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Passivation of Carbon Nanotube Chips for Biosensing Applications. By: Vince Nguyen Faculty Mentor: Dr. Phillip Collins Lab Mentor: Dr. Jaan Mannik. IMSURE PROGRAM. What is Passivation?. According to www.dictionary.com
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Passivation of Carbon Nanotube Chips for Biosensing Applications By: Vince Nguyen Faculty Mentor: Dr. Phillip Collins Lab Mentor: Dr. Jaan Mannik IMSURE PROGRAM
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.
Introduction to Carbon Nanotubes (CNTS) • Extremely small tubes. • A few nanometers wide. • Length >>>>>> Width. • Cylindrical carbon molecules with properties that is potentially useful. • sp2 bonds; stronger than sp3 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/
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 H2(g) sensor using CNTS for patients with breathing problem; they are considering of creating CO2(g) sensor as well.
How do Biomolecules Bind to CNTS www.jcnabity.com/ nanotube.htm pubs.acs.org/cen/topstory/ 7919/7919notw9.html
Experimental Methods Silicon oxide device (clean and uncovered) Silicon oxide device (covered with polymer) Remove of exposed area using mixed solvents Scanning electron microscope (SEM)
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.
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.
Results Device III M = X 2500 ss = 25 t = 2.5 minutes Length = 13.92 microns Width = .64 micron N = 15, t = 4 seconds M = X 2500 ss = 3 n = 1.1 points/micron 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
Continue… Device 2 Device 4 ss = 4, M = X 3000 N = 40, t = 11 seconds Length = 28.67 microns Width = 1.33 microns ss = 1 M = X 3000 n ranges from 1.1 to 1.4 points per micron in length
Verification of Results Before Passivation After Passivation Device I
Continue… Before Passivation After Passivation Device III
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.
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