Another thought is some sort of voltmeter circuit - I need it to be high impedance though - just like a multimeter - so it doesn't interfere with the readings.
The voltmeter would need a 0-5V scale (since the most the sensor can go is 5V and gnd when short cct.
I don't really want to bring a negative supply into the equation, so I think I need a rail-to-rail opamp one that can go right close to ground (the measurements we are interested in will be in the range of 0.7 ? to around 3V when cold. I was reading that Op Amps don't typically output that close (though rail-to rail does?)
And I need it to do that with 5V input and single supply (5V and GND).
TLV2231 ? Bad choice?