Mems Based Energy Harvesting
Guided byDr. M.R. BaijuProfessorDept. of ECECET
Presented byVISAKH.V
M4 AEI,ROLL NO:12
Energy Harvesting College of Engineering, Trivandrum
Overview
Energy Harvesting College of Engineering, Trivandrum
Characteristics of Various Vibration Sources
According to the study only the first 500 Hz of the spectra is important.
First, there is a sharp peak in magnitude at a fairly low frequency with a few higherfrequency harmonics.
Another observation is that the fundamental vibration frequency for almost allsources is between 70 and 125 Hz.
Energy Harvesting College of Engineering, Trivandrum
Vibration to Electricity Conversion Model
Figure: Generic vibration converter
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Vibrations to Electricity Conversion Methods
There are mainly three main methods for converting the energy from vibrations toelectrical energy. They are
Electromagnetic Power Conversion
Elecrostatic Power Conversion
Piezoelectric Power Conversion
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Piezoelectric Power Conversion
Piezoelectric Power Conversion
The constitutive equations for a piezoelectric material are given in equations ?? and ??.
δ =σ
Y+ dE (1)
D = εE + dσ (2)
where:δ is mechanical strainσ is mechanical stressY is the modulus of elasticity (Young’s Modulus)d is the piezoelectric strain coefficientE is the electric fieldD is the electrical displacement (charge density)ε is the dielectric constant of the piezoelectric material
Energy Harvesting College of Engineering, Trivandrum
WORK DONE AND RESULT
The work done for the thesis includes the following.
Familiarized Coventorware(Design and Analysis Software)
Design and Analysis of Cantilever Beam in Coventorware
Design an Analysis of Piezoresistor in Coventorware
Familiarized Mems+
Interfaced Mems+ with Matlab
Designed Mems Switch in Mems+
Analysed Mems Switch in Matlab
Designed Energy Harvester Structure in Mems+
Energy Harvesting College of Engineering, Trivandrum
Design and Analysis of Cantilever Beam
Design and Analysis of Cantilever Beam
Figure: Solid Model of Cantilever Beam
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Design and Analysis of Cantilever Beam
Modes of Vibration
Mode 1
Mode 2
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Design and Analysis of Cantilever Beam
Mode 3
Mode 4
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Design and Analysis of Cantilever Beam
Mode 5
Mode 6
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Design and Analysis of Cantilever Beam
Pull in with Cosolve
Figure: Pull in Analysis Plot
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Design and Analysis of Cantilever Beam
Liftoff with Cosolve
Figure: Lift off Analysis Plot
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Design and Analysis of Piezoresistor
Solid Model of Diaphragm
Figure: Solid Model of Diaphragm
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Design and Analysis of Piezoresistor
A new MemPZR analysis is set up using the above model. And with a voltagedifference of 1V applied to the electrodes and a 0.2N of force appied , the resultingcurrents at the electrodes is obtained.
Patch voltage Patch Current % change in currentin1 1 1.462025E08 4.430218in2 1 1.332666E08 -4.809469out1 0 -1.462025E08 4.430218out2 0 -1.332666E08 -4.809469
Energy Harvesting College of Engineering, Trivandrum
Mems Switch
Mems Switch Model in Mems+
Figure: Mems Switch Model in Mems+
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Mems Switch
Simulink Model
Figure: Simulink Model
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Mems Switch
Pullin Voltage
Figure: Simulink Model
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Energy Harvestor Circuit in Mems+
Materials Used
The piezoelectric energy harvesting structure process flow is designed in MEMS+. Thematerials used for the process are
Silicon (Proof Mass)
SiO2
AlN(Piezoelectric Material)
Al(Electrical Contact)
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Energy Harvestor Circuit in Mems+
Process Flow
Silicon material is deposited over a substrate to define the proof mass layer andalso the anchor part.This layer has a height of 400 um.
The next step is the deposition of oxide layer over this layer. The oxide layer has athickness of about 0.5 um .
Then another layer of silicon is deposited over this layer with a thickness 5 um.
Then the piezoelectric material AlN is deposited over this layer with a thickness of1 um.
After etching , Aluminium is deposited to define the electrode contacts.
Energy Harvesting College of Engineering, Trivandrum
Energy Harvestor Circuit in Mems+
Mask Layouts
Figure: Mask for the first Silicon layer
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Energy Harvestor Circuit in Mems+
Figure: Mask for the first SiO2layer
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Energy Harvestor Circuit in Mems+
Figure: Mask for the Si layer
Energy Harvesting College of Engineering, Trivandrum
Energy Harvestor Circuit in Mems+
Figure: Mask for the AlN layer
Energy Harvesting College of Engineering, Trivandrum
Work to be Done
System level Analysis of Energy Harvester Circuit Using Matlab and Mems+
FEM Analysis of the EH circuit using Coventorware
Multiphysics Analysis of the circuit using Comsol
Energy Harvesting College of Engineering, Trivandrum
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Energy Harvesting College of Engineering, Trivandrum