Electrical energy is normally generated from heat, motion, chemical reactions, etc. Piezoelectric materials have the ability to convert a mechanical stress to an electric charge or vice versa. The curie brothers first found this smart property from certain materials in 1880, and since then people have developed various energy storages, sensors and actuators (ex. sonar in world war I). Recently, there have been many efforts to apply the piezoelectric materials in making biomedical devices such as in vivo vibration sensors. The researchers turned to cellulose, the most abundant biopolymer on Earth, because it has shown excellent piezoelectricity and biocompatibility. However, its intrinsic structure-piezoelectricity relationship has not been identified yet. Thus, our research aims elucidating the relationship between cellulose nanocrystals and their piezoelectric properties. We control the polar ordering of cellulose nanocrystals using electric field, and characterize their piezoelectric properties using advanced techniques; piezoelectric force microscopy (PFM) and vibrational sum frequency generation (SFG) spectroscopy. The success of this research will open a variety of high-tech applications of cellulose as piezoelectric materials, especially for biomedical devices.