Micro scale Energy Harvesting for Batteryless Information Technologies
Continually growing integration levels and miniaturization in electronics has led to the enrichment of features to enable a variety of new applications with simultaneous reduction in system power consumption. The start of the 21st century is hallmarked by the emergence of small information engines (microsystems) as part of "internet of things" thrust to provide the intelligence behind the building blocks of the increasingly automated, digitized, and connected eco system around residential, industrial, health, education, transportation, communication, and other sectors of our civilization. These engines require small amount of power to work in an embedded environment where frequent access for maintenance, and power delivery or battery refurbishment is not desirable. The focus of this chapter is batteryless operation, which is at the center stage of microscale harvesting research efforts to enable such applications. Energy and power budgeting, and system design concerns are reviewed for batteryless operation, and system examples are provided. First part of Sect. 3.1 discusses demand for micro scale information technologies. Section 3.1.3 provides typical power and energy budgets for sensor nodes. The motivations for batteryless operation are examined in Sect. 3.1.4. Power generation is provided as a recent power management thrust in such systems in Sect. 3.1.5. System design issues for realizing batteryless information technologies are covered in Sect. 3.2 with the review of energy harvesting techniques such as small scale solar irradiation, environmental vibration, thermal differences, and ambient radio frequency electromagnetic waves. Finally, the last part of the section briefly discusses upcoming trends and further efforts in enabling batteryless information technologies at a disruptive level.