Advances in energy harvesting using low profile piezoelectric transducers Shashank Priya Received: 31 May 2006 / Accepted: 8 September 2006 / Published online: 14 March 2007 © Springer Science + Business Media, LLC 2007 Abstract The reduction in size and power consumption of sensors and CMOS circuitry has led to research on on-board power sources that can replace batteries. Batteries require constant charging, while distributed networks need centralized energy sources. In remote applications, battery charging or replacement is difficult and expensive. Therefore, on-site generators that convert available energy into electricity are developed. Piezoelectric energy harvesting is a prime method for converting mechanical energy into electricity. This review covers recent developments in piezoelectric energy harvesting using low profile transducers and presents results from various prototypes. It also discusses the selection of piezoelectric materials for on and off resonance applications and analyzes analytical models for efficiency and power magnitude. Keywords Piezoelectric · Energy harvesting · Macro fiber composite · PVDF · PZT · Transducer · Bimorph · Windmill Introduction Energy recovery from unused power has been discussed. Unused power exists in various forms, including industrial machines, human activity, vehicles, structures, and environment sources. Periodic vibrations from rotating machinery or engines are promising energy sources. Table 1 lists available energy sources. The selection of energy harvesters depends on cost-effectiveness and reliability. Recent approaches include solar, thermoelectric, electromagnetic, piezoelectric, and capacitive schemes. This review focuses on piezoelectric schemes for power harvesting in electronic devices. A brief discussion on the first category is provided in the last section. Table 2 lists the daily average power consumption for a wearable device with three functions: music player, personal organizer, and GSM communication, for three user profiles. Table 3 provides the power requirements for various household electronic devices. These power levels can be continuously harvested from human and industrial activity. A large network with several sensor nodes and data acquisition components requires a centralized energy source. In remote applications, recharging, battery replacement, or wiring can be tedious and expensive. Sensor nodes should be as small as possible to be conveniently placed and used, which limits their lifetime. A device with a 1 cm³ non-rechargeable lithium battery would last 333 days if it consumes 100 μW of power on average. A lifetime of approximately 1 year is not practical. There are four possible ways to realize a distributed sensor network: (1) enhance the energy density of storage systems, (2) reduce the power consumption of the sensor, (3) develop self-powered sensors by generating or harvesting energy, or (4) transmit power from a centralized source to the sensor. The most efficient and practical method is to develop self-powered sensors by harvesting energy from wastedAdvances in energy harvesting using low profile piezoelectric transducers Shashank Priya Received: 31 May 2006 / Accepted: 8 September 2006 / Published online: 14 March 2007 © Springer Science + Business Media, LLC 2007 Abstract The reduction in size and power consumption of sensors and CMOS circuitry has led to research on on-board power sources that can replace batteries. Batteries require constant charging, while distributed networks need centralized energy sources. In remote applications, battery charging or replacement is difficult and expensive. Therefore, on-site generators that convert available energy into electricity are developed. Piezoelectric energy harvesting is a prime method for converting mechanical energy into electricity. This review covers recent developments in piezoelectric energy harvesting using low profile transducers and presents results from various prototypes. It also discusses the selection of piezoelectric materials for on and off resonance applications and analyzes analytical models for efficiency and power magnitude. Keywords Piezoelectric · Energy harvesting · Macro fiber composite · PVDF · PZT · Transducer · Bimorph · Windmill Introduction Energy recovery from unused power has been discussed. Unused power exists in various forms, including industrial machines, human activity, vehicles, structures, and environment sources. Periodic vibrations from rotating machinery or engines are promising energy sources. Table 1 lists available energy sources. The selection of energy harvesters depends on cost-effectiveness and reliability. Recent approaches include solar, thermoelectric, electromagnetic, piezoelectric, and capacitive schemes. This review focuses on piezoelectric schemes for power harvesting in electronic devices. A brief discussion on the first category is provided in the last section. Table 2 lists the daily average power consumption for a wearable device with three functions: music player, personal organizer, and GSM communication, for three user profiles. Table 3 provides the power requirements for various household electronic devices. These power levels can be continuously harvested from human and industrial activity. A large network with several sensor nodes and data acquisition components requires a centralized energy source. In remote applications, recharging, battery replacement, or wiring can be tedious and expensive. Sensor nodes should be as small as possible to be conveniently placed and used, which limits their lifetime. A device with a 1 cm³ non-rechargeable lithium battery would last 333 days if it consumes 100 μW of power on average. A lifetime of approximately 1 year is not practical. There are four possible ways to realize a distributed sensor network: (1) enhance the energy density of storage systems, (2) reduce the power consumption of the sensor, (3) develop self-powered sensors by generating or harvesting energy, or (4) transmit power from a centralized source to the sensor. The most efficient and practical method is to develop self-powered sensors by harvesting energy from wasted