Here, a strategy to overcome the stiff and brittle nature of cellulose-derived carbon nanofibrils (CCNFs) is proposed through a facile, low-cost, and scalable approach. Flexible and conformal CCNFs with a low bending rigidity below 55.4 mN and tunable conductivities of 0.14-45.5 S m-1 are developed by introducing silanol as a multieffect additive in the electrospun hybrid nanofibrous network and subsequent carbonization at a relatively high temperature (900 °C) and chemical vapor deposition of polypyrrole (PPy) on the hybrid carbon nanofibril surface. Silica acts as a lubricant in each rigid carbon fiber to improve flexibility of the CCNF structure as well as a template during cellulose carbonization to prevent the melting of carbon nanofibrils. Meanwhile, the uniform coating of PPy leads to an improvement in electrical conductivity while conserving the porous structure and compressibility of the CCNF nets. These conductive hybrid CCNF films are evaluated as mechanoreceptors and physiological sensors, which are demonstrated to be applied in intelligent electronics including electronic skin, human-machine interfaces, and epidermic electrodes. The design or working principles of the hybrid CCNFs for achieving optimum applicable effects when applied in different scenarios are revealed.
Keywords: conductive; electrophysiology; flexible; pressure sensor; softness.