During week 3, Ellie and I began testing of recently designed glucose sensors. We carried out two tests: cyclic voltammetry (CV) and chronoamperometry. These tests were carried out in various glucose solutions. We designed a serial dilution on a spreadsheet ranging from 0mM to 60 mM, our step size was 6 mM up to 22mM, we then jumped to 10 mM steps. We used dextrose, a synonymous molecule to glucose and PBS solution in order to create our solutions.
Our CV tests allowed us to analyze if we had any current peaks. Surprisingly, many of our samples revealed a linear plot and did not have any peaks. These samples were kept for further analysis but we did not do any chronoamperometry measurements using these samples. Our CV scans were all run for 5 cycles at a scan rate of 200scans/sec.
Our chronoamperometry measurements were set at .15mV, and we then measured current using that constant voltage. We determined the voltage to use by analyzing our CV peaks and at what voltage the peaks were commonly occurring at. The chronoamperometry measurements were each run for 200 seconds. We added a new PBS and glucose solution between each test. We made sure to add the strip simultaneously to the solution as we started the chronoamperometry scan. This stayed consistent for all tests. We also determined that adding the smaller volume of glucose prior to the PBS also helped yield better results. Once we took chronoamperometry measurements for all concentrations for one sample, we were able to look at where each concentration became saturated. The trend that we expected, increased concentration would produce a higher current was seen for most samples. The only discrepancy in this trend was that a lower concentrations (below 14mM) most of our samples did not seem to be sensing the glucose in solution.