The document discusses capacitance variation in MEMS capacitors based on plate area, distance between plates, and different dielectric materials. It outlines the research significance, methodology, experimental details, results and discussion, and conclusion. The results show that capacitance increases with larger plate area, smaller distance between plates, and dielectric materials with higher relative dielectric constants. The capacitance variation can be utilized in applications such as wireless communications, sensing, and electronics.

2. Capacitance Variation Based on Plate
Area,Distance between the Plates and Different
Dielectric Materials.
Syed Absar Kazmi (Pakistan)
engrabsarkazmi@gmail.com
Department of Electrical and Computer Technology
Kulliyah of Engineering, International Islamic University of Malaysia

3. Outline
1.Introduction
2.Research significance
3.Methodology adopted
4.Experimental details
5.Results & discussion
6.conclusion
Fig 1. Comsol model design

4. So what exactly is MEMS ?
• Micro-Electro-Mechanical Systems (MEMS) is the
integration of mechanical elements, sensors, actuators,
and
electronics on a common substrate through the utilization
of
microfabrication technology or “microtechnology”.

5. Capacitors
• Composed of two conductive plates separated by an insulator
(or dielectric).
• Commonly illustrated as two parallel metal plates
separated by a distance, d.
C = e A/d
where e = er eo
er is the relative dielectric constant
eo is the vacuum permittivity Fig 2.Prallel plates of
capcitor

6. Effect of Dimensions
• Capacitance increases with
• increasing surface area of the plates,
• decreasing spacing between plates, and
• increasing the relative dielectric constant of the insulator
between the two plates.

7. MEMS Capacitor
• MEMS (Microelectromechanical system)
• Can be a variable capacitor by changing the distance
between electrodes.
• Use in sensing applications as well as in RF electronics.

8. Electrical Properties of a Capacitor
• Acts like an open circuit at steady state when connected to a
d.c. voltage or current source.
• Voltage on a capacitor must be continuous
• There are no abrupt changes to the voltage, but there
may be discontinuities in the current.
• An ideal capacitor does not dissipate energy, it takes power
when storing energy and returns it when discharging.

9. • Charge is stored on the
plates of the capacitor.
Equation:
Q = CV
Units:
Farad = Coulomb/Voltage
Farad is abbreviated as F
Energy Storage
Fig 3.Prallel plates of capcitor

10. Significance
The research is important in the following ways,
1. The capacitance during the varaition of distance between plates
was analyzed
2. The affect on capacitance due to changing the dielectric material
was keenly examined
3. Area of the plates was enlagred and investigated the variation in
capacitance keeping height constant.
4. Overall behavier of capacitor was noticed during all variation
for the implicaiton purposes.

11. Methodology Adopted
The over all methodology passed through the
following phases,
1. COMSOL multiphysic finite element analysis
software is implicated to simulate the capacitor
designed model.
2. Capacitance is analyzed by varying the
destacne between the plates and the dieelctric
materials.
3. By enlarging the plate area and keeping the
height constant capcitance was observed.
4. By getting all results formulated in graphs
and tubulized the data to be analyzed in
simplified way.
COMSOL
Changing Dielectric
& Distance
Plate Area
Examined results
Analyzed the
outcomces
Fig 4.Methodology flow

12. Experimental details
Building geometry is used for MEMS
capcitor model designed as per
desired parameters
Material defination to set up
the material properties as
conductor and insulator
Meshing of build geometry is
performed to achieve the
prescise result.
Tabular Compilation of
capcitance based on
varying factors.
Comprehensive Analysis of Results

13. RESULT & DISCUSSION
Capacitance variation is analayzed by two different approach using
COMSOL software.The simulated results are shown in table 1 &
2 and by graphs 1 &2
i) Variation of distance between plates and dielectric material
ii) Varying the plate area stimation results.
 Four different material were chosen for simulation purpose to
estimate the capacitance Air,SiO2,Nylon and PVC and distance
between plates varied from 9um to 36um
 The plate area varied from 50*50 to 230*230um and analyzed the
capacitance range.

14. RESULT & DISCUSSION
Capacitance variation by dielctric material
(Cont....)
Distancebetween the
plates(um)
Capacitance (pf) by dielectric materials
Air SiO2 Nylon PVC
10 0.01594 0.01881 0.01875 0.01831
14 0.01475 0.01838 0.01831 0.01777
18 0.01373 0.01799 0.01791 0.01724
22 0.01285 0.01761 0.01751 0.01674
25 0.01226 0.17341 0.01723 0.01639
28 0.01719 0.01707 0.01695 0.01604
31 0.01122 0.01681 0.01668 0.01572
34 0.01076 0.01656 0.01643 0.01541
36 0.01048 0.01641 0.01626 0.01521
Table (1)
The Table (1) shows the capacitance analysis by variation of distacne between
plates and for four dielectric materials.By results it can be analyzed that the air
as dielctric material has a drastic decay in capacitance as compared to
others.Furthermore the SiO2 and Nylon dielectric material’s capacitance varies
around the same range for whole variation.Howere PVC capcitance ranges in

15. RESULT & DISCUSSION
Capacitance analysis by varying plate area
(Cont....)
plotting values Plate area(um) Capcatance(pf)
1 50*50 0.014757
2 70*70 0.028924
3 90*90 0.04781
4 110*110 0.07142
5 130*130 0.09975
6 150*150 0.013281
7 170*170 0.017059
8 190*190 0.02131
9 210*210 0.026031
10 230*230 0.031226
The second model of MEMS capacitor was designed and examined
by the plate area variaiton while keeping hight constant at
20um.Above table is tubulized by varying the plate area from 50*50
to 230*230 and its very obvious to estimate that the capacitance
enhances by increasing the plate area.

16. RESULT & DISCUSSION
Capacitance graph for different dielectric
material and plate distance
Figure (8) The graph illustrates capacitance vs plate distance with the four
dielectric materials which are Air,SiO2,Nylon and PVC.The graph presents the four
line on plotting area.The dielectric material SiO2 and Nylon varies almost in same
range of capacitance whereas the PVC capacitance decreases at remarkable rate
.However,the dielectric as air has a drastic decay effect then all other dielectric
material.

17. RESULT & DISCUSSION
Capacitance graph for range of plate area
figure (3)
X-axis shows the plate area variation where as the Y-axis shows the
capcitance with scalling of 0.01 factor to make it more simpler.By figure () it
can be alnalyzed that the capacitance increasing gradualy by incresing the
plate area

18. Conclusion & Implications
This paper provides simplified analysis outcomes for MEMS capacitor.The
capcitance variation were keenly examined by enhancing the plate area,distance
between the plates and dielectric materials. The result demonstrates that , the
capcitance of MEMS capcitor incrememted by plate area and dielelectric strength of
material where as it decays with distance increses between plates.
This variation of capacitance is utillized in wide range of implications like,radio
astronomy, remote sensing, high speed point to point wireless local area networks,
broadband internet access, wireless HD, radar systems, weapon system, security
screening, medicine, aviation air-to-ground communications, shortwave

19. References[1] Tornatta, P.A. ; Cavendish-Kinetics, San Jose, CA, USA ; Gaddi, R.”Aperture tuned
antennas for 3G 4G applications using MEMS digital variable capacitor”
Microwave Symposium Digest (IMS), 2013 IEEE MTT-S International
[2]
[3] www.kaust.edu.sa/isl/tools/rf-mems-tutorial
[4] www.citycollegiate.com/capacitorXIIa.htm
[5] Qizheng Gu*, and Javier R. De Luis
Wispry “RF MEMS Tunable Capacitor Applications in Mobile Phones “ Inc., 20 Fairbanks, Suite 190 - 198
[6] www.learningaboutelectronics.com
[7] Zhiping Feng, Wenge Zhang, Bingzhi Su, Kevin F. Harsh, K. C. Gupta, V. Bright, and Y. C. Lee ,C AMPmode
“Design and Modeling of RF MEMS Tunable Capacitors Using Electro-thermal Actuators “
[8] A. M. Elshurafa and K. N. Salama P. H. Ho
“Modeling and Fabrication of an RF MEMS Variable Capacitor with a Fractal Geometry”
[9] DESIGN AND CHARACTERIZATION OF
MEMS VARACTOR
[10] Masayuki Miyazaki, Hidetoshi Tanaka, Goichi Ono, Tomohiro Nagano*, Norio Ohkubo,
Takayuki Kawahara, and Kazuo Yano
“Electric-Energy Generation Using Variable-Capacitive
LSI: Resonator for Power-Free “
[11] Charles L. Goldsmith, Andrew Malczewski, Zhimin J. Yao, Shea Chen, John Ehmke,David H. Hinzel
“RF MEMs Variable Capacitors for Tunable Filters”
[12] Aleksander
“Micromachined Electro-Mechanically Tunable
Capacitors and Their Applications to RF IC’s”
Dec, Member, IEEE, and Ken Suyama, Senior Member, IEEE

20. Thank you