AnsweredAssumed Answered

What are the measurement limitations of the ADuCM350 in a 3-electrode amperometry/potentiostat application?

Question asked by Murdock on Mar 14, 2017
Latest reply on Mar 1, 2018 by emf

My application is biochemical 3-electrode amperometry with a potentiostat. I am trying to evaluate whether or not the ADuCM350 is a viable approach for the potentiostat instrument or whether we have to roll our own. From the data sheet and user's manual it is hard to determine the limitations of the ADuCM350. How does it compare with the Texas Instrument LMP91000 Potentiostat AFE (analog front end) chip? (The TI LMP91000 appears to be limited to its internal 2.5V reference or a maximum external 5.0V reference as far as the maximum reference voltage it can apply across the VE and CE electrodes and is limited with the transimpedance amplifier feedback resistor (Rtia) values from 2.75k to 350k ohm giving it a current measurement range of 750uA with Rtia = 2.75k down to 5uA with Rtia = 350k (assuming the 2.5V reference).  The TI LMP91000 AFE appears to have been optimized for a slightly different target application and cannot measure the lower current range of interest.)  What is the maximum reference voltage the ADuCM350 can put across the WE and CE electrodes? What is the maximum transimpedance amplifier feedback resistor (Rtia) value -- the data sheet and user's manual are silent on viable values and physical layout making me think that they are not expecting Rtia values in the 1M, 5M, 10M, 20M, or 50M ohm range? What is the smallest current range the ADuCM350 is capable of measuring full scale -- <1nA, 1nA, 10nA, 100nA, 0.1uA, 1uA, or >1uA?