1 electrode array gk-12 meeting november 2 nd 2010 megan easterly
TRANSCRIPT
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Electrode ArrayGK-12 MeetingNovember 2nd 2010
Megan Easterly
Electrochemistry Oxidation
Loss of electrons Electrode removes
electrons from the solution Anodic peak current
Reduction Gain of electrons Electrode gives electrons
to the solution Cathodic peak current
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Electrodes Working (WE)
Where the reaction of interest occurs Current is measured
Reference (RE) Measures WE potential by
maintaining a stable potential Auxillary (AE)
Electron provider/remover Electrolyte
Electrically conductive solution
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Gold Electrode Array
8 Au working 1 Au reference 1 Au auxillary Study FDCA 12
3 4 5 6
78
aux ref
Ferrocenedicarboxylic Acid (FDCA)
E0 ferrocene = +0.361 V vs. NHE
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Bard, A.; Faulkner, L., “Electrochemical Methods. Fundamentals and Applications” 2nd Ed. Wiley, New York. 2001Image courtesy of Dr. Karst research group:http://www.uni-muenster.de/Chemie.ac/karst/research/projects/hyphenated%20techniques.htm
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The Math
Randles-Sevcik equation
€
ip = (2.69 ×105)n3
2ADOv1
2CO*
€
ip = peak current (A)
n = number of electrons transferred per mole (moles)
A = electrode area (cm2)
DO = diffusion coefficient (cm2/sec)
v = scan rate (V/sec)
CO* = concentration (moles/cm3)
Bard, A.; Faulkner, L., “Electrochemical Methods. Fundamentals and Applications” 2nd Ed. Wiley, New York. 2001
Simultaneous Detection
External reference and auxillary
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Simultaneous Detection
Normalized currents to electrode area
Linearity
> 0.9990
Sensitivity (μA*mm-2*mM-1) Ox 1.43 ± 0.07 Red -1.46 ± 0.07
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DPV of FDCA
Optimal potential determination vs. AgAgCl
0.43 V vs. Au
0.37 V
Ran individually
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Amperometry of FDCA
On-chip reference and auxillary 0.37 V
Individual detection
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Amperometry of FDCA
Normalized to electrode area Linearity
> 0.9987 Sensitivity
22.44 ± 12.93
nA*mm-2*mM-1
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New Mask
Well defined areas Working = 0.09 mm2
Reference = 2.25 mm2 Auxillary = 2.25 mm2
Spacing = 0.3 mm
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Future Work
Fabrication of new electrode array Chemiluminescence detection of NO donor Calibration of electrodes using NO Modification of Au array
Nafion Polypyrrole
Diab, N.; Oni, J.; Schulte, A.; Radtke, I.; Blochl, A.; Schuhmann, W., Talanta, 61, 2003, 43-51