1. Passivation of Carbon Nanotube Chips for Biosensing Applications By: Vince Nguyen Faculty Mentor: Dr. Phillip Collins Lab Mentor: Dr. Jaan Mannik IMSURE PROGRAM

2. What is Passivation? According to www.dictionary.com -To treat or coat (a metal) in order to reduce the chemical reactivity of its surface. -To coat (a semiconductor) with an oxide layer to protect against contamination and increase electrical stability. Why Research Passivating CNTS Chips? -Contribute knowledge to understand more about nanoelectronics. -Gain experience in a more technical laboratory work by working with others. -Future contribution to biochemistry, chemistry, and physics.

3. Introduction to Carbon Nanotubes (CNTS) Extremely small tubes. A few nanometers wide. Length >>>>>> Width. Cylindrical carbon molecules with properties that is potentially useful. sp 2 bonds; stronger than sp 3 bonds in diamond. All atoms are on the surface of single-walled nanotubes. www.abb.com/global/ abbzh/abbzh254.nsf/0/1474d... http://www.nano-lab.com/image5.html www.fujixerox.co.jp/.../ inbt/m_electronics/

4. Big Picture of Current Research Minimize the amount of electrochemical reactions to accurately do electrical measurements on CNTS chips. Detect if biomolecules actually bind to CNTS in electrolyte solutions. Current scientific/medical companies successfully create H 2(g) sensor using CNTS for patients with breathing problem; they are considering of creating CO 2(g) sensor as well.

5. How do Biomolecules Bind to CNTS www.jcnabity.com/ nanotube.htm pubs.acs.org/cen/topstory/ 7919/7919notw9.html

6. Why Passivation?

7. Experimental Methods Silicon oxide device (clean and uncovered)Silicon oxide device (covered with polymer) Scanning electron microscope (SEM)Remove of exposed area using mixed solvents

8. SEM’s Contribution to Research Allow successful creations of big windows. Allow verification of big windows to see if they are successfully removed (observation). Work with NORAN System SIX to allow successful creations of line windows. Allow verification of line windows to see if they are successfully removed (observation). Spot size mode in SEM is the command that contribute a lot to line window’s creations.

9. Limitations of Our SEM Higher magnification causes polymer’s exposed area to burn. Scan 1 mode’s scanning box can’t be minimize for smaller window’s creations. Measurement of beam current is quite complex. SEM system does not have a built-in command to automatically scan the area of interest on silicon oxide chips at an exact amount of time that we want. Using SEM to do passivation requires quick and fast hand movement to minimize the amount of exposure of beam current on unwanted area.

10. Results Length = 13.92 microns Width =.64 micron N = 15, t = 4 seconds M = X 2500 ss = 3 n = 1.1 points/micron M = X 2500 ss = 25 t = 2.5 minutes M = Magnification ss = Spotsize AcV = Accelerating Voltage = 10 kV (Constant) N = # of points per scan t = total time per scan WD = working distance = 10 mm (Constant) n = points scan per unit length Device III

11. Continue… Device 2Device 4 n ranges from 1.1 to 1.4 points per micron in length N = 40, t = 11 seconds Length = 28.67 microns Width = 1.33 microns ss = 1 M = X 3000 ss = 4, M = X 3000

12. Verification of Results Before PassivationAfter Passivation Device I

13. Continue… Before PassivationAfter Passivation Device III

14. Future Research May explain why strange dots exist when creating line windows. May create even smaller windows if measured interference is found to be unacceptable.

15. Acknowledgements I would like to thank… My Mentor: Dr. Phillip Collins My Lab Mentor: Dr. Jaan Mannik Researchers in Lab: Brett Goldsmith, Dr. Yuwei Fan, Alex Kane, and Derek Kingrey IM-MURE Program UC Irvine Coordinator: Said Shokair