ABSTRACT As society seeks alternatives to energy‐intensive manufacturing, biological growth offers an underexplored route for material fabrication. While prior studies have demonstrated direct ink writing of mycelium‐based composites, these approaches often use mycelium only as a structural filler. Here, we exploit active hyphal growth as a post‐printing, growth‐driven functionalization mechanism to self‐assemble particles and tune material properties. When micro‐ and nano‐particles are introduced into the liquid growth medium, their incorporation follows distinct, size‐dependent pathways. Nanoparticles adsorb onto and armor the hyphae, whilst micron‐sized particles become physically entangled within the growing network. By printing inoculated, cross‐linkable hydrogels via direct ink writing, we spatially confine the mycelial architecture without disrupting growth. We introduce selective particle deposition using a dissolvable gelatin mask, enabling localized functionalization. We explore how the shape morphology evolves as the mycelium grows from the hydrogel scaffold into the media. Incorporation of conductive carbon particles enhances the native bioelectric signaling, increasing the signal‐to‐noise ratio by 2.7‐fold and peak amplitude by 9‐fold. Together, these findings establish a growth‐programmable living fabricating strategy, where multifunctional materials can self‐assemble through the natural expansion of living networks.
Schyck et al. (Tue,) studied this question.