Improved piezoelectricity of porous cellulose material via flexible polarization-initiate bridge for self-powered sensor.

Self-powered piezoelectric sensors based on cellulose nanocrystal (CNC) porous materials are light-weight and portable, whereas using unmodified CNCs can hardly obtain enough piezoelectric properties without external strong polarization due to its irreversible deformation caused by low toughness. Here, we bonded rod-like CNCs with a soft polymer, poly ethylene glycol (PEG), and hypothesized that PEG could toughen the material and its dielectric signal could induce the CNC polarization. We further adsorbed graphene (GR) as surface electrodes to prepare a CNC-PEG-GR piezoelectric porous material with density of 0.096 g·cm−3. The voltage output reached maximum when the frequency matched the dielectric relaxation frequency of PEG. We also increased the length-diameter ratio of porous material pores from 1.1 to 3.3 by adjusting its freeze-drying process, and the voltage output could reach to 0.7 V at a moderate ratio. They could be conveniently integrated into portable self-powered sensors applied to the intelligent wearable electronic devices. Here, we have prepared a flexible piezoelectric cellulose nanocrystals-based porous material using flexible poly ethylene glycol as the piezoelectric activator. The voltage output of the porous material reached the maximum when the compression frequency approached the relaxation frequency of PEG molecules. Then, we optimized the appropriate orientation cells length-diameter ratio of 1.41 by adjustable freeze-dry process and further to make a portable self-powered sensor. [Display omitted] [ABSTRACT FROM AUTHOR]