Dear Sir,
I hope this message finds you well.
I am using the AD 5933 evaluation board for impedance measurement; The data sheet says it can measure the impedance up to 10M ohm. I am currently measuring the impedance of a microfluidic device, where I capture the bacteria that increase the impedance from 3M ohm to 8M ohm, which is within the range of 10M ohms. I have encountered an issue where, for instance, if the impedance measures 8M ohms and I use a 3M ohm resistor for feedback during calibration, I do not obtain the correct impedance value. However, using an 8M ohm resistor for calibration provides an accurate impedance measurement. So the problem is, every time I have to calibrate the AD 5933 if there are slight variations in the impedance value to get the correct result
I have a few questions:
1) Is it possible to use a single resistor value as a feedback Resistor for calibration to measure impedance ranging from 1 ohm to 10M ohms, thereby overcoming the challenge of frequent calibration? If so, could you please suggest some solutions to address the issue of frequent calibration?
2) I recently read a paper where the author utilized an HMC 245A switch to address the issue of frequent calibration in impedance measurement. Is this method effective? The HMC 245A switch is described as a non-reflective SP3T (Single Pole, Triple Throw) RF switch. In this paper, they used different resistors with an HMC 245A switch and it automatically calibrates AD 5933.
3) Could you recommend a method, switch, or IC that if I combine it with AD 5933 and they automatically calibrate the AD 5933 and I get the correct impedance of my device from 1 ohm to 10M ohms without needing to change the feedback resistor repeatedly?
Your assistance in this matter would be greatly appreciated.
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