A supramolecular hygrometer: a novel strategy to grow ordered supramolecular fibers out of amphiphilic donor–acceptor conjugated molecular dyads is exploited by P. Samorì and co‐workers on page 3170 to construct 1D structures. These structures can be integrated as active components in microsized resistive humidity sensors that show unique characteristics, such as response speed and sensitivity, over a wide range of humidity.