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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