AC current driven open-bridge configuration for measuring impedance variations of a sensor

According to the invention, there is provided an AC current driven open-bridge configuration for measuring impedance variations of a sensor. The AC current driven open-bridge configuration comprises a first half bridge comprising the sensor being connected to a voltage reference node and to a first AC current source providing an excitation current for driving the first half bridge, a second half bridge comprising a reference impedance being connected to the voltage reference node and to a second AC current source providing the excitation current for driving the second half bridge, a first voltage node at a junction of the first AC current source and the sensor, and a second voltage node at a junction of the second AC current source and the reference impedance. The peak to peak value of an output voltage between the first and second voltage nodes is proportional to the excitation current and the impedance variation in the sensor, when the reference impedance is equal to a base impedance of the sensor and the excitation currents provided by the first and second AC current sources are identical.