Science Buddies: "Ask an Expert"

Hi there
My son is doing the Microbial fuel cell experiment with the Magical Microbes kit - he has 3 cells and 2 of them are not working after Day 9. The one that is working is ocean mud and it is blinking 32 times every 10 seconds. The garden soil worked for a few minutes and stopped. The biosolids cell has not worked at all.
We have tried squishing out bubbles, we have made sure the mud is wet, it is kept warm, undisturbed, followed all directions carefully including the wiring connections.
We would like to know if we can dump the samples, and try collecting new ones of the same type but still use THE SAME ELECTRODES ? We don't have time to order new electrodes.
Please advise as to what we can do.
Thank you.

Hi - I encourage you to check the information on the "help" tab for the microbial fuel cell project your student is doing. There is a great deal of troubleshooting information there that may help your student assess the current state of the cells. There is a helpful timeline chart there as well that offers some general expectations in terms of times. If you are on day 9, you may still want to wait a few days. Your student should be taking measurements every day, as noted in the project, and that data is important to have.

Help information: https://www.sciencebuddies.org/science- ... l-mud#help

The help information also notes that the electrodes can be reused:

"Q: Is there a way to clean out the microbial fuel cell without damaging it so that I can use it in another experiment?
A: Yes, the microbial fuel cell can be cleaned out without damaging it. To do this, carefully rinse the vessel and electrodes with tap water. The electrodes should be gently rubbed while rinsing them until the water running off of them is not dirty anymore. Also, to make sure you are starting with a clean slate of bacteria for each test, the vessel and electrodes should be quickly rinsed with 70% isopropyl rubbing alcohol, which should kill the bacteria. To do this, you can put the electrodes in the vessel (using it as a cup) and fill it with just enough alcohol to submerge the electrodes. Get some of the rubbing alcohol on the inside sides of the vessel while you do this, too. Then pour off the rubbing alcohol and briefly rinse the electrodes and vessel with tap water (so the rubbing alcohol does not remain on these parts). Make sure to follow all proper safety precautions when using the rubbing alcohol."

I hope this helps.

Amy
Science Buddies