A potentiostat is an instrument used in chemical and biological tests that controls the voltage between two electrodes, working and reference, at a constant value. Chemical and biological tests are typically run in a three-electrode system, which includes the aforementioned working and reference electrode as well as a counter electrode. These systems are used to test the electrical activity of certain compounds or microbes, where the electrode acts as either the electron acceptor or electron donor. By monitoring the current and plotting the data against either time (chronoamperometry) or potential (voltammetry), information can be obtained as to the electrochemical activity of chemical compounds and/or microbes. In this project, we will present a design for this potentiostat using the ATMega644, an external digital-to-analog converter (DAC), and a series of operational amplifiers (op-amps). We will utilize the serial peripheral interface (SPI) to communicate between the microcontroller and DAC, the op-amps to process the signal from the DAC and apply a potential to the electrochemical cell, and the internal analog-to-digital converter (ADC) to record the current at the working electrode.
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