Assembly and Testing of a MEMS Mirror for Endoscopic OCT IMSURE Fellow: Dolly Creger Mentor: William Tang Graduate Student: Jessica Ayers

Definitions Microelectromechanical Systems (MEMS)- micron-scale devices linking mechanical parts to electrical components. Optical Coherence Tomography (OCT)- Imaging technology which uses infrared light to image cross-sections of biological tissue with micron scale resolution. Chemical Vapor Deposition (CVD)- A process in which a controlled chemical reaction produces a thin surface film. Photoresist- A light sensitive coating that is used to transfer the image of a mask onto the surface of a wafer, followed by a reactive ion etch (RIE). Stiction- The surface tension of liquid on MEMS components. Shear Mode Quartz- A piezoelectric effect in a lateral plane.

Realm of Biomedicine Coronary Restenosis Laryngeal cancer, Barrett ’ s Esophagus. OCT for noninvasive techniques for cancer screening. Majority of research lies in linear OCT. Trachea, GI Tract, or blood vessels require a rotary laser beam. 360º rotating devices are currently limited by the size of the motor. Fig 2. coronary artery restenosis Fig 3. Mouse Trachea Fig 1. coronary artery comparison

We are working on a different kind of micromachine…

Simple Micro Machine Fig 4. SEM Image: Dolly Creger

Our Project Develop a smaller 360º rotating mirror that can fit inside a 1 mm diameter probe. This will cut the size of the current rotating devices in half.

Endoscopic Probe Fig 5. Conceptual drawing of endoscopic probe. Jessica Ayers UCI 1 mm

Fabrication Commercial PolyMUMPs Process Silicon Silicon Nitride Poly 0 1 st Oxide Poly 1 2 nd Oxide Poly 2 Metal

L-Edit 592 µm x 527 µm 990 µm x 941 µm

Stiction Fig 4 and 5. Mirror Assembly Jessica Ayers UCI Mirror Assembly

Scratch Drive Fig 6 and 7. Scratch Drive Array Jessica Ayers UCI Electrothermal Actuators Microvibromotors, Electrostatic Micro Conveyer, Dipole Surface Drive Microengine Electrostatic Linear Inchworm Motors Ultrasonic/Magnetic Actuators 520 µm diameter 876 µm diameter

Stepping motion of the SDA: Electrostatic load deflects the plate. Bushing is scratched forward. Voltage is reduced and the plate is pulled forward.

Results Scratch Drive: ~200V Hz Stiction a. Evaporation b. Instantaneous vaporization c. Leave submerged Assembly a. Probe Station b. Microspatula c. Magnetism

Future Work Stiction Continuous laser to vaporize all the liquid instantaneously Backside Etching Shear Mode Quartz Assembly Thicker Ni Coating Photoresist Hinges Fig 8. Absorption of silicon and water, Jessica Ayers UCI

Special Thanks! National Science Foundation UROP-IMSURE Said Shokair Said Shokair Jerry McMillan Jerry McMillanUCI INRF INRF Goran Matejasevic Goran Matejasevic Professor Willliam Tang

Jessica Ayers Charlie Wen Gloria Yang Le "Yanni" Yan