Piezoelectric Energy Harvesting

In recent times, there is a feature in the advancement of ultralow energy device integration in micro-electromechanical systems (MEMS) and communications devices and electronics through wireless network sensors. For devices, battery powers are often required, a medium that often limits the performance of these devices due to the batteries' low life span.

Also, the emergence of piezoelectric energy harvesting is due to the advancement of power electronics and extensive research across energy harvesting. Energy harvesting as an alternative to natural energy can be described as the course of acquiring an infinitesimal volume of energy from raw and natural energy for accumulation and storage and subsequent usage. Most cases, energy harvesting devices are converted and transformed from ambient energy into the forms of electrical energy because it develops an independent energy system.

This is essentially done via replacing batteries and minimizing related sustenance expenditure and also repairing power reserve cables. The energy harvested is reproduced from solar energy, thermal, kinetic, and wind energies as well as salinity gradients. However, piezoelectric energy poses a challenge sometimes because of the brittle nature of a few properties it enhanced.

Although solar energy can function in large viscosity outdoors, it presents a challenge in capturing and incorporating it for indoor use. Thus, mechanical energy is an alternative to the piezoelectric energy harvesting medium that has been explored for use in the sensor network modules.

To target and harvest energy from the environment, sensor networks consisting of wireless networks in vehicles, buildings, even the human body in the form of measuring humidity, temperature, sound, and pressure, etc are used to provide data that are gathered through the gateway sensor nodes. Sensor nodes consist of the antenna of a radio, a microcontroller, and electronic circuits for interface with its sensors as well as a reliable energy source.

These wireless sensor nodes then perform their functions in distributing and collecting data for independent energy use in the areas of industrial automation, health and clinical departments, agricultural activities, military and civil services, etcetera.

The use of piezoelectric energy harvesting provides an alternative to the limits dependency on batteries which has limited lifespan poses. A restriction that has proved as a critical component to impeding the longevity of wireless sensor nodes in different industries. The energy harvesting process hence involves using the atmosphere of the energy from the environment of sensor devices and converting them into serviceable electrical energy.

Unlike batteries thus, energy harvesting presents the potential of a limitless channel of energy by powering wireless sensor devices and electrical devices as a whole including mobile phones.

To achieve a perfect level of energy harvesting, piezoelectric materials can be used because of their rare and peculiar ability to convert mechanical energy into a serviceable and usable electrical energy. The devices are in the form of nanogenerators which is a sustainably new technology with an extreme amount of reliable energy to power wireless devices.

More so, unlike micro-electromechanical system generators, nanogenerators improved the energy vacuum with its flexible power sources feature which is useful for implantable biomedical detectors. Hence, the piezoelectric effect converts mechanical power to create alternatives for batteries in wearable electronic device sensors and other wireless networks across industries, sectors, and government offices and buildings.

Properties for Piezoelectric Energy Harvesting

There are materials for this conversion process and they include ceramics, polymers, composite materials, single crystals, and MEMS generator systems, the nanogenerator systems are of importance too.

Piezoelectric is a word that originates from the Greek word “piezo” and the word “electric” which means pressure and electricity respectively. This means that with the fundamental application of force into piezoelectric materials, an electric charge is incurred across the material and this is regarded as the direct effect of the piezoelectric.

Contrariwise, when the application of such electric surge affects the material, it results in a mechanical deformation which is known as the indirect effect of the piezoelectric. However, in energy harvesting, the direct effect is exploited. A lot of piezoelectric materials have been developed over the years but amongst the most commonly used are perovskite lead zirconate titanate, a polycrystalline monolithic ceramic recognized as PZT often doped with lanthanum which constructs hard piezoelectric while niobium constructs soft piezoelectric.

Piezoceramics have universal use in sensors and actuators via direct chain enabling operation without concern on voltages. Other materials include lead-zirconate, lead-titanate, and barium-titanate although the most used piezoceramic is the PZT because of its extremely high electromechanical coupling ability. Although the PZT is a very brittle ceramic which makes it fragile to holding strains and damages.

Piezoelectric MEMS Generator System: to harvest energy from vibration, through a beam, a mass is upheld and a piezoelectric coating is placed above it. As the mass vibrates, the piezoelectric level is mechanically destroyed and defaced which makes the required voltage generated.

Additionally, the cantilever structures are essential energy harvesting systems with high-level stress intake on the piezoelectric material which minimizes the dimensions of the devices.

The Piezoelectric Nanogenerator System

Zhong L. Wang in the Georgia Institute of Technology had a Nano Research Group with influences in converting nanoscale mechanical energy into serviceable electrical energy through the applications of nanogenerator. With their research, an increment in the production of nanogenerators as a more efficient and reliable means of energy improved and it led to the growth of energy harvesting alternatives to the natural source of energy from the environment.

The growth in the need for semiconductors in the technology space has led to a high level of technological advancements across small electronic devices. Energy has been enhanced in a broader form and the functionality of the technology has improved the density of battery energies. Also, piezoelectric materials the result of higher energy density which also improves the flexibility of the integrated system of studying its operations.

Researchers devote ample time into devising alternative forms of energy and to improve the lifespan of wireless sensors without reliance on batteries. The feasibility of the piezoelectric energy harvesting material is spread across four categories which include the ceramics also regarded as piezoceramic, the single crystals, the polymers, and the composite materials which are the coalescence of piezoceramic and single crystals with a mixture of polymers.