Molecular Ferroelectric-Based Flexible Sensors Exhibiting Supersensitivity and Multimodal Capability for Detection

Although excellent dielectric, piezoelectric, and pyroelectric properties matched with or even surpassing those of ferroelectric ceramics have been recently discovered in molecular ferroelectrics, their successful applications in devices are scarce. The fracture proneness of molecular ferroelectrics under mechanical loading precludes their applications as flexible sensors in bulk crystalline form. Here, self-powered flexible mechanical sensors prepared from the facile deposition of molecular ferroelectric [C(NH₂)₃]ClO₄ onto a porous polyurethane (PU) matrix are reported. [C(NH₂)₃]ClO₄-PU is capable of detecting pressure of 3 Pa and strain of 1% that are hardly accessible by the state-of-the-art piezoelectric, triboelectric, and piezoresistive sensors, and presents the ability of sensing multimodal mechanical forces including compression, stretching, bending, shearing, and twisting with high cyclic stability. This scaling analysis corroborated with computational modeling provides detailed insights into the electro-mechanical coupling and establishes rules of engineering design and optimization for the hybrid sponges. Demonstrative applications of the [C(NH₂)₃]ClO₄-PU array suggest potential uses in interactive electronics and robotic systems.