

Articles
by
B.Y. Majlis 
Total Records (
4 ) for
B.Y. Majlis 





M.S. Bhuyan
,
B.Y. Majlis
,
M. Othman
,
Sawal H. Md Ali
,
C. Kalaivani
and
Shabiul Islam


Dependency on battery as the only power source is putting an enormous burden in many applications due to size, weight, safety and lifetime constraints etc. Emerging applications like wireless sensor networks, implantable medical devices, heating ventilation and air conditioning system for indoor and automotive environmental comfort are examples of such class. In addition, it is often impractical to operate these systems using battery owing to the difficulty in replacing battery. Therefore, the ability to harvest ambient energy is vital for battery less operation. In this study, novel modeling of a micro energy harvester aimed at harvesting energy from fluidflow induced vibration, through piezoceramic cantilever means is presented. The strategy pursued in order to harvest energy in low fluidflow conditions, couples vortex shedding from a Dshaped bluffbody to a piezoelectric cantilever attached to the bluffbody. Fluidic pressure impulse on piezoelectric cantilever beam due to vortex shedding results in lift force. Fluctuation of fluidic pressure causes flexible cantilever to vibrate in the direction normal to fluid flow. Deformation of the piezoceramic cantilever converts mechanical energy into electrical energy through its crystalline structure. COMSOLmultiphysics simulations and results are presented in details to demonstrate the feasibility of the harvester in low fluidflow velocities conditions ranging 15 m sec^{1}. In a (200x150x150) μm^{3} rectangular duct, at 5 m sec^{1} fluid velocity, the (50x40x2) μm^{3} piezoelectric cantilever experienced concluding statement concluding statement 3088 Pa stress. The resulting cantilever deflection produced 2.9 mv, which is sufficient to drive an ultralowpower rectifier circuit. This harvester is designed as a useful power source to replace or supplement batteries. 




Mohammad Zayed Ahmed
,
M.S. Bhuyan
,
A.K.M. Tariqul Islam
and
B.Y. Majlis


This study presents the fabrication of a 3D microtransformer using MEMS technology in 10600 kHz frequency range. The fabrication processes is developed for highperformance and lowcost realization with respect to planner design. The coil winding and the magnetic cores were fabricated by electrodeposition using copper and Ni/Fe Permalloy materials, respectively. In stepup configuration, the microtransformer achieved 73.75% efficiency. The inductance achieved was 90 and 164 μH for primary and secondary coils, respectively. Characterization results and fabrication process of the fabricated transformer (2560x1240 μm) on alumina ceramic substrate are presented. 





M.S. Bhuyan
,
B.Y. Majlis
,
M. Othman
,
Sawal H. Md. Ali
and
Shabiul Islam


This study presents multiphysics threedimensional finite
element simulation of a fluid flow based selfexcited micro energy harvester.
This micro energy harvester is modeled inside a micro fluid channel to convert
fluid flow energy into fluid oscillations. Investigations are carried out for
the impact of low fluid flow velocity ranging 15 m sec^{1}, associated
voltage generation by piezoelectric means and various mechanical analyses to
enhance the performance and robust design considerations. The piezoelectric
micro cantilever is attached to a Dshaped bluff body. An axial fluid flow and
the Dshaped bluff body interaction generate Karman Vortex Street in the wake
of the bluffbody. Vortex shedding causes an asymmetry in pressure distribution
on the surface of the bluff body which results in timedependent forces acting
on the attached flexible micro cantilever. Due to structural vibrations induced
by the uniform and steady fluid flow, periodic strains are generated in the
piezoelectric cantilever which converts the strain energy into electrical charge.
Finite Element Analysis Software namely COMSOL Multiphysics are used for the
Harvester Model and simulation. In a 200x150x150 μm^{3} rectangular
duct, at 5 m sec^{1} fluid velocity, the 50x40x2 μm^{3}
piezoelectric cantilever experienced 3088 Pa stress with cantilever tip displacement
around 60 μm. A maximum voltage of 2.9 mV was recorded at 5 m sec^{1}
fluid velocity that is sufficient to drive an ultralowpower rectifier circuit
for a complete energy harvesting system. This study in detail describes the
harvester device modeling and finite element analysis in COMSOL. Instead of
using ambient parasitic vibration, this Energy Harvester Model directly utilize
fluid flow energy to improve harvesting capability. The micro energy harvester
selfcharging capability makes it possible to develop untethered sensor nodes
that do not require any wired connection or battery replacement or supplement
batteries. Integration of fluid flow based micro energy harvester device for
the autonomous sensor network such as automotive temperature and humidity sensor
networks. 




M.S. Bhuyan
,
Sawal H. Md. Ali
,
M. Othman
,
B.Y. Majlis
,
Shafii A. Wahab
and
Shabiul Islam


The study presented in this research targets the modeling and analysis of a 31 transverse mode type piezoelectric cantilever beam for voltage generation by transforming ambient fluid induced vibration energy into usable electrical energy. Piezoelectric materials have the ability to convert mechanical forces into an electric field in response to the application of mechanical stresses or vice versa. This property of the materials has found applications in sensor and actuator technologies and recently in the new field of energy harvesting. A mathematical model for energy harvesting by a piezoelectric cantilever beam device, based on classical beam analysis is presented. The optimization algorithm is implemented in Matlab, based on four physical dimension parameters of the energy harvesting cantilever. The optimal cantilever design from the theoretically derived algorithm determines four physical dimensions parameter to maximize output power. The output power is used to evaluate the performance of the energy harvester. Some interesting aspects that affect the generation of power are discussed. From this analysis, it is found that increasing the frequency of the vibration improve the output power while beyond a certain value further improvement can not be achieved by simply increasing the vibration frequency. Moreover, output power of the energy harvester is found as a function of external resistance. The model predicted anoptimized design with maximizes output power of 0.9 mW at a natural frequency of 200 Hz. Piezoelectric cantilever based energy harvester device can potentially replace the battery that supplies power in microwatt range necessary for operating wireless sensor devices. 





