A device designed to apply uniaxial pressure to the surface of an electro-active material while simultaneously applying a current to the material under controlled temperature conditions and then measuring the displacement of the material by means of a laser interferometer. The device involves a housing with a chamber in which a sample of material is secured. The chamber has an aperture with a quartz window that allows the laser beam from the interferometer to pass. The sample is connected to electrodes and the chamber is filled with dielectric oil that applies the uniaxial pressure to one side of the sample. The device is placed onto a thermal control system. When the appropriate thermal and pressure conditions are established, current is applied to the sample and the interferometer measures the displacement.