MEMS Piezoresistive Pressure Sensor: A Survey

Shwetha Meti et.al. Int. Journal of Engineering Research and Applications www.ijera.com
ISSN: 2248-9622, Vol. 6, Issue 4, (Part - 1) April 2016, pp.23-31
www.ijera.com 23|P a g e
MEMS Piezoresistive Pressure Sensor: A Survey
Shwetha Meti*, Kirankumar B. Balavald*, B. G. Sheeparmatti*
*(Department of Electronics and Communication, Basaveshwar Engineering College, Bagalkot-587102
ABSTRACT
Piezoresistive pressure sensors are one of the very first products of MEMS technology, and are used in various
fields like automotive industries, aerospace, biomedical applications, and household appliances. Amongst
various transduction principles of pressure sensor piezoresistive transduction mechanism is widely used. Over a
decade therehas been tremendous improvement in the development of the design of piezoresistive pressure
sensor starting with the invention of piezoresistance in the silicon to the recent piezoresistive pressure sensor
materials. Because of its high sensitivity, high gauge factor, independent to the temperature, linear operation
over a wide range of pressure, and many more advantages. This paper provides survey of piezoresistive pressure
sensor including their pressure sensing mechanism, evolution, materials, design considerations, performance
parameter that to be considered and the fabrication process used
Keywords-MEMS, Pressure sensor, Piezoresistor, Silicon
I. INTRODUCTION
In conjunction with temperature, pressure
is one of the major physical quantities in our
environment. A pressure sensor often acts as a
transducer; it produces a signal as a function of the
pressure imposed. MEMS pressure sensors are
covering foremost part of the sensor market in
contemporary years and are fast developing with
brand new capabilities. Pressure sensors are used in
many applications like aerodynamics, biophysics,
automobile, safeguards and many more domestic
applications. Various types of pressure sensors can
be categorized based on the sensing mechanisms
they are. 1.1 Absolute pressure sensor measures
static, dynamic or whole pressure with reference to
a vacuum. 1.2 Gauge pressure sensor calculates the
pressure relative to atmospheric pressure. When it
shows zero, then the pressure it is measuring is
same as the ambient pressure. 1.3 Relative pressure
sensor measures static, dynamic or total pressure
with regards to the ambient pressure. 1.4 Optical
pressure sensor techniques include the use of
anphysical change in the optical fiber to detect the
strain due to an applied pressure. This technology
is employed in many challenging applications
where the measurement may be highly remote,
under high temperature, or may benefit from
applied sciences inherently immune to
electromagnetic interference. 1.5 Differential
pressure sensor measures the difference between
two pressures, one connected with each side of the
sensor. Differential pressure sensors are used to
measure many properties like pressure drops
through oil filters or air filters, fluid levels or flow
rates. 1.6 Piezoresistive pressure sensor uses
the piezoresistive effect of bonded strain gauges to
detect the strain due to an applied pressure,
resistance increasing as pressure deforms the
material. Common methods that uses piezoresistive
technologies are Silicon (Mono crystalline),
Polysilicon Thin Film, Bonded Metal Foil. 1.7
Capacitive pressure sensor uses a diaphragm and
pressure cavity to create a variable capacitor to
detect strain due to applied pressure, capacitance
decreasing as pressure deforms the diaphragm.
1.8Resonant pressure sensor uses the changes
in resonant frequency in a sensing mechanism to
measure stress, or changes in gas density, caused
by applied pressure.
Many MEMS instruments were
manufactured and commercialized from several
years and have reached consumer. The present
pressure sensors going through many challenges
that has to be used in the application like high
pressure. Temperature is a main factor in the
efficiency of MEMS pressure sensor, were these
have to be used in many applications like aerospace
utility and harsh environment. Consequently, for
this kind of environment special sensing devices
are requiring to adapt a high temperature and high
pressure environment. Among all the various type
of MEMS pressure sensor piezoresistive pressure
sensors are widely used, because these sensors
provides a high sensitivity and it allows a linear
operation over a wide range of pressure.
Piezoresistive pressure sensors are one of the very
first products of MEMs technology. Those products
are broadly used in biomedical applications,
automotive enterprises and household appliances.
The piezoresistive pressure sensor have mainly
been studied and commercialized because of their
high yield and wide dynamic range. A silicon based
pressure sensor is one of the major applications of
the piezoresistive sensor. Recently MEMS situated
technologies includes silicon (Si), silicon on
insulator (SOI), silicon on sapphire (SOS), silicon
carbide (SiC), steel, carbon nanotubes (CNT) and
RESEARCH ARTICLE OPEN ACCESS

diamond had been observed to be in a position to
furnish the critical ruggedness to be capable to
adapt and provide the better performance in harsh
environment. This paper focus on the survey of
MEMS based piezoresistive pressure sensor,
current trends involved in development of
piezoresistive pressure sensor and their outlook.
Section II explains about the evolutions of
piezoresistive pressure sensor. Principle and
sensing mechanism of piezoresistive pressure
sensor is explained in section III. Section IV is
about the materials that are used in the design of
diaphragm and their properties. Section V and VI
discuss about the performance parameter and the
design consideration of the piezoresistive pressure
sensor. The fabrication of the piezoresistive
pressure sensor is discussed in section VII.
II. EVALUTION OF PIEZORESISTIVE
PRESSURE SENSOR
Ever since the discovery of
Piezoresistance in silicon by C.S.Smith in1954 [1]
silicon based micro pressure sensors have been
extensively studied over the past three decades.
Pfann and Thurston [2] were among the first to
realize a working of MEMS based pressure sensor
designed using two longitudinal and two transverse
diffused piezoresistors in the Whetstone's bridge
for better sensitivity. Kanda [3] in his work has
presented a model which enables the calculation of
piezoresistive coefficients as a function of doping
concentration and temperature. Enhancing the
sensitivity has also been a main issue in the
research of micro pressure sensors. Design
modifications like employing a bossed diaphragm
and multiple diaphragms [4, 5] and material
modification by using phosphorous diffused
polysilicon piezoresistors [6] polymer diaphragms
and alternate piezoresistive materials [7-10] have
also been studied. The other technology can be
brought to solve the isolation problem of devices
and substrates, but increases the fabrication cost
greatly. The discovery of piezoresistive effect in
polysilicon in the 1970s [11] facilitates its
applications for sensing devices [12, 13]. As for
polysilicon, the p-n junction isolation is avoided, so
that the devices can work at higher temperatures.
Moreover, polysilicon based devices have the
advantages of low cost, facile processing and good
thermal stability, compared to homogeneous silicon
based devices. It can be seen that it is necessary to
investigate the piezoresistive properties of
polysilicon and built up the theoretical model. The
experimental results reported by other researchers
indicated that the GF of Polysilicon common films
(PSCFs, film thickness ≥ 200 nm) reaches the
maximum as the doping concentration is at the
level of 1019 cm3
, and then decreases drastically as
doping concentrations are increased further [14, 15-
17]. Based on this phenomenon, the existing
piezoresistive theories of Polysilicon were
established during 1980s~1990s and used to predict
the process steps for the optimization of device
performance.
Later years carbon nanotubes have drawn
much attention since their discovery in 1991
because of their unique electronic and mechanical
properties. In 1991, multi-walled nanotubes were
first discovered by Ijima by arc-discharge
technique when he saw fine threads in a bit of shoot
under electron microscope. The strands were very
thin and long tubes of pure carbon. SWNTs were
synthesized for the first time by Ijima and Ichihashi
[18] and Bethune et al. [19] in 1993 using metal
catalyst in arc-discharge method. Laser-ablation
technique was used by Thess et al. [20] in 1996 to
produce bundles of aligned SWNTs. For the first
time, catalytic growth of MWNTs by CVD was
proposed by Yacaman et al. [21]. Liu [22] and Dai
[23] demonstrated that piezoresistive pressure
sensors can be realized with CNTs. They grew
SWNTs on suspended square polysilicon
membranes. When uniform air pressure was
applied on the membranes, a change in resistance
in the SWNTs was observed. Moreover, the
membrane was restored to its original condition
when the gas was pumped out, indicating that the
process is reversible. Dharap et al.[24] argued that
the conventional sensors have disadvantage that
they are discrete point, fixed directional, and are
not embedded at the material level. To overcome
these limitations, they developed a CNT film
sensor for strain sensing on macro scale. The
sensor was based on the principle that the
electronic properties of CNTs change when
subjected to strains. In recent years high
temperature pressure sensor is one of the hot
research topics in the industry. Because of the
special environments they are used in, the
requirements for the design and manufacture of the
sensor are very strict. It is important to research
high temperature pressure sensors for every walk of
life [25, 26]. So Silicon carbide (SiC) has been
recognized as an appropriatesemiconductor
material for harsh environments such asspace
applications and terrestrial applications in the
aeronautical,automotive and petrochemical fields
proposed Staufferet al; George et al. 2006 Many
studies show thatSiC devices are capable of
operating well in these applicationsthat involve
high-temperature, high-radiation andcorrosive
environment by Azevedo and Jones;
WrightandHorsfall [27, 28] 2007.
Another material that can withstand the
high temperature and high pressure is a SOI. We
know that the temperature dependence of the

piezoresistive effect in silicon is well documented
in the literature. It is known how the piezoresistive
coefficients change with the temperature. The
temperature limit has been verified up to 175 °C for
silicon sensors and up to 500 °C for silicon-on-
insulator (SOI) technology [29] by Fraga et al.
2011. Later Haisheng San, Zijun Song, Xiang
Wang, Yanlizhao, and Tuxi Y. U, proposed that
the silicon piezoresistive pressure sensor is a
mature technology in industry, but when the
pressure sensors are operated in extremely harsh
environment, such as vibration, shock and
environment conditions with humidity,
alkalescency or acidity, electrostatic particles and
so on, its requirement in terms of reliability and
stability is more rigorous than that of many
advanced applications so for these application we
have to choose a SOI rather than silicon [30].
III. PIEZORESISTIVE PRESSURE
SENSING MECHANISM
Piezoresistive, capacitive, optical,
resonance, acoustic transduction principle used in
the contemporary work within the progress of the
micro machined pressure sensor modelling, design
and fabrication used to be reviewed in [31]. Among
these pressure sensor transduction principle,
piezoresistive and capacitive transduction
mechanisms have been widely adopted in various
fields. Many commercialized MEMS pressure
sensor [32-36] uses a piezoresistive transduction
mechanism in order to shows the pressure change
in the resistance. Most researchers preferred
piezoresistive technique, because the properties of
silicon material have been well established and the
facilities of current silicon foundry can be utilized
for batch fabrication. And also piezoresistive
pressure sensor has excessive high gauge factor but
it has 0.27% per °C of temperature coefficient of
Piezoresistivity (TCP). The design of piezoresistive
pressure sensor consists of piezoresistive element
placed on a top of the diaphragm. Placement of
piezoresistive element on the square diaphragm is
very important design consideration to achieve the
required sensitivity. The optimal location to place
the piezoresistive material would be in the region
of high stress on the diaphragm. Then these
resistors are connected in the form of Whetstone's
bridge [1, 37]. The application of pressure beneath
the sensor causes a deflection of the membrane and
this causes a change in resistance of the
piezoresistive elements. As a result, the calculation
of stress distribution and deflection in accordance
with the applied pressure becomes pivotal.
These forms of piezoresistive based
transducers depend on the piezoresistive effect
which occurs when the change in electrical
resistance of a material in response to the
mechanical strain is applied [38]. In metals, this
effect is realized when the change in geometry with
applied mechanical strain results in a small increase
or decrease in the resistance of the metal. The
piezoresistive effect in silicon is primarily due to its
atomic level. As stress is applied, the average
effective mass of the silicon carrier will either
increases or decreases (depending on the
orientation of the crystallographic, direction of the
stress, and the direction of the current flow). This
type of change alters the silicon carrier mobility
and hence it results in the change in its resistivity.
When piezoresistive element are placed in the
Wheatstone bridge configuration and it is attached
to the pressure-sensitive diaphragm, a resistance
change in the material is converted in to an output
voltage which is proportional to the applied
pressure as shown in the Fig.1.
Fig.1. Conventional pressure sensor model
Fig.2. Wheatstone bridge circuit.
Fig.2. shows the Wheatstone bridge
circuit, a Wheatstone bridge consists of a four
piezoresistive material labeled as R1, R2, R3 and R4
respectively. The resistance [R] of a piezoresistive
material is given by
R= ρ
𝑳
𝑨
(1)
Where ρ is the resistivity of a piezoresistor, L is the
length of a piezoresistor; A is the area of a
piezoresistor. Wheatstone bridge is mounted on the
diaphragm. When the pressure is applied to the
diaphragm, the diaphragm experiences the sheer
stress due to which the diaphragm deforms in the
direction of pressure imposed. Due to the
deformation of the diaphragm, the piezoresistors
mounted on the diaphragm in a Wheatstone bridge
format stretches. As the piezoresistors stretches, the

length increases while the area decreases. From
equation (1), if length increases and area decreases,
there will be incremental change in the resistance
of a piezoresistors and effectively decreases the
output voltage.
IV. MATERIALS OF PIEZORESISTIVE
PRESSURE SENSOR
In the above discussion it is clear that
depending on the application we have to use a
different piezoresistive material for the model, like
silicon (Si), silicon on insulator (SOI), silicon on
sapphire (SOS), silicon carbide (SiC), steel, carbon
nano tubes (CNT) and diamond. However the
principle remains same as the piezoresistive
mechanism of pressure sensing. The material used
to design the diaphragm on which the
piezoresistive materials are placed, plays on very
important role in deciding the application of a
pressure sensor. Table 1 and 2lists the properties of
various diaphragm and piezoresistive material
respectively.
Table 1 Properties of various diaphragm materials
Table 2 Properties of various
piezoresistivematerials
In the piezoresistive pressure sensor
output signal is from the Wheatstone bridge. The
resistance of the bridge is distributed in four
directions. The output signal Vout is Vin∆R/R. Vout
is the output voltage (V), Vin is the input signal
voltage (V), ∆R is the change in resistance (KΩ),
and R is the initialvalue of the resistance (KΩ). The
amount of change in voltage sensitivity of resistors
is [39].
∆R/R = 𝛑𝒍 𝛔𝒍 + 𝝅 𝒕 𝝈 𝒕 (2)
Where 𝜎𝑙is the longitudinal stress parallel to the
current direction in the internal of resistance
(N/𝑚2
), 𝜎𝑡is the transverse stress perpendicular to
the current direction (N/𝑚2
), π𝑙 is the longitudinal
piezoresistive coefficient of silicon (𝑚2
/𝑁), the
same direction as the longitudinal stress, π𝑡is the
transverse piezoresistive coefficient of silicon
(𝑚2
/𝑁), the same direction as the transverse stress.
Table 3 shows the piezoresistive coefficient for
<100> silicon wafer.
Table 3 Piezoresistive coefficients of silicon
V. PERFORMANCE PARAMETERS
When the pressure is applied on the diaphragm, it
tends to get deformed, having a maximum
displacement at the centre of the diaphragm. The
value of displacement decreases near the fixed ends
of the diaphragm. The quantity of displacement is
measured at the centre of the diaphragm [40] using
the following equation
X =
𝟎.𝟎𝟎𝟏𝟐𝟔𝑷𝑳 𝟒
𝑫
(3)
Where P is the Pressure applied on the diaphragm,
L is the Length of the diaphragm, and D is the
Bending rigidity of the diaphragm material and is
given as
D =
𝑬𝒕 𝟑
𝟏𝟐(𝟏−𝒗 𝟐)
(4)
Where E is the Young’s Modulus of diaphragm
material, t is the thickness of the diaphragm, and v
is the Poisson’s ratio of the diaphragm material.
The amount of sheer stress experienced at the mid-
point of the diaphragm [41] is given as
ρ = (
𝑳
𝒕
) 2
(5)
It can be seen from (3) and (5) is that, increase in
the pressure applied on the diaphragm, increases
the sheer stress at the mid-point of the diaphragm,
also increases the displacement or deformation of
the diaphragm. The displacement of the diaphragm
also depends on the dimensions of the diaphragm
as well as the stiffness property (Young’s modulus)
of the diaphragm material. When the pressure is
applied on the diaphragm with four blocks as
piezoresistor, the stress induced in the diaphragm
change the resistance of piezoresistor due to
piezoresistive effect. The change in the resistance
of the piezoresistor is denoted by ΔR. Due to the
deformation of the diaphragm in the direction of
pressure applied, it is said that the length of the
piezoresistor increases which in turn increases the
resistance of the piezoresistive material (using
Sl.
No
Materials Density Young’s
Modulus
Poisson’
s ratio
1. Silicon di oxide 2270 70 0.17
2. Poly Silicon 2320 169 0.22
3. Steel AISI 4340 7850 205 0.28
4. Al203 3970 393 0.27
5. Si3N4 3310 317 0.23
6. Germanium 5323 103 0.26
7. Al 2700 70 0.25
8. Cu 8960 120 0.34
Sl.
No
Materials Density Young’s
Modulus
Poisson’s
ratio
1. Single
crystalline Si (n,
p type)
2270 70 0.17
2. Carbon
Nanotubes
1600 1000 0.2
3. Diamond 3.5 10.35 ---
4. SIC 3.21 476 0.19
5. Silicon 2330 160 0.22
6. SOS 3.97 250-400 0.29
7. Polycrystalline
Si
2330 160 0.23
Sl.
No
Wafer
type
π𝑙 π𝑡 Orientation
1. P-type -31.6 -17.16 <110>
2. N-type 71.8 -66.3 <110>

equation 1). Thus it can be concluded that, as the
pressure increases, the resistance of the
piezoresistor will also increases linearly.The next
parameter is the output voltage across the
Wheatstone bridge. The output voltage of the
Wheatstone bridge depends on the input voltage
applied to the bridge circuit and also the resistance
values of all the four piezoresistive materials.
Hence, as the resistance of the piezoresistive
materials changes due to the applied pressure, the
output voltage of the Wheatstone bridge also
varies. The output voltage [Vout] across the
Wheatstone bridge circuit is given by,
Vout = [
𝑹𝟐𝑹𝟑−𝑹𝟏𝑹𝟒
(𝑹𝟏+𝑹𝟐)(𝑹𝟑+𝑹𝟒)
] Vin (6)
Where Vin is the Input voltage applied to
Wheatstone bridgefrom (6), when R2R3 = R1R4,
Vout= 0. This means that the bridge is in the
balanced condition and theoretically no pressure
is applied onto the diaphragm. When there is no
pressure on the diaphragm, the resistance values
of all the piezoresistive elements will be
theoretically identical, hence Vout = 0. But
practically it may be difficult to fabricate the
piezoresistive elements of equal resistances, due
to which the output voltage may not be zero when
no pressure is applied. The relation of electric
field in the vicinity of surface of the diaphragm
with applied stress is given by (7).
E = ρJ + ρρJ (7)
Where ρ is the resistivity of piezoresistors, J is
the current in piezoresistors, and Δρ is the
induced change in resistivity. This is given by the
equation
ρρ= ρ. ρ
Where π is the piezoresistance tensor and γ is the
shear stress given by (5).The performance of any
model can be estimated based on the sensitivity
of the sensor to the pressure applied and the
gauge factor. For the system to be better, it should
be highly sensitive. In other words, there should
be large decrease in the output voltage and large
increment in the resistance of piezoresistive
element due to a small increase in the pressure
applied to call a device as highly sensitive. Gauge
factor is another parameter which determines the
performance of the piezoresistive pressure sensor
[42]. The Gauge factor of the pressure sensor is
the change in resistance to the amount of
volumetric strain acting on it. It is given by
G =
∆𝑹
𝑹𝜺
(8)
Where ε is the Strain of the pressure sensor
The Gauge factor value should be large
(in the range of 500 to 1000) to indicate the better
performance of the pressure sensor.The
sensitivity of the pressure sensor is defined as the
relative change in the output voltage per unit of
applied pressure [43]. The sensitivity of the
piezoresistive pressure sensor is given by.
S=
𝟏
𝑽𝒊𝒏
∆𝑽
∆𝑷
(9)
Where S is the sensitivity of the pressure sensor,
ΔV is the change in the output voltage, and ΔP is
the change in the pressure applied. The output
voltage of the pressure sensor without any pressure
being applied is called an offset voltage. This is due
to mainly two reasons. The first one is due to some
residual stress on the membrane. And the second
one, which is main reason, is variability in the four
resistors. While the resistors are processed at the
same time, there are some variations. The offset
voltage can be compensated by connecting external
resistors. It can be compensated using
compensating resistors along with electronics.
VI. DESIGN CONSIDERATION
6.1. Fracture Stress:
Fracture stress is a property which
describes the ability of a material containing a
crack to resist fracture, and is one of the most
important properties of any material for many
design applications. The linear-elastic fracture
stress of a material is determined from the stress
intensity factor at which a thin crack in the material
begins to grow. It is denote (σfracture)
6.2. Yield Strength:
A yield strength or yield point is the
material property defined as the stress at which a
material begins to deform plastically. Prior to the
yield point the material will deform elastically and
will return to its original shape when the applied
stress is removed. Once the yield point is passed,
some fraction of the deformation will be permanent
and non-reversible.
6.3. Burst Pressure:
Another important design consideration of
a piezoresistive pressure sensor is a burst pressure.
We know that as the applied pressure on the
diaphragm increases, the stress on the diaphragm
increases correspondingly. As a result, when the
maximum stress on any portion of the diaphragm
exceeds the yield strength of the diaphragm
material, the diaphragm will burst. While this burst
pressure governs the maximum operating pressure
of a pressure sensor, the linearity of operation
determines the maximum pressure up to which the
sensor can be used within the limits of the specified
accuracy. The burst pressure is decided by a
number of factors including diaphragm shape,
thickness, lateral dimensions, ruptures stress of the
material and diaphragm surface roughness and is
given by [44].

𝑷 𝒃=
𝟑.𝟒𝑭 𝑴𝒂𝒙 𝒉 𝟐
𝑨(𝟏−𝒗 𝟐)
(10)
Where 𝐹 𝑀𝑎𝑥 is theFacture stress, h is the
Diaphragm thickness, 𝑣is the Poisson's ratio, A is
the Diaphragm area.
6.4. Diaphragm dimension:
As the stress on the piezoresistors is due to
the stress on the diaphragm, it is important to
choose the thickness and size of the diaphragm
carefully in order to obtain the best output
characteristics from the sensor. Pressure sensors
with thinner diaphragms give better sensitivity
whereas thicker diaphragm gives better linearity.
Usually, the diaphragm in a pressure sensor is
modified as a square diaphragm with all the edges
clamped. A diaphragm can be considered as a thin
diaphragm, if the ratio of thickness to the length of
diaphragm is less than 1/20, [44]. The small
deflection theory for bending of thin plates assumes
that the deflection of midpoint of surface of the
diaphragm must be small compared to the thickness
of the plate and the maximum deflection must be
less than 1/5th
of the thickness of the diaphragm
[45].
6.5. Temperature Coefficient
ofResistance(TCR):
The change in the resistance of the
material per degree Celsius change of temperature
is known as the temperature coefficient of
resistance. A positive coefficient of the material
means that its resistance increases with increases in
the temperature (Pure metal typically have a
positive temperature coefficient of resistance). A
negative coefficient of the material means that its
resistance decreases with an increases in the
temperature (Semiconductor materials like carbon,
silicon, germanium typically have a negative
temperature coefficient of resistance). The equation
for the TCR is given by,
R= Rref[1+ρ(T-Tref)] (11)
Where α is the temperature coefficient of
resistance, R is the resistance of the material at
temperature T, Rref is the reference resistance, T is
the temperature in degree Celsius, and Tref is the
reference temperature.
VII. FABRICATION METHODOLOGY
Many fabrication methods have been
investigated to date. They all aim at a thin
monocrystalline silicon film on top of an insulator
with defect densities as low as in bulk material. The
best compatibility with standard silicon processing
techniques can be attained with sandwich
structures. A typical fabrication of the
piezoresistive pressure sensor is shown in Fig.3. It
is made up of <100> crystal orientation of the
silicon wafer and a membrane has been formed by
an anisotropic etching using a KOH etch stop, in
the <111> plane. Due to the nature of this etch; the
sides of the membrane are oriented along <110>
direction.
Fig.3. Fabrication of the piezoresistive pressure
sensor
A cross sectional view of fabrication of a pure
silicon based piezoresistive pressure sensors using
a standard silicon IC process is shown in the Fig.4.
The process of patterning the thin uniform layer of
silicon substrate on the wafer surface. The pure
silicon is hardened by baking and then selectively
removed by projection of light through a reticle
containing mask information. To form the
diaphragm selectively removes unwanted material
from the surface of the wafer using wet-etching
technique. In oxidation process wet oxidation
molecule convert silicon on the top the wafer to
silicon dioxide. After the deposition of silicon
dioxide layer piezoresistors are placed on the
diaphragm by diffusing the P-type silicon to form
bridge between the piezoresistors.
Fig.4. Cross sectional view of fabrication
ofpiezoresistive pressure sensor
VIII. CONCLUSION
Research activity in the areas related to the
piezoresistive pressure sensor is very broad and it
has made a phenomenal growth. In this paper, an

attempt has been made to provide a review on
piezoresistive based pressure sensors, their various
mechanisms, materials used to design the
piezoresistive pressure sensor, different fabrication
process; performance parameters for the
piezoresistive pressure sensors are discussed. The
piezoresistive pressure sensor based on Wheatstone
bridge circuit is widely used by many reported
works. The exceptional properties, which allow
piezoresistive pressure sensors to be used in
sensors, has also been reviewed. MEMS pressure
sensor based on piezoresistive transduction
mechanism has lot of scope due to its high
sensitivity, stability and high temperature.
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Ms SHWETHA METI obtained her B.E degree in
Basaveshwar Engineering College Bagalkot. Her
area of interest includes MEMS, Piezoresistive
pressure sensor, Capacitive pressure sensor, Digital
signals processing.
Prof. KIRANKUMAR. B.
BALAVALADcompleted his
M.Techfrom
VishweshwaryyaTechnological
University, Belagavi, Karnataka,
India in the year 2010. He is
pursuing his Ph.D in the area of
MEMS Piezoresistive Pressure Sensors. Presently
he is serving as, Assistant Professor, Department of
Electronics and Communication Engineering,
Basaveshwar Engineering College, Bagalkot,
Karnataka, India. He has published 20 papers in
national and international conference and journals.
His area of interest includes MEMS, Pressure
sensors, Electro thermal actuators, Wireless
networks, Statistical signal processing.
Dr. B. G. Sheeparmatti hascompleted his Ph.D in
the area of MEMS from Karnataka
University Dharwad, Karnataka,
India. He us currently serving as a
professor in Electronics and
Communication Engineering,
department Basaveshwar
Engineering College, Bagalkot, Karnataka, India.
He has successfully completed 2RPS schemes
approved by AICTE in the area of MEMS. He has
setup a low cost MEMS fabrication lab at the
department of Electronics and Communication
Engineering. He has more than 60 national,
international conference and journal papers to his
credit. His area of interest includes MEMS, MEMS
based actuators & sensors, Electromagnetic sensors
and actuators, Embedded system etc.
Electronics and Communication
Engineering from the Basaveshwar
Engineering College Bagalkot.
Pursuing Master degree in Digital
Communication from the
Basaveshwar

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