Intro to Impedance Spectroscopy

[Rajan Kumar]

I am trying to run impedance analysis of molecular imprinting polymers (MIP) made from a neurotransmitter called dopamine.

 

We would like to use dopamine as the polymer matrix to sense concentrations of a specific analyte that is imprinted in the dopamine MIP. We believe that as changing concentrations of the analyte binded to the film will cause a change in the impedance properties.

Since I am only an undergraduate and my PI isn't really electrochemist, I was hoping to gain some advice on how should I approach this.

My initial experiments:

I have followed current papers that utilize EIS for developing immunosensors. So far I haven't gotten any noticeable nqyuist plots for different electrolytes of potassium ferricyanide or sodium chloride.

We are using a Princeton Applied Research Potentiostat.

Pt as the counter electrode

Ag/AgCl (NaCl saturade)

Working electrodes:

Gold coated Quartz Microbalance Crystals (9 Mhz ) or Screen Printed Electrodes with a carbon working electrode (Area of 0.0707 cm^2)

Tried various electrolyte solutions of 0.01 and 0.1 M of NaCl

Here are my recent results:

In the image provided, I got a partial Nyquist plot for the control but I got a straight line for the impedance study of a 60 nm film on the working electrode. I believe it either means that the film has been removed just from multiple use but then I should see something similar to the control with no film.

Your time and opinions would be most appreciated,

Rajan Kumar