2/28/2023 0 Comments Gamry echem analystThe RC filter formed by the reference electrode impedance and the reference terminal's input capacitance filters out the high frequency feedback needed for potentiostat stability. With reference electrode impedances greater than 20 kΩ, the potentiostat may oscillate. In all but its fastest control amp speed setting, it is stable on any capacitor in this range - as long as the impedance in the reference electrode lead does not exceed 20 kΩ. Gamry potentiostats have been tested for stability with cell capacitors between 10 pF and 3000 F. Whenever you see sharp breaks in the current recorded on the system, you should suspect oscillation. Typically a potentiostat can be stable on less sensitive current ranges and unstable on more sensitive current ranges. Oscillation often causes excessive noise or sharp DC shifts in the system's graphical output. However, it can affect both AC and DC measurements. Potentiostat oscillation is an AC phenomenon. To make matters worse, almost all electrochemical cells are capacitive because an electrical double layer forms next to a conductor immersed in a solution. The additional phase shift can convert the potentiostat's power amplifier into a power oscillator. The capacitive cell adds phase shift to the potentiostat's feedback signal (which is already phase shifted). Capacitive Cells and StabilityĪll potentiostats can become unstable when connected to capacitive cells. Improving the stability may require trying several different techniques. Potentiostats can become unstable for several reasons. It also has a thermocouple input for temperature measurements.This application note is meant to provide you with several tips and techniques for improving potentiostat stability. It has a number of auxiliary input and outputs designed to help you interface or control ancillary equipment such as a rotating disc electrode. It does well for a variety of applications such as physical electrochemistry (especially at microelectrodes), fast cyclic voltammetry, electrochemical corrosion, electrochemical noise measurements, paints and coatings, and sensors. The Reference 620 is a high-performance, research-grade potentiostat/galvanostat/ZRA designed for fast, low-current measurements.
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