I have successfully designed and implemented AD5933-based impedance measurement system (according to the CN-0217). It works fine in measurement range 100 Ohms - 500 KOhms, which is just fine for me.
Now I would like to perform some bioimpedance measurements and for that, 4-electrodes configuration is requested.
I have no previous experience with VCCS design and I hope that someone can help me. Probably, the most suggested circuit is Howland's... I need help how to meet requirement that maximum extrication current is bellow 800uA (due to the safety reasons).