Research Projects

Biophotonics Imaging Laboratory

Stephen A. Boppart, M.D., Ph.D.
Assistant Professor
University of Illinois at Urbana-Champaign
Department of Electrical and Computer Engineering and Bioengineering
Resident Physician
College of Medicine
http://nb.beckman.uiuc.edu/biophotonics/

Optical Coherence Tomography (OCT) is an emerging state-of-the-art imaging modality capable of providing micron-scale images of subsurface biological tissue. The OCT technology has proven to be viable over the span of the last decade by imaging tissue cross-sections at depths exceeding 2 cm in transparent tissues (including images of the eye and frog embryo) and 2-3 mm in highly scattering (non-transparent) tissues, such as the skin. In addition, the recent development of an OCT needle fitted with fiber-optics have allowed much deeper penetration of solid tissue masses, such as breast tissue. The advantages to OCT are numerous; the portability, high resolution, low cost and non-invasive nature of OCT make it an extremely attractive technology.

REAL-TIME FUNCTIONAL OCT IMAGING:

LONGITUDINAL TRACKING OF NERVE FASCICLES:

The high-resolution, real-time imaging capabilities of OCT are ideally suited for guiding surgical procedures and interventions. The OCT beam can be delivered through a single optical fiber, making the beam delivery instrument compact, such as a hand-held probe or a surgical biopsy needle. The ability of OCT to image sub-surface structures enables one to identify vessels or nerves and avoid these during surgical incisions. Shown above, OCT can image individual fascicles within a nerve, which is useful during neurosurgical repairs.

Lab Projects

OPTICAL SOURCE DEVELOPMENT
A primary limitation for the widespread and clinical use of OCT is the optical source. An ideal optical source for OCT emits light in the near-infrared region (800-1500 nm), has broad optical bandwidth (75-300 nm) with a near-Gaussian shaped spectrum, is compact, portable, and offers high fiber-coupled output power (>30 mW). Solid-state mode-locked lasers provide both the bandwidth and power, but are large and difficult to operate and maintain. Compact superluminescent diodes are portable, but provide insufficient output power and bandwidth for cellular imaging. A central project of our laboratory is the collaborative development of novel optical sources for OCT. Current possibilities include microstructured or tapered supercontinuum-generating optical fibers, high-power superluminescent diodes, and rare-earth-doped optical fibers.

INTEGRATED OCT AND MULTI-PHOTON MICROSCOPY FOR ANALYZING MICROFLUIDIC BIOMEM DEVICES:

Microfluidic bioMEM devices are becoming increasingly complex with 3-D microstructures and dynamic functional performance. OCT is ideally suited for investigating both the structure and function of these systems. Using high-speed optical Doppler OCT, it is possible to investigate the fluid-flow velocity profiles within these systems to improve the mixing and fluid-handling performance. OCT and multi-photon microscopy utilize the same laser source. Multi-photon microscopy is being integrated with OCT to detect fluorescing molecular beacons within microfluidic devices. Molecular beacons will be used to detect small concentrations of RNA, DNA, or bacteria within environmental or medical samples.

OPTICAL CONTRAST AGENTS FOR OPTICAL COHERENCE TOMOGRAPHY:

Contrast agents are used to enhance the diagnostic capabilities of imaging techniques. Unlike ultrasound, CT, MRI, and microscopy, no contrast agents have been developed for OCT. Our group, in collaboration with Prof. Ken Suslick in the Department of Chemistry, is actively developing novel contrast agents for OCT. Microspheres generated using high-frequency, high-energy ultrasound are used to encapsulate air or particles that exhibit high optical scattering properties. By site-specifically localizing these agents, we are able to enhance the local contrast. Contrast agents such as these can be targeted to specific tissues, such as tumors, and enhance the optical signal detected by OCT.

To Learn more about the Biophotonics Imaging Laboratory you can go to their website at: http://nb.beckman.uiuc.edu/biophotonics/