An apparatus for use in a downhole tool is provided. The apparatus includes a membrane configured to isolate an internal environment of the downhole tool from one or more further environments, internal and/or external to the downhole tool; and an electrical element configured to conduct an electrical current. The electrical element is positioned with respect to the membrane such that energy generated by the electrical current passing through the electrical element is incident on the membrane. The membrane is configured to be weakened and/or ruptured when the energy is incident thereon to allow fluid communication between the internal environment and the further environment.