A Microfabricated Gastrobot for Sustainable On-Water Propulsion

This report presents a ‘Gastrobot’ engineered for extended self-sufficient operation in water bodies. It features microbial fuel cells (MFCs) mimicking a digestive system to convert biochemical into mechanical energy, achieving 135μW/cm power density for autonomous propulsion. The MFCs use hydrophobic/hydrophilic interfaces for nutrient intake and incorporate Bacillus subtilis spores, which germinate in nutrient-rich conditions, fueling the system and enabling motion. A central motor activates for movement, highlighting the robot’s potential as a smart sensor node within an ‘Ocean of Things’ network, advancing global aquatic surveillance and connectivity.

INTRODUCTION

The intersection of robotics and the Internet of Things (IoT) is witnessing transformative innovations inspired by nature’s adaptability and efficiency [1], [2]. Such biomimetic strategies guide the development of robots for environmental monitoring and conservation [3] –[5]. A nascent yet promising innovation in this domain is the "Gastrobot," designed for operation in extreme conditions [6]. Originally, the Gastronome project laid the groundwork by using E. coli bacteria within microbial fuel cells (MFCs) to digest sugar [6]. Despite showing the potential to operate on biomass, it faced challenges in waste management and consistent fuel processing. Post-2001, the Gastrobot’s progress stalled, primarily due to power density constraints that limited practical applications [7]. The successful deployment of Gastrobots depends on a continuous biomass supply for MFCs, conducive growth conditions for bacteria, and effective waste management. However, the complexity of integrating biological processes for energy conversion has posed significant challenges [8] –[10].