Re: [DIYbio] Customize Microelectrode array

What are you trying to find? I don't know if you can measure potential with a setup like that. I'm pretty sure you'd need a complete circuit somewhere. A potential only exists between two points if electrons are being pumped between them. You can't have your reference electrode completely electrically isolated from your culture and get electrons pumped between them. I'm not sure how you could measure electrical potential in a suspension, but my coworker measures the potential generated by biofilms growing on an electrode. Her setup might help point you in the right direction. Here are the description and image of her reactor:

"While bioreactor design has varied greatly throughout the years and between labs, the design of the reactor for microbiological studies has recently converged. Figure1.8A shows a photograph of the most recent generation of electrode bioreactors.The conical chamber holds 15 mL of fluid, contains a stir bar, and is kept at aconstant 30 °C with a circulating water bath. All three electrodes (working, reference and counter) are placed in close proximity in the same chamber. Theworking electrode is a polished graphite flag with a surface area of 3 cm2. The graphite flag is attached to a loop of platinum with a Teflon screw. The counterelectrode is a piece of platinum wire. The reference electrode communicates with the solution across a Vycor frit. Calomel and Ag/AgCl are common referenceelectrodes. These electrodes are connected to a potentiostat. This system allows bacterial respiration to be continuously monitored in the form of electrical current. An example of current production by a wild type G. sulfurreducens biofilm is shown in Figure 1.8B. At any time during growth different electrochemical techniques can be performed on the biofilm, such as cyclic voltammetry (CV). This procedure scans current production at different electrical potentials. The rate at which the working electrode sweeps across different redox potentials can be varied. An example of a cyclic voltamogram is shown in Figure 1.8C."