High-dielectric porous CaCu3Ti4O12/reduced graphene oxide/polydimethylsiloxane foam for wearable, breathable and low crosstalk capacitive pressure sensor

High-dielectric porous CaCu3Ti4O12 (CCTO)/reduced graphene oxide (rGO)/polydimethylsiloxane (PDMS) foam is prepared through a simple sacrificial salt-templating method. By introducing CCTO and rGO fillers into the porous PDMS scaffold, a three-dimensional porous CCTO/rGO/PDMS foam with large dielectric constant of 107.8 is obtained. The CCTO/rGO/PDMS foam also has a low Young's modulus of 0.007 MPa as well as a high water vapor transmission (WVT) rate of 14 mg/cm2·h (0.5 mm thickness). A wearable, breathable and low crosstalk capacitive pressure sensor based on CCTO/rGO/PDMS foam and porous Ag nanowires (NW)/thermoplastic polyurethane (TPU) electrodes has been fabricated. The sensor displays fast response speed (<48 ms), excellent sensitivity (3.5 kPa−1), superior cyclic repeatability and stability (11,000 cycles), as well as high gas permeability (WVT rate of 13 mg/cm2·h). The sensor can be attached to different body positions to monitor diverse physiological activities including breathing, vocal cord vibration and finger touch pressure. Moreover, the pressure sensor array integrated by multiple sensor units with low crosstalk is fabricated to detect spatial pressure distribution.