Ultralow-pressure mechanical-motion switching of ferroelectric polarization

Ferroelectric polarization switching, achieved by mechanical forces, enables the storage of stress information in ferroelectrics and holds promise for human interface applications. The prevailing mechanical approach is locally induced flexoelectricity with large strain gradients. However, this approach usually requires huge mechanical forces, which greatly impede device applications. Here, we report an approach of using triboelectric effect to mechanically, reversibly switch ferroelectric polarization across α-In₂Se₃ ferroelectric memristors. Through contact electrification and electrostatic induction effects, triboelectric units are used to sensitively detect mechanical forces and generate electrical voltage pulses to trigger α-In₂Se₃ resistance switching. We realize multilevel resistance states under different mechanical forces, by which a neuromorphic stress system is demonstrated. Notably, we achieve the reversal of α-In₂Se₃ ferroelectric polarization with a record-low mechanical force of ~10 kilopascals and even with tactile touches. Our work provides a fundamental but pragmatic strategy for creating mechanical tactile ferroelectric memory devices.