I have used two Ad5933 evaluation boards to collect impedance data from both the arms of human body. I have acquired data in time domain fixing the measurement frequency at 50 kHz.
However, I am not quite sure about the reliability of my data as I getting a repetitive spike pattern (see the figure) in my data. When I am using a single device this did not happed.
What would be the reason for this scenario?
Do you have the same observation when a single AD5933 board is used?
Using a single AD5933 board, you can actually monitor the VOUT and RFB pin to actually see what is happening.
I have tried with single AD5933 evaluation and it gives visible trend without any repetitive spikes. I think the repetitive spikes arise only when both devices are connected to the body and stimulus current of the both the devices would super positioned when acquiring readings. However, I need to eliminate these spikes any sugestions ??
Hi KG Samarawickrama,
Can you provide some information as to the need of using two AD5933 simultaneously or what else do you want to achieve that a single AD5933 can't do? Thanks
Dear isantos ,
The reason for using 2 impedance devices is that I'm monitoring the impedance variation when right arm is occluded for blood flow while keeping the left arm as the control. Therefore, I require 2 devices for impedance measurements.
Have you considered using ADI's latest Bio-Impedance AFE the AD5940? It offers better performance and features over the AD5933. Especially the programmable switch matrix which allows you more flexibility over how you connect electrodes allowing you to measure both arms using a single IC.