PhD Dissertation Defense for Hyejun Ra

Hyejun Ra hra at
Mon Aug 25 09:45:25 PDT 2008

University PhD Dissertation Defense


In vivo cellular imaging with MEMS scanners


Hyejun Ra


Department of Electrical Engineering

Stanford University


Research Advisor: Professor O. Solgaard


Date: Wednesday, August 27, 2008

Time: 1:15 PM (Refreshments served at 1 PM)

Location: CIS-X Auditorium, Center for Integrated Systems




The ability to image through tissue with high resolution in vivo enables
non-invasive early cancer detection in humans and therapeutic research in
live pre-clinical animal models. The dual-axes confocal (DAC) microscope
architecture is proposed to miniaturize a tabletop microscope into a
handheld or endoscope-compatible size. I will present the 2-D
(two-dimensional) MEMS scanner that enables in vivo real-time imaging in the
DAC configuration. It consists of a 2-D gimbal structure in double
silicon-on-insulator (SOI) layers and is actuated by electrostatic vertical

In the second part, I will present a handheld DAC microscope system where
the MEMS scanner is aligned and integrated with miniature optics. Deep
tissue imaging with 3-D reconstruction is demonstrated.

Finally, the application of the miniaturized DAC microscope in in vivo
intravital imaging will be shown in therapeutic research of siRNA silencing
in the skin.


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