Current limitation and indication

[mr_embedded]

Hi all!
I currently work with electrical muscle stimulation and need some advice on electrical safety and indications.
I will be working with optocouplers with an output of maximum 40 mA, I therefore need an electrical component that indicates if the current is higher than the maximum allowed, as an AD converter but with current instead of voltage. Does anyone have any suggestions for such a component?
The second problem I have is similar but I need to know if the current that passes through a conductor is too small (below a given amount of current). Any suggestions for this application?

Kind regards,
mr_embedded

 

[(*steve*)]

For both cases you could sense the voltage dropped across a resistor through which the current flows. Voltage drop is proportional to current so you would be looking for a voltage between 2 limits. For this you could use a pair of comparators.