The present invention provides methods of conducting emulsion polymerizations and dispersion resulting therefrom. The dual function circuit can be selected between functioning as a current to voltage conversion circuit connected to a photodiode and as a testing circuit for testing the transimpedance amplifier without exposing light to the photodiode. Next, the method may include receiving information scanned by the computing device and either positively or negatively marking one of the indicia depending on the information scanned by the computing device.