One of the problems I am trying to solve with the FeAtHEr-Cm platform is to eliminate the instrument bottleneck that we see in analytical chemistry courses. For example, a class of 12 students, even if paired up, will unlikely be able to perform an electrochemistry experiment simultaneously because there are few institutions that would be equipped with a half dozen potentiostats.
That is, unless your institution is equipped with FeAtHEr-Cm potentiostats that your students built.
Each student is using python on their own computer to communicate with the potentiostat they built. In a previous class, we calibrated the feedback resistor in the current-to-voltage converter to ensure that the current reported by the instrument is correct (both students obtained relative errors better than 0.1%).
In this experiment, the students are collecting cyclic voltammograms at scan rates ranging from 1 V/s to 0.01 V/s. This range requires them to change the feedback resistor so that the current range is appropriate for the measurement. They also explore the impact of including a filtering capacitor in the feedback circuit.
Nate is trying a slightly different experiment, using a 10 MOhm feedback resistor, he is determining whether or not the home-built potentiostat can measure nanoamp levels of current. Turns out, we can! Here, the filtering capacitor plays a very important role in the integrity of the voltammogram. The 0.1 uF capacitor used for microamp current ranges is much too large, and when Nate saw that the voltammogram was “too smoothed”, he broke out the Santana lyrics. For everyone’s benefit, we ended class at that point.
Congratulations! A student-made potentiostat capable of using micro-electrode with nA currents!
When I was teaching, we either did a rotation (one group on instrument A, one on instrument B, etc.) OR everybody watch and perhaps run one trial, sharing the instrument. Rotations were more educational to the students but way more demanding – three different, simultaneous exercises were the most I could handle. I wonder how your students will feel – do they complain about not using “real instruments?”
Hard to tell with only two students. One of them is also taking the lab (this is technically the lecture) and he gets to play with the commercial instruments. The other is an environmental science major, and he’s looking forward to the turbidity-meter building as it can apply to his research.