The Internet of Disposable Things (IoDT) has recently emerged as a simple, low-cost, but powerful paradigm for wireless sensor networks. Stand-alone, self-sustaining IoDT devices are essential to providing effective and reliable functioning even in resource-limited environments. A stable power supply is the most critical factor in developing practical IoDT applications because their performance and deployment depend significantly on power availability. In this work, we created a micro-sized (similar to 62 mu L) bacteria-powered biobattery for potentially powering unattended IoDT applications. The biobattery stores solid-phase microbial anodic nutrients and ionic pathways in microliter-scale chambers without an energy-intensive fluidic system, providing a relatively long-term operational capability (>8 days). We revolutionarily converted the liquid anolyte, salt bridge, and cathodic compartment into solid counterparts, increasing their densities and enabling their slow and continuous reactions. Furthermore, the solid-phase components will make the device favorable in miniaturization, integration, and operation with the solid-state IoDT applications. Our micro-biobattery produced a maximum power density of 4 mu W/cm(2) (0.33 mW/cm(3)) and current density 45 mu A/cm(2) (0.37 mA/cm(3)) after 96 h of operation while a liquid-based control device stopped generating power within 4 h.