Toward Sustainable, High-Performance, and Scalable On-Chip Biopower: Microbial Biobatteries with 3D-Printed Stainless Steel Anodes and Spore-Based Biocatalysts

The rapid proliferation of the Internet of Things (IoT) necessitates compact, sustainable, and autonomous energy sources for distributed electronic devices. Microbial fuel cells (MFCs) offer an eco-friendly alternative by converting organic matter into electrical energy using living micro-organisms. However, their integration into microsystems faces significant challenges, including incompatibility with microfabrication, fragile anode materials, low electrical conductivity, and compromised microbial viability. Here, this study introduces a microscale biobattery platform integrating laser powder bed fusion-fabricated 316L stainless steel anodes with resilient, spore-forming Bacillus subtilis biocatalysts. The 3D-printed gyroid scaffolds provide high surface-to-volume ratios, submillimeter porosity, and tunable roughness, enhancing microbial colonization and electron transfer. The stainless steel ensures mechanical robustness, chemical stability, and superior conductivity. Bacillus subtilis spores withstand harsh conditions, enabling prolonged storage and rapid, on-demand activation. The biobattery produces 130 mu W of power, exceeding conventional microscale MFCs, with exceptional reuse stability. A stack of six biobatteries achieves nearly 1 mW, successfully powering a 3.2-inch thin-film transistor liquid crystal display via capacitor-assisted energy buffering, demonstrating practical applicability. This scalable, biologically resilient, and fabrication-compatible solution advances autonomous electronic systems for IoT applications.