# related to change in resistance

Respected sir,

can you design a microcontroller for me which can show us the change in resistance(in giga ohm range) of the sample and which can be linked with phone by the help of a bluetooth

punam:
can you design a microcontroller for me

Do you really mean that?- you want a custom microcontroller?

(And this isn't a design house, it's a forum....)

This Forum is for helping people get their projects working. We don’t design things for you - you must do most of the work.

If you want someone to write a program for you please ask in the Gigs and Collaborations section of the Forum and be prepared to pay.

…R

punam:
can you design a microcontroller for me which can show us the change in resistance(in giga ohm range)

Also that is a very difficult thing to do, what is the application here that requires the measurement of such high resistances?

GOhm - wow. Wondering indeed what that could possibly be.

Wondering how to approach measuring such resistances. Maybe create a voltage divider with another resistor in the same order of magnitude, and then connect the mid point to a high impedance OpAmp (one that has input impedance in the TOhm region - so pA currents). Would require shielded wiring. This approach comes from how a pH probe is read, which is also a probe with output impedance in the GOhm order of magnitude.

Hi,
This can be a very dangerous exercise and a calibration and stability nightmare.

If measuring 10GOhms they use 1000Vdc, and thats the minimum test voltage for that range I have seen, most are 10,000Vdc.

1000 / 10,000,000,000 = 0.000000001A == 0.001uA = 1pA. 1nA (Thanks @wvmarle)
1000 / 10,000,000,000 = 0.0000001 = 0.1uA (I got to get more sleep! ! !)

The meters have special probes and lockout features, and costs a fortune.

Can you please tell us your electronics, programming, Arduino, hardware experience?

Thanks.. Tom..

That should be 1 nA (10-9), not 1 pA (10-12).

wvmarle:
That should be 1 nA (10-9), not 1 pA (10-12).

Thanks, brainfade, gotta get some sleep.
Goodnight mate…

What's a few orders of magnitude here or there. Not going to see that on my meter anyway, even if I could keep those frisky kV at bay.

TomGeorge:
1000 / 10,000,000,000 = 0.000000001A == 0.001uA = 1pA. 1nA (Thanks @wvmarle)

wilfredmedlin:
What's a few orders of magnitude here or there.

Indeed. It was actually four orders of magnitude off Too many zeros there. Hard to count that high.

Anyway, just goes to show how hard it is to measure those resistances and still waiting for OP to come back and tell more about their project.

His biggest issue will, I think, be to keep all that voltitude in the right place and not vaporise him if it decides he's a nice path home.