Impedance value changes for no reason
I coded my Cyton board to run continuous impedance measurements and connected resistors to check the performance. For a few hours everything run smoothly and the impedance measurements were constant. But suddenly I started getting very high impedance values, more than 50X the original values. Then at some point I got close to zero values and the issue never resolved until I restarted the Cyton again. I've seen this in two different Cyton boards I have.
Do you know what is the reason for that? Why does the measured voltage is so big suddenly? I understand the injected current is 6na so I hope this is constant. Why does the voltage then drops almost to zero.
How can I prevent this? I need to do long measurements and I can't physically reboot the Cyton every time it happens.
Thanks for any help.