PURPOSE: To enable the release of the functional material in a composite formed by molding conductive metallic powder, polymerizable monomer or prepolymer and the functional material to a specified shape for a required period of time when needed by connecting a sensor to this composite.

CONSTITUTION: The result of environmental monitoring requiring the release is transmitted as a current or voltage from the sensor 3 to electrodes 2 and is conducted by the metallic powder in the composite 1. The conductive metallic powder is internally moved toward the electrodes 2 by being placed in an electric field at this time. The structure in the composite 1 changes to the structure having many gaps and eventually the diffusion and release of the functional material incorporated into the composite are accelerated. Namely, the conductive composite 1 is formed and the electrodes 2 are mounted thereto. The functional material responding to the electric signal from the sensor 3 is released by utilizing the generation of a change in the internal structure when these electrodes are energized.