Crack propagation controlling via sliding cyclodextrin for high-density sensor array

High sensing performance and compact, flexible strain sensor elements are essential for high-density sensor arrays. However, bulk cracks often propagate within the crack-based sensing unit, hindering miniaturization and high-density integration. Herein, we introduce a crack modulation strategy. With this strategy, the layered MXene (Ti 3 C 2 T x ) nanosheets were covalently crosslinked via polyrotaxane. The sliding of movable cyclodextrin molecules along the poly (ethylene glycol) main chain effectively reduce stress concentration and dissipate more energy under stretching, thus inhibiting the extension of cracks and reducing the size of the sensing unit. The strain sensor with a width of 1 mm exhibits high sensitivity (gauge factor of approximately 2527), high stretchability of approximately 40 % strain, low detection limit of 0.001 % strain, and good stability (10 % strain for 1000 cycles). Given this high performance sensing unit and facile fabricating process, a fully printed stretchable sensor array with a device density of 36 sensors per cm 2 is constructed. To confirm the practical applicability of the sensors, we develop a multichannel pulse sensing system for pulse mapping with high spatiotemporal resolution.