| 摘要 |
<p>The invention provides an electric potential sensor, comprising at least one detection electrode (12) arranged for capacitive coupling with a sample under test and for generating a measurement signal, and a sensor amplifier (14) adapted to receive the measurement signal as input and to supply an amplified detection signal as output. Input impedance enhancing (34) means provide a high input impedance to the sensor amplifier for increasing the sensitivity of the electrode to reduced electric potentials, and feedback means (46, 52, 54, 56; 56, 61) apply a coherent feedback signal to the input of the sensor amplifier for enhancing the signal to noise ratio of the sensor.</p> |
