Patterned 3D-printed hydrogel as a novel soilless substrate for plant cultivation

Plant roots need water, micronutrients, and oxygen to maintain cellular metabolism and tissue growth, yet traditional hydroponic systems often lack sufficient oxygen delivery. While 3D printing artificial substrates has been explored to mimic the physical structure of soil, it remains unclear which design parameters are critical for supporting full plant development. Here, we present a synthetic, soilless substrate based on 3D-printed hydrogels incorporating triply periodic minimal surface (TPMS) patterns to create internal air-filled channels. These channels remain in contact with the atmosphere, enabling passive gas exchange throughout the substrate. We tested five TPMS geometries (Lidinoid, Split-P, Schwarz-D, Schwarz-P, and Schoen), each with an identical hydrogel volume but with different surface-to-volume ratios. Arabidopsis thaliana seeds germinated directly on the substrates and were monitored for vegetative and reproductive growth over five weeks. Among the designs, the Lidinoid substrate consistently led to the highest number and size of leaves and the earliest and most complete flowering, outperforming both hydroponics and unpatterned hydrogel controls. Our results indicate that the surface-to-volume ratio is a key parameter influencing substrate performance, likely due to its impact on oxygen availability at the root interface. Plants grown on substrates with higher surface areas transitioned to flowering more reliably and rapidly, with flowering efficiency showing a strong positive correlation with surface area. These findings suggest that vascular-like internal architectures can overcome the oxygen limitations of traditional hydroponic systems without requiring active aeration. This work supports the use of additive manufacturing as a powerful tool for engineering soil analogues tailored for indoor agriculture. By combining passive aeration with hydration and nutrient delivery, patterned hydrogels offer a promising, scalable solution for sustainable soilless plant cultivation.