MEMS-based Reconfigurable Energy harvesting Device Using the Couple Cantilevers
Energy Harvesting methods are the most important area of Research since last decade, to bring forward the alternative methods for conventional power sources and generators at microscale and low powered devices. Most of these techniques use the ambient energy present in the environment where photovoltaic’s and micro vibrational harvesters are the important contenders at micro/nanoscale. The primary fascinates in the technology is that the capability of the devices having and acting as independent power sources that can supply the power wireless devices at micro scales and these be the alternatives too bulky batteries. The main principle of vibrational energy harvesting is to covert the Kinetic energy available in the environment and having non-location specific being best suited to harsh operating environments. There are reported energy harvesters for industrial applications to human-powered wearable devices. The harvesters are tuned in accordance with the ambient vibrations and these devices are dimensions and material specific. And in most of the vibrational energy harvesters are cantilever’s base devices at micro/nanodevices depending upon the ambient vibrational frequency. Once the ambient vibrational frequency changes these devices are to be tuned and it is very difficult once the devices are fabricated. But beforehand running depends upon the dimensions, gravity of mass, stiffness and straining the structure.
This paper uses the couple cantilevers for the reconfigurable frequency of operations that can be tuned to three ambient vibrational frequencies using its localised modes of operations. The microdevice is threefold where it's having three independent modes wherein each individual mode the cantilevers vibrate at principle modes which are most feasible for Energy harvesting using Piezoelectric principle. In the first mode, at the lowest resonance frequency, the three cantilevers oscillate in phase with the same amplitude. In the second mode the central cantilever does not move, while the two lateral cantilevers oscillate with opposite phase and equal amplitude and last mode the central cantilever vibrates with less amplitude. The amount of energy harvested in three cases might be not be having same resolution due to its different vibrating amplitudes, but having advantage harvesting all three modes by a single device. This device can be improved with an array of structures and there are eliminate the difficulty of fabrication with an array of dimensionally altered cantilever harvesters.
The modelling and simulation of the devices are carried out in COMSOL Multiphysics®
using structural physics and Eigen frequency analysis with the parametric sweep of the dimensions and material sweep for tuning the devices according to the ambient vibrational frequency and Coupled with piezoelectric devices. The study is carried with engine frequency analysis, stationary and frequency analysis to derive the output voltage and frequency modes. The achieved frequencies are around 313KHz, 316KHz and 337KHz for device dimensions of 80 microns * 20-micron cantilevers and this can be scaled as per the ambient frequencies.