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.

 

AD5993 Evaluation board recommended setup calibration procedures. data shows sweep 50KHz - 55KHz with impedance varies from 50kΩ - 52KΩ
AN-1053 (Rev. B) (analog.com)

a microfluidic test fixture tap water test for ecoli ect, In a sweep from 1 to 10MHz, The size of the bacteria related to the frequency.
The HF electric field is capable of penetrating the bugs membrane and cytoplasm. It was noticed that
a phase shift was detected at about 7MHz,
Resonance-enhanced microfluidic impedance cytometer for detection of single bacteria - Lab on a Chip (RSC Publishing)

 

AD5993 Evaluation board recommended setup calibration procedures. data shows sweep 50KHz - 55KHz with impedance varies from 50kΩ - 52KΩ
AN-1053 (Rev. B) (analog.com)

a microfluidic test fixture tap water test for ecoli ect, In a sweep from 1 to 10MHz, The size of the bacteria related to the frequency.
The HF electric field is capable of penetrating the bugs membrane and cytoplasm. It was noticed that
a phase shift was detected at about 7MHz,
Resonance-enhanced microfluidic impedance cytometer for detection of single bacteria - Lab on a Chip (RSC Publishing)

Dear Sir, I have to use only the AD 5933 evaluation board. there is no IC/board that can measure impedance up to 10M ohm except AD 5933 and has ability to integrate with arduino, the only problem is frequency calibration, we already have in our lab the impedance analyzer, but it is bulky one, and we don't wanna use it

 

I presented the application note, For some of the relevant information for setting up the board.
I gave some background on possibly what you might be doing. You might need to correct or acknowledge.
Some of those more experienced with measurement logging would then be able to assist.
Please post a photo of your best attempt on the settings to help trouble shoot.

If I am following you correctly the average HF 7 MHz passive twin T notch filter is too extreme for a slight impedance
dip of the ever so small 7 MΩ impedance. We can examine a 7 MHz crystal having an equivalent circuit using parameters for a wafer of quartz.
I would expect that an equivalent circuit for the media of water droplets with small bugs on a glass slide with electrodes
was developed to limit a very finite level of signal. Using a sweep generator might include a precision attenuator.
The compliment to this attenuator would be a low noise amplifier.
We test a radio's receiver front end with a weak signal like this attenuator circuit. The design can be adjusted to compensate the test fixture.
A wide band attenuator from 3 to 8 MHz would then relace the narrow band having flat response over the span.

 

The apparent issue is that the sample IMPEDANCE is not totally RESISTIVE, but also includes either an inductive or a capacitance component. So the resistance calibration only deals with the resistive element.

 

Note that using an analog switch of any sort for switching in a calibration resistance. The issues are both variability and also charge injection. This seems to be another instance where there is no substitute for a mechanical electromagnetic relay.