The Digital Water Plethysmometer is an instrument designed to provide a useful tool in the measurement of small volume changes. The volume transducer is formed by two Perspex tubes, which are interconnected and filled with a conductive solution.

    The water displacement produced by the immersion of an objet in the measuring tube induces a change in the conductance, as measured between two platinum electrodes in the second tube. The electronic circuit provides great measuring stability and the device has an RS 232 output.