Simulating micro power measuring system.

Hi, I'm trying to simulate in Simulink measuring system for micro power. I need to simulate, how system work depending on measured value, temperature etc. Block diagram of system is below:

I tried implemented it as sigma delta modulator in simulink, but I a little stuck (In attachtment my current simulink model). Could you help me with this implementation? What should be my next step? The sigma delta modulator is correct? Thanks in advance