| CPC G01N 33/48707 (2013.01) [G01N 27/4146 (2013.01); G01N 27/60 (2013.01); G01R 27/14 (2013.01)] | 23 Claims |

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1. A system comprising:
a sensor configured to generate an impedance greater than 0.5 megaohms (M Ω) when at least some analytes are disposed proximate the sensor; and
circuitry configured to provide an alternating current (AC) voltage to the sensor and sense electrical characteristics of the sensor in response to the AC voltage, the circuitry comprising:
a sense resistor coupled to the sensor;
a first amplifier having a first input, a second input, and an output, with the sense resistor coupled between the second input and the output; and
a second amplifier comprising:
a first input coupled to the output of the first amplifier;
a second input coupled to the first input of the first amplifier; and
an output configured to provide a voltage indicative of the electrical characteristics of the sensor,
wherein the first amplifier is configured to provide the AC voltage to the sensor via the second input.
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