Patent ID: 7713477

Claim:
A system operable to monitor one or more bio/chemical activities within a first sample relative to a second sample, the system comprising: a first measurement probe and a first reference element coupled to the first measurement probe, the first measurement probe operable to interrogate one or more physical properties of a first sample at a first location of the first sample, and to output, in response, a first measurement signal; a second measurement probe and a second reference element coupled to the second measurement probe, the second measurement probe operable to interrogate one or more physical properties of a second sample at a first location of the second sample, and to output, in response, a second measurement signal; wherein the first measurement probe, the first reference element, the second measurement probe, and the second reference element comprise are coupled together in a bridge circuit configuration, and a comparator coupled to receive the first and second measurement signals, the comparator configured to output a difference signal comprising the difference between the first and second measurement signals, the difference signal corresponding to the difference in one or more bio/chemical activities occurring within the first sample at the first location thereof relative to the second sample at the first location thereof, wherein the comparator includes: a first differential amplifier having a first input coupled to the first measurement probe, a second input coupled to the first reference element, and an output; a second differential amplifier having a first input coupled to the second measurement probe, a second input coupled to the second reference element, and an output; and a third differential amplifier having a first input coupled to the output of the first differential amplifier, a second input coupled to the output of the second differential amplifier, and an output for providing the difference signal.