Recent Application and Future Development Scope in MEMS

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056
Volume: 04 Issue: 02 | Feb -2017 www.irjet.net p-ISSN: 2395-0072
© 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 1445
Recent Application and Future Development Scope in MEMS
Mr. U. G. Phonde1, Mr. H. S. Daingade2, Mr. V. A. Patil3, Mrs. S. S. halunde4
1Assistant Professor, E&TC Engineering, ADCET, Ashta, Maharashtra, India
4Assistant Professor, E&TC Engineering, SITCOE, Yadrav, Maharashtra, India
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Abstract - This paper deals with recent
developments and future of micro-electromechanical
systems, or MEMS. Micro-Electro-Mechanical Systems
(MEMS) are extensively used in the field of scientific and
engineering. MEMS encompass the process-based
technologies used to fabricate tiny integrated devices
and/or systems that integrate functionalities from different
physical domains into one device Micro-Electro-Mechanical
Systems. Such devices are fabricated using a wide range of
technologies, having in common the ability to create
structures with micro- and even nanometer accuracies.
Micro-electromechanical systems (MEMS) are a process
technology used to create tiny integrated devices or systems
that combine mechanical and electrical components. They
are fabricated using integrated circuit (IC) batch processing
techniques and can range in size from a few micrometers to
millimeters.
Key Words: MEMS, MST, GPS,MOEMS, PDMS etc.
1. INTRODUCTION
This document is template. We ask that authors
follow some MEMS, an acronym that originated in the
United States, are also referred to as Micro System
Technology (MST) in Europe and Micromachining in
Japan. Regardless of terminology, the uniting factor
of a MEMS device is in the way it is made. While the
device electronics are fabricated using `computer
chip' IC technology, the micromechanical
components are fabricated by sophisticated
manipulations of silicon and other substrates using
micromachining processes.
MEMS, is a technology that in its most general
form can be defined as miniaturized mechanical and
electro-mechanical elements (i.e., devices and
structures) that are made using the techniques of
micro fabrication. The critical physical dimensions of
MEMS devices can vary from well below one micron
on the lower end of the dimensional spectrum, all the
way to several millimeters. Likewise, the types of
MEMS devices can vary from relatively simple
structures having no moving elements, to
extremely complex electromechanical systems
with multiple moving elements under the control
of integrated microelectronics. The one main
criterion of MEMS is that there are at least some
elements having some sort of mechanical
functionality whether or not these elements can
move. The term used to define MEMS varies in
different parts of the world. In the United States they
are predominantly called MEMS, while in some other
parts of the world they are called “Microsystems
Technology” or “micro machined devices”. These
devices (or systems) have the ability to sense, control
and actuate on the micro scale, and generate effects
on the macro scale.
Fig.1: Components of MEMS
1.1 Recent development:
The experience gained from these early MEMS
applications has resulted in an enabling technology
for new biomedical applications (e.g. Lab on Chip)
and optical or wireless communications, also
referred to as respectively Micro Opto Electro
Mechanical Systems (MOEMS), and Radio Frequency
MEMS (RF MEMS).

1.2 Lab-On-Chip
Biochips are biological microchips that host
reactions between DNA, proteins, chemical and
biological reagents on glass, silicon or plastic plates
in order to extract information.
The main advantages of Lab on Chip
components include ease-of-use, speed of analysis,
low sample and reagent consumption and high
reproducibility due to standardization and
automation. As is clear from the term Lab on Chip,
the goal is to place the entire process of a laboratory
onto a single chip. Micro fluidic systems therefore
typically contain silicon micro machined pumps, flow
sensors, micro channels, micro reactors and chemical
sensors. They enable fast and easy manipulation and
analysis of small volumes of liquids. The ability to
receive test results in a few hours or even minutes,
rather than a week or so, will make a vast difference
in diagnosis and treatment, but also in the patient’s
well being. There are three main application areas
for Lab on Chip: medical diagnostics, clinical
diagnostics and life science research.
Lab on chip concepts have been developed and
are being developed for many applications such as
SARS, leukemia, breast cancer, dipolar disorder and a
several infectious diseases.
From a unit shipment standpoint, Point of Care
diagnostics is the largest (potential) segment,
although in terms of turnover, the segment of life
science research is larger, thanks to higher chip
prices. Price of components here can run into several
hundreds of dollars, while for POC diagnostics a few
dollars or less is acceptable at most. Chips for
specialized clinical diagnostics tests operate
somewhere in the middle.
Fig.2 Lab on Chip
1.3 MOEMS
Optical communications has emerged as a
practical means to address the network scaling
issues created by the tremendous growth in data
traffic caused, in part, due to the rapid rise of the use
of internet. The most significant MOEMS based
products include, variable optical attenuators, optical
switching units and tunable filters. Their small size,
low cost, low power consumption, mechanical
durability, high accuracy, high switching density as
well as the low cost batch processing of these MEMS-
based devices make them a perfect solution to the
problems of the control and switching of optical
signals in telephone networks.
1.4 RF MEMS
RF MEMS constitute one of the fastest
growing areas in commercial MEMS technology. RF
MEMS are designed specifically for use within the
electronics in mobile phones and other wireless
communication applications such as radar, global
Positioning satellite systems (GPS) and steerable
antenna. The main advantages gained from such
devices include higher isolation and therefore less
power loss and an ability to be integrated with other
electronics. MEMS have enabled the performance,
reliability and function of these devices to be
enhanced while driving downs their size and cost at
the same time.
The technology includes passive devices such
as capacitors/inductors, filters and resonators (see
figure 3). But also active devices such as switches
(see figure 4). These low-loss ultra-miniature and
highly integrated RF functions can replace classical
RF elements and enable a new generation of RF
devices and systems. It must be stated that in spite of
considerable effort from the industry over the last
years, only a handful of companies have come close
to commercialization.
Fig. 3 Combdrive resonator

Fig.4 Schematic cross section RF MEMS switch
2. FABRICATION
Fig.5 Fabrication process flow: (a) Sensing element
layer fabrication process, (b) Interconnect layer, (c)
bonding two layer and make electrical connection out.
As shown in Fig. 5, the fabrication of the
sensor skin can be divided into 3 parts for clearly
explanations. The first part is fabricating the sensing
element layer shown in Fig. 5(a): First, two layers of
photo resist AZ-4620 is patterned on a plastic sheet
and a squeegee process is used to pattern the PDMS
sensing material [3], which is PDMS elastomer mixed
with 10% weight ratio MWNT. A further 90°C baking
in oven is used to solidify the patterned PDMS
sensing material, and then liquid PDMS is poured on
the sensing element with another plastic sheet on top
for easy transferring. After the liquid PDMS is cured
in 90°C oven for 10 minutes, the bottom plastic sheet
is peeled off. The second part is to make the electrical
interconnect layer shown in Fig. 5(b): the first step is
to pattern one layer of photo resist AZ-4620. Then
the patterned photo resist is baked on 200°C
hotplate for 20 minutes for reflow in order to reduce
flow resistance of micro fluidic channel. Following
that, liquid PDMS elastomer is spincoated at
1000/min and cured on the photo resist mould. For
easy transfer, a thick PDMS layer is reversibly
bonded on top of the micro fluidic channel layer.
Finally, the bottom plastic sheet is peeled off from
micro fluidic layer, and two through holes (500 μm in
diameter) are manually drilled as inlet and outlet.
The third part is to permanently bond the
aforementioned two layers together to form the
sensor skin shown as Fig. 5(c).
After processed in ICP Oxygen plasma for 15
seconds, they are bonded together by an apparatus
that can adjust within 20μm error, further followed
by baking for 10 minutes in 90°C oven. Then the
bottom plastic is carefully peeled off. Then liquid
metal is pumped by syringe through the inlet drilled
into the micro fluidic channel and make overlap on
the PDMS sensing element. After filling liquid metal
into the micro fluidic channel, thick PDMs bulk is
removed and a thin sensor skin is finally finished. In
order to make electrical connection out, a metal wire
is inserted into the holes to make contact with liquid
metal, and then liquid PDMS is dipped on and later
cured to hold the metal line.
3. RECENT APPLICATIONS
3.1 A directional microphone for hearing aids
inspired by ears of the fly Ormia ochracea.

Fig.6 A directional microphone for hearing aids inspired by
ears of the fly Ormia ochracea. (a) A picture for the chip
containing polysilicon diaphragms next to the fly Ormia
ochracea, (b) is a packaged microphone, and (c) is a SEM
picture of the torsional polysilicon diaphragm, which is the
backbone of the directional microphone.
3.2 Differential pressure sensors used in cars
and trucks diesel engines emissions systems
Fig. 7 Differential pressure sensors used in cars and trucks
diesel engines emissions systems. (a) A micro-diaphragm
with a piezoresistive 4-gauge bridge, (b) the packaged
device.
4. CONCLUSION:
The fascination in the MEMS technology
comes from their distinguished characteristics.
MEMS are characterized by low cost, which is a direct
consequence of the batch fabrication. They have
lightweight and small size, which is desirable for
compactness and convenience reasons. In addition,
this has opened the gates for new possibilities of
implementing MEMS in many places where large
devices do not fit, such as engine of cars and inside
the human body. Moreover, they consume very low
power, which not only does reduce the operational
cost but also enables the development of long-life
and self-powered devices that can harvest the small
amount of energy they need from the environment
during their operation.
REFERENCES
[1] Huan Hu, Kashan Shaikh and Chang Liu “Super flexible
sensor skin using liquid metal as Interconnect” IEEE
SENSORS 2007 Conference 1-4244-1262-5/07/$25.00
©2007 IEEE
[2] J. Engel, N. Chen, C. Tucker, C. Liu, “Flexible
Multimodal Tactile Sensing System for Object
Identification”, IEEE Sensors Conference, Korea,
October 2006.
[3] J. Engel, Jack. Chen, N. Chen, S. Pandya, C Tucker,
“Multi-Walled Carbon Nanotude Filled With
Conductive Elastomers: Materials and Application To
Micro Transducers”, MEMS 2006 Conference, Istanbul,
Turkey, January 22 - 26, 2006
[4] K. Ryu, X. Wang, K. Shaikh, and C. Liu, "A method for
precision patterning of silicone elastomer and its
applications," Journal of Microelectromechanical
Systems, Vol. 13, pp. 568-575, 2004
[5] Nexus Market Analysis for MEMS and Microsystems
III, 2005 – 2009
[6] Lab-on-Chip and Microfluidics Technologies'
Capability to Reduce Costs and Time-to-Market Drive
Uptake in Drug Development and Clinical Diagnostics,
Frost & Sullivan, July 2007
[7] Think Small!, issue 2, volume 2, July 2007, Wicht
Technologie Consulting

Recent Application and Future Development Scope in MEMS

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