take anywhere from 18-24 hours before getting results. Our end goal is to be able to achieve these results in 1 hour using a chip that combines liquid-core and solid-core optical waveguides. Our chip has already been proven to detect single nucleic acids in clinical samples.

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Photo by ECEn Department

Figure 2 shows a typical ARROW-based chip we have developed in our own cleanroom using traditional cleanroom techniques. A liquid sample is introduced to one of the fluid reservoirs on the chip (Figure 3) and begins to travel through the hollow-core waveguide. An optical fiber containing a single mode fiber is coupled to the solid-core waveguide, providing an optical excitation volume at the intersection of the solid and hollow-core waveguides (Figure 4).

CAS7.JPG
Photo by ECEn Department

Once the sample reaches this point, target molecules that have been tagged with a fluorescent mixture in a previous step are excited and release light. This signal travels through another solid-core waveguide (Figure 5) to off-chip detectors which analyze the signal. A sample of the signal that was received during some of our tests can be seen in Figure 6. After processing this signal to get rid of unwanted noise, the final signal can be seen in Figure 7. Funding for this project has been provided by NSF and NIH.

CAS 5.JPG
Photo by ECEn Department
CAS 3.JPG
Photo by ECEn Department

Publications

  1. "Optimization of Interface Transmission Between Integrated Solid Core and Optofluidic Waveguides", Yue Zhao, Kaelyn D. Leake, Philip Measor, Micah H. Jenkins, Jared Keeley, Holger Schmidt, and Aaron R. Hawkins, Photonics Technology Letters 24, 46-48, (2012).
  2. "Tailorable integrated optofluidic filters for biomolicular detection", Philip Measor, Brian S. Phillips, Aiqing Chen, Aaron R. Hawkins and Holger Schmidt, Lab in a Chip 11, 899-904, (2011).
  3. "Optimization of Interface Transmission Between Integrated Solid Core and Optofluidic Waveguides", Yue Zhao, Kaelyn D. Leake, Philip Measor, Micah H. Jenkins, Jared Keeley, Holger Schmidt, and Aaron R. Hawkins, Photonics Technology Letters 24, 46-48, (2012).
  4. "Improving solid to hollow core transmission for integrated ARROW waveguides", Evan J. Lunt, Philip Measor, Brian S. Phillips, Sergei Kuhn, Holger Chmidt, and Aaron R. Hawkins, Optics Express 16, 20981-20986, (2008).
  5. "Optofluidic waveguides: I. Concepts and implementations", Holger Schmidt and Aaron R. Hawkins Journal of Microfluidics and Nanofluidics 4, 3-16, (2008).
  6. "Optofluidic waveguides: II. Fabrication and structures", Aaron R. Hawkins and Holger Schmidt Journal of Microfluidics and Nanofluidics 4, 17-32, (2008).
  7. " Planar optofluidic chip for single particle detection, manipulation, and analysis", Dongliang Yin, Evan Lunt, Mikhail I. Rudenko, David W. Deamer, Aaron R. Hawkins, and Holger Schmidt, Lab on a Chip. 7 1171-1175, (2007).
  8. "Advances in integrated hollow waveguides for on-chip sensors", Aaron R. Hawkins, Evan J. Lunt, Matthew R. Holmes, Brian S. Phillips, Dongliang Yin, Mikhail Rudenko, Bin Wu, and Holger Schmidt, Proceedings of the SPIE 6462, 6462OU, (2007).
  9. "Planar single molecule sensors based on hollow-core ARROW waveguides", Dongliang Yin, John P. Barber, Evan Lunt, Dmitri Ermolenko, Harry Noller, Aaron R. Hawkins, Holger Schmidt, Proceedings of the SPIE 6125, 172-184, (2006).
  10. "High-efficiency fluorescence detection in picoliter volume liquid-core waveguides", Dongliang Yin, Holger Schmidt, John, P. Barber, and Aaron R. Hawkins, Applied Physics Letters 87, 211111, (2005).
  11. "Integrated optical waveguides with liquid cores", D. Yin, J.P. Barber, A.R. Hawkins, D.W. Deamer, and H. Schmidt, Applied Physics Letters, 85, p. 3477, 2004.
  12. "Integrated ARROW waveguides with hollow cores", D. Yin, H. Schmidt, J.P. Barber, and A.R. Hawkins, Optics Express, 12 (12), 2710-2715, 2004.