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From 2012.igem.org

Week 1 (May 1-4)

This week we went to Biosafety and WHMIS training, where we learned safety procedures and protocols that will be useful when we get to the lab.

Contents 1 Week 2 (May 7-11) 2 Week 3 (May 14-18) 3 Week 4 (May 21-25) 4 Week 5 (May 28-June 1)

Week 2 (May 7-11)

We read some papers about the potentiostat we will be using for the biosensor, and began designing a circuit to take a triangular wave form from 0 to 5 V, amplify it, and offset it to get a waveform from -2 V to 2 V. A large portion of this week was also spent learning how to use MATLAB and LabVIEW software platforms for data acquisition and analysis.

Week 3 (May 14-18)

The circuit design was finalized this week, and we began implementing it on the breadboard. Upon testing the circuit, we found that it was not giving us the predicted results. After a day of troubleshooting, we determined that the Operational Amplifiers were fried and needed to be replaced. Once the circuit was operational, we began using a DAQ to generate an input waveform and measure an output. We wrote a LabVIEW vi for generating a triangular waveform, but had trouble writing software for the measurement. We are currently getting a 'onboard memory overload' error whenever we try to generate output and take back input at the same time.

Week 4 (May 21-25)

This week we found the bugs in our software that were giving us an error whenever we ran simultaneous signal generation and measurement with the DAQ. By slowing the sampling rate (for both input and output), and giving a longer buffer period for the data to be transferred, we were able to get the vi to work entirely. We tested our circuit and the potentiostat using screen printed carbon electrodes in a solution of PbS. This yielded a noisy graph vaguely resembling a voltammogram. The noise was filtered with a digital filter, and gave us a much more readable voltammogram. Next, we tested the potentiostat after adding Chlorophenol Red (in 200 uL increments) to the PbS solution. Based on the small peaks that emerged, we are able to detect CPR electrochemically with our potentiostat!

Week 5 (May 28-June 1)

This week we focused on moving the breadboarded circuit to a prototyping board for ease of use and increased portability. Having little soldering experience, the first board was more of a 'test run', and indeed we ran into several problems, including a short circuit that caused one of the 9V batteries to overheat. The majority of the week was spent refining our technique as well as mapping out a new and improved circuit diagram to ensure success on our next attempt. This involved moving the power supplies to a common ground rather then hooking the batteries up in series away from the board. Another improvement was the quality of user-friendliness. An example of this was to use different colored wiring for the power, ground, and internal wiring on the board. This made navigation much simpler. An improvement that we look forward to next week would be the addition of two hardware filters, as well as higher quality op-amps. We would also like to implement all of this into a fully functional prototype available for field testing, complete with switches, pre-cut holes for usb cords, and easier to use battery compartments.