Hello guys! now, the AD620 instrumentation amplifier chip could not deal well with low voltages below 1 volt as we noted on breadboard, i suppose we may have one of two possible solutions:-
1. we add a summer circuit( http://www.vias.org/feee/opamp_09.html ) prior to the AD620 Instrumentation amplifier to add a DC offset voltage of +1V DC to the incoming small DC signal in order to attain the required threshold for the signal to be amplified, (these modifications( amplification & offset) will be taken into account in the software, to have proper results)
2. we simply use a small non-inverting DC Amplifier based on 741 opamp http://www.radio-electronics.com/info/circuits/opamp_non_inverting/op_amp_non-inverting.php
I shall get back soon on directives of designing the splashboard 2,0 PCB. Thanks.
in the mean time, if you have come across any material on best PCB design practices, you can please share with us here. Any other related resources are welcome too