A 3D-Printed Biomimetic Porous Cellulose-Based Artificial Seed with Photonic Cellulose Nanocrystals for Colorimetric Humidity Sensing

Distributed sensing of environmental parameters is going towards solutions that are more efficient by taking inspiration from flying plant seeds. Yet, present technologies mostly rely on electronics, and they are often heavy and not biodegradable. Here, we develop a biodegradable and porous material, based on cellulose acetate and lignin, and characterize its degree of porosity. We use this material to 3D print lightweight and porous artificial fliers inspired by Ailanthus altissima seeds. By 3D printing, we can tailor in a precise way the morphology of the artificial flier that strongly influences its aerodynamic behavior. We add a cellulose-based photonic crystal for humidity sensing of topsoil by optical readout. These artificial flyers are biomimetic, lightweight and biodegradable and have the same mass (~22.4 mg) and descent speed (~0.64 m/s) of the natural seeds, thus constituting a novel approach for perspective distributed monitoring of relevant environmental parameters (i.e., humidity).