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Glycine, the simplest amino acid, is considered a promising functional biomaterial owing to its excellent biocompatibility and strong out-of-plane piezoelectricity. Practical applications require glycine films to be manufactured with their strong piezoelectric polar 〈001〉 direction aligned with the film thickness. Based on the recently-developed solidification approach of a polyvinyl alcohol (PVA) and glycine aqueous solution, in this work, we demonstrate that the crystal orientation of the as-synthesized film is determined by the orientation of glycine crystal nuclei. By controlling the local nucleation kinetics via surface curvature tuning, we shifted the nucleation site from the edge to the middle of the liquid film, and thereby aligned the 〈001〉 direction vertically. As a result, the PVA–glycine–PVA sandwich film exhibits the highest aver-age piezoelectric coefficient d 33 of 6.13 ± 1.13 pC N −1 . This work demonstrates a promising kinetic approach to achieve crystallization and property control in a scalable biocrystal manufacturing process. 

Cellulose-based materials have gained increasing attention for the development of low cost, eco-friendly technologies, and more recently, as functional materials in triboelectric nanogenerators (TENGs). However, the low output performance of cellulose-based TENGs severely restricts their versatility and employment in emerging smart building and smart city applications. Here, we report a high output performance of a commercial cellulosic material-based energy harvesting floor (CEHF). Benefiting from the significant difference in the triboelectric properties between weighing and nitrocellulose papers, high surface roughness achieved by a newly developed mechanical exfoliation method, and large overall contact area via a multilayered device structure, the CEHF (25 cm × 15 cm × 1.2 cm) exhibits excellent output performance with a maximum output voltage, current, and power peak values of 360 V, 250 μA, and 5 mW, respectively. It can be directly installed or integrated with regular flooring products to effectively convert human body movements into electricity and shows good durability and stability. Moreover, a wireless transmission sensing system that can produce a 1:1 footstep-to-signal (transmitted and received) ratio is instantaneously powered by a TENG based entirely on cellulosic materials for the first time. This work provides a feasible and effective way to utilize commercial cellulosic materials to construct self-powered wireless transmission systems for real-time sensing applications.