Direct 3D Force Mapping Enabled by Flexible Single-Crystal Piezoelectric Sensor Array

The ability to map 3D forces is crucial in tactile sensors. However, most traditional sensors can generally only sense forces in one direction, that is, normal or shear stress. Here, we report a flexible sensor array, which is enabled by combining single-crystal piezoelectric films with different crystal orientations for direct 3D force mapping. Both normal and shear pressure can be quickly and freely distinguished without any crosstalk. This direct 3D sensing feedback has illustrated its high potential application in intelligent robotics, human-computer interaction, medical care, and health monitoring with real-time feedback.