SHF: Small: Circuit Support for Maintaining the Continuous-power Abstraction in Energy Harvesting Systems

Technical advances in the design of small, low-power computing hardware alongside rapidly expanding network capacity are driving an explosion of ubiquitous, connected Internet-of-Things (IoT) devices. IoT systems have the potential to transform environmental, transportation, and healthcare industries. Unfortunately, batteries limit the potential societal impact of IoT devices due to their size, weight, cost, maintenance requirement, and flammability. Without shedding batteries from IoT systems, high-density, million device, “deploy-and-forget” deployments made possible by ultra-small computing devices will never happen. Despite a decade of research on replacing batteries with energy harvesting, energy harvesting systems are not capable of being deployed in society. The core deployment challenge is the programmer: harvested energy is scarce and unpredictable, forcing batteryless systems to operate intermittently as power is available despite dramatically changing power conditions and common-case power failures. The human mind cannot reason accurately about such complexity. Making the dream of high-density, million device, “deploy-and-forget” energy harvesting device deployments possible requires hardware support that restores the abstraction of a continuously powered device to programmers, alleviating them of such complex reasoning. The work in this project restores the continuous power paradigm developers are trained for through transparent, low-level hardware mechanisms. Restoring the continuous power abstraction enables deployable and performant batteryless system design, opening the door for transformative industrial- and society-level ubiquitous computing and smart dust systems. The project aims to answer three questions: What modifications can one make to the energy harvesting and management hardware to provide a continuous-power environment for software? What opportunities exist when one decouples hardware operation from power-related software interruptions? What benefits exist when one allows software to inform hardware of its energy needs? The project bridges the gap between constant-power and batteryless systems through: an energy-aware harvester architecture that dynamically responds to changes in power supply and demand to efficiently supply a consistent power level for computation; hardware support for sustaining system and peripheral functionality across power cycles without software intervention; and a hybrid design that tunes the hardware to software’s needs, maximizing responsiveness while minimizing wasted energy. The team introduces hands-on, batteryless system development projects for both undergraduate and graduate students in Computer Science, Computer Engineering, and Electrical Engineering. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.