The production of nanoscale devices has drastically increased with the rise of technological applications. But a major drawback to the functionality of nanosize systems is the need for an equally small energy resource.
In order to address this issue, Hamid Foruzande, Ali Hadjnayeb and Amin Yaghootian from the Shahid Charmaran University of Ahvaz in Iran have been modeling new piezoelectric energy harvester (PEH) technology at the nanoscale level. The team determined how small-scale dimensions impact nonlinear vibrations and PEH voltage harvesting.
Piezoelectric materials generate electricity from the application of mechanical stress and are utilized in everything from cell phones to ultrasonic transducers. This electricity can be generated by vibration-induced stresses, allowing scientists to create PEHs. The PEHs can be miniaturized down to a micro- or nanosize and used with nanoscale devices.
"Nowadays, the need for new miniaturized wireless sensors is growing. These MEMS [Micro-Electro Mechanical Systems] or NEMS [Nano-Electro Mechanical Systems] sensors usually require a power source of their size," Hajnayeb said.
Piezoelectric energy harvesting is a process for converting energy in an environment into energy that can power small electric devices. Usually, this has been used for generating a self-sufficient energy supply. Self-sufficiency is highly desirable for nanoscale devices due to the complicated nature of small energy systems.
PEHs are becoming more popular for nanoscale applications due to their simple structures, higher energy densities and ability to be easily scaled down. Macroscale models have been extensively studied and provided a strong base to produce nanoscale models. Foruzande, Hajnayeb and Yaghootian are taking advantage of the adaptable qualities and have generated nanoscale PEH models that are based on the non-local elasticity theory.
"It's necessary to use this theory for other systems at nano-scale and also the sensors in nano-scale, which use piezoelectric materials," Hajnayeb said. "They have the same governing theory that we use in our article."
The team studied nonlinear vibrations and voltage based on nonlocal elasticity theory that states a point stress is dependent on the strain in a region around that point. With this theory, the team could derive nonlinear equations of motion with straightforward solutions. Their results showed that adding a nanobeam tip mass and increasing the scale factor would increase the generated voltage and vibration amplitude, which increases energy output.
Modeling micro- and nanoscale PEHs revealed the impact of size effects on expected output. The researchers found that the error of neglecting size is significant when comparing macro and micro PEHs. Neglecting various size effects revealed lower estimations of PEH vibrations.
Nanoscale sensor technology is a growing commodity in the scientific industry due to its extensive applications. With applications in medicine, engineering, physics and more, nanotechnology has a lot to gain from the use of a stable energy source, like newly modeled PEHs.
An article on this research appeared in AIP Advances.