A method for modulating roughness of a surface, comprising: providing a first pre-stressed electrically conductive layer coupled to a dielectric elastic foundation provided over a second conductive layer ; and subjecting the two conductive layers to a voltage difference, thereby modulating the roughness of the first surface. The clinical thermometer body is of one-piece molded construction and, furthermore, a pliable section having exceptional dustproof and waterproof properties is sleeved over the depressible flat element of its on-off switch. The liner includes a bottom wall and an upstanding side wall. The present invention omits any type of inflatable body requiring the injection of fluids to effectuate expansion of the tissue expander.