Fig. 3: CFI as interface in flexible system.

a Schematic view of CFI working as an electrical interface with the skin in an electrocardiogram (ECG) monitoring system. RA, LA, RR, and LL indicate the CFI electrode placement on the human body. b the ECG signal obtained by CFI during lying down, standing, or walking. c s schematic view of the CFI working as an electrical interface with the conformable sensor. d SEM image of conformable strain sensor on synthetic leather; e CFI-interfaced sensor at different amplitude. f CFI-interfaced sensors at different frequencies of 5% strain; g CFI can protect the sensor from pressure and artificial sweat. h sensing principle of crack-based strain sensor. i FEM simulation of stress distribution in crack-based sensor with and without complex mesh coverage, j Sensing performance comparison between the CFI-interfaced sensor and electrical interconnections without CFI.