Team:Brown/Project/Testing

Resistance

Resistance

• Team Toxipop started off the summer focusing on Resistance measurements rather than Conductance. Much of our summer work was devoted to the construction of an electrical circuit unique to our purpose. Many additions were made to the apparatus each week. Below, you will find information about the different "versions" of the apparatus including final information about our switch to Conductivity.

Our First Apparatus

• We started off the summer with the goal of constructing a measuring apparatus that would offer provide consistent and reliable resistance readings. We made sure to keep the electrodes stationary and at a fixed distant in each different sample of bacteria. Our very first apparatus was made with Legos and poster board. At this point we only had a standard voltmeter that could detect large resistance changes between different salt solutions. The changes we expected to see, however, were on a much smaller scale.

Our First Apparatus

Revisions to the First Apparatus

• Our first apparatus presented many complications. First and foremost was the sensitivity factor. We calculated the amount of E. coli bacteria cells expected in each sample and the corresponding net ionic content. These values cannot be accurately measured with a standard voltmeter.
• In addition, the electrodes of the first apparatus did not remain stationary and were difficult to manage. They were made of Copper alloy and multi-stranded. The copper was most likely performing redox chemistry. The DNA and other charged particles released from the cells collected on the wires throughout the experiment.

• Our new apparatus utilized a Data Aquistion Card and the LabView Program. Team Toxipop created an electrical circuit within LabView.
• The new apparatus also consisted of a six-well plate, PDMS Mold, and Platinum Wires.

NewApparatus

New Apparatus