Your input signal would have a particular frequency and power. As long as both of these are within the specifications of your amplifier, the output signal is just an amplified (sometimes inverted) version of the input.
If the frequency of your input signal is not too high, you can just amplify it to be greater than, say 0.7 V, and use it directly with some digital ICs or rectifiers.
You might want to take a look at power amplifiers (PAs), but your post just mentions sensors and I think a PA is not necessary.