Concentration and scan rate dependent electrochemical measurements using a floating electrode

Kühlkamp, Wouter and Leemeijer, Bram (2015) Concentration and scan rate dependent electrochemical measurements using a floating electrode.

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Abstract:Nanogap devices have a narrow channel of 65 nm height with electrodes on both sides. These devices have such small volumes that they can be used to detect single molecules using electrical signals. One possible new way of doing this, could be to leave one electrode floating while sweeping the other electrode and looking at the charge that is built up on the floating electrode. In this report the in fluence of the concentration of 1,1-ferrocenedimethanol that is inside a nanogap device and the scan rate on the charge that is built up on the floating electrode is researched. Furthermore the infl uence of measuring equipment and the lifespan of the nano fluidic device are investigated. The expectation for the concentration dependency is that a lower concentration of molecules would cause the floating electrode to follow the applied potential less, since there are fewer molecules that can transfer charge. For the scan rate dependency the expectation is that a slower scan rate would cause the floating electrode to follow the applied potential better, since a slower scan rate means that the floating electrode has more time to catch up with the electrode that is being swept. The experimental results are that for the concentration dependency the expectation is correct for con centrations of 1 μM 1,1-ferrocenedimethanol and higher, but for concentration lower than 1 μM it doesn't work, concluding that the limit of this technique at room temperature is somewhere between 100 nM and 1 μM. A simulation is done and confirms that the limit lies around the mentioned point. Looking at the scan rate the expectation is correct, with lower scan rates more charge builds up on the floating electrode for the same concentration. The measurement equipment employed infl uences the results significantly. Combined with the short lifespan of the devices, this renders the results not fully reproducible.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:53 electrotechnology
Programme:Chemical Engineering MSc (60437)
Link to this item:http://purl.utwente.nl/essays/68163
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