A system for monitoring a charge-based physiological parameter within an internal organ of a living body, and a sensor adapted to be implanted in the living body and an organ therein. The sensor includes sensing elements adapted to sense the charge-based physiological parameter within the organ, and the sensing elements include at least first and second sensing elements that are electrically conductive, aligned, spaced apart and exposed at the exterior of the sensor. The sensor further includes a device for passing an alternating current from the first to the second sensing elements through an ionic solution contacting the sensing elements. The sensor also includes a device for generating a signal corresponding to the impedance of the ionic solution based on the alternating current.
