Intestinal Villi‐Inspired Living Biobatteries via Habitat‐Engineered Conductive Hydrogel Architectures

ABSTRACT

Microbial bioelectrocatalysis demands more than electron‐conducting surfaces—it demands living microenvironments that hydrate, protect, and nourish whole‐cell biocatalysts. This biological imperative remains unaddressed by conventional electrode design. Here, we fundamentally reframe microbial biobattery architecture through living habitat engineering, drawing inspiration from the human small intestine—a biological interface evolutionarily optimized to sustain dense, metabolically active microbial communities through high‐surface‐area villi, mucus‐mediated hydration, and short‐path nutrient exchange. We translate these principles into spore‐programmed conductive hydrogel pillar arrays, in which dormant Bacillus subtilis endospores are embedded within poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate)–poly(vinyl alcohol)/reduced graphene oxide hydrogel villi that simultaneously serve as microbial reservoirs, bioelectrochemical scaffolds, and electron‐harvesting conduits. Upon nutrient contact, spores germinate on demand into electroactive cells. This villi topology delivers an 8.3‐fold volumetric power density enhancement (8.04 to 66.45 µW cm ^{− 3} ) over planar controls under volume‐matched conditions. A 24‐device geometry matrix uncovers a coupled radius–height design rule, with peak single‐villus power of 8.35 µW at optimal dimensions. Conformable villi patches demonstrate nutrient‐triggered electricity generation in a simulated pipe environment using a wastewater‐mimicking nutrient/electrolyte solution, while a separate self‐powered array achieves spatially resolved bioelectrochemical sensing. This work establishes living habitat engineering as a transformative paradigm for activatable, architecture‐programmed, and potentially shelf‐stable microbial biobatteries.