A leak detector includes a leak sensor. The leak sensor includes a bottom ground plane, a porous bottom dielectric substrate arranged on the bottom ground plane, a conductor arranged on the porous bottom substrate, a top dielectric substrate arranged on the conductor, and a top ground plane arranged on the top dielectric substrate. The leak detector also includes readout circuitry electrically coupled to the conductor. The readout circuitry is configured to measure a change in electrical properties in at least the porous bottom dielectric substrate.