Transcript Prezentacja programu PowerPoint

Microsystems and sensor networks
Lecturer - prof. Tadeusz Pisarkiewicz
building C-1, room No. 316
e-mail: [email protected]
homepage: http://home.agh.edu.pl/~pisar
Assistants: Wojciech Maziarz, PhD , [email protected]
Łukasz Krzak, MSc, Eng, [email protected]
Textbooks:
1. Nadim Maluf, Kirt Williams, An Introduction to Microelectromechanical
Systems Engineering, Second Edition, Artech House 2004.
2. Jacob Fraden, AIP Handbook of modern sensors: physics, design and
applicattions, AIP New York, 1993.
3. Waltenegus Dargie, Christian Poellabauer, Fundamentals of wireless sensor
networks : theory and practice, Wiley 2010.
Introduction
Definitions of terms used
Sensor - a device that converts a quantity of one kind into a quantity of another
kind (in most cases into an electrical signal)
Lambda sensor for detection of oxygen in exhaust gases of a car
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Definitions of terms used, cont.
Microsensor - a sensor that has at least one physical dimension at the
submillimetre level
The STJ-001 low-field magnetic
microsensor in a die form, with active
area of 1 x 2 microns.
The die is 1.9 mm square and 300 microns thick.
It has four gold wirebonding pads which allow four-point
measurement of the device resistance.
The field sensitivity of the STJ-001 is 5 nT, which is ten
thousand times smaller than the magnetic field of the Earth.
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Definitions of terms used, cont.
Actuator - a device that converts an electrical signal into a nonelectrical
quantity
Electrostatic actuators with applied voltage V which results in an
attractive force:
(a) parallel plate actuator with force normal to the plate surfaces
(b) electrostatic comb actuator with attractive force in the direction of
the interdigitated teeth.
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Definitions of terms used, cont.
MEMS device – Micro-Electro-Mechanical System consisting of microsensors,
actuators and microelectronic circuitry
Examples of MEMS accelerometers: Analog Devices ADXL250 (on the left)
and Motorola dual-structure microsystem before encapsulation (on
5 the right)
1. Evolution of microsensors
The vast increase in microelectronics technology has caused that the price-toperformance ratio of both sensors and actuators had fallen remarkably
behind processors.
Consequently, measurement systems tended to be large and, more importantly,
expensive.
Work therefore started to use the microelectronic technologies to make siliconbased sensors, the so-called microsensors.
World market for ICs and microsensors from 1990 to 2000
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It is evident that the market for microsensors lags well behind the market for ICs.
The main cause has been the relatively stable price-performance (p/p) ratio of
sensors and actuators since 1960, as illustrated in the Figure below.
This contrasts markedly with the p/p ratio
of ICs, which has fallen enormously
between 1960 and 2000 and is now
significantly below that for sensors and
actuators.
As a consequence of these changes, the
cost of a measurement system is, in
general, dominated first by the cost of the
microactuator and second by the cost of
the microsensor.
Price-performance indicators for
ICs, sensors, and actuators
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2. Evolution of MEMS
The miniaturisation of a sensor leads to producing of a microsensor, secondly the
integration of a microsensor and its microelectronic circuitry gives so-called smart
sensor; and thirdly, the integration of a microsensor, a microactuator, and their
microelectronic circuitry produces a microsystem.
Many of the microsystems being fabricated today employ silicon microtechnology
and this technology is commonly referred to as MST (microsystem technology).
Work to achieve this goal started in the late 1980s, and there has been enormous
effort to fabricate microelectromechanical systems (MEMS) using MST.
Elements of a MEMS chip
together with overview of its
technology and applications
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3. Emergence of micromachines
Natural evolution will then lead to MEMS devices that move around by
themselves.
Such chips are commonly referred to as micromachines: microplanes,
microrobots, microcars, microsubmarines.
Micromachines, if developed, will need sophisticated microsensors so that they
can determine their location and orientation in space and proximity to other
objects.
They should also be able to communicate with
a remote operator and hence will require a
wireless communication link - especially if they
are asked to enter the human body.
Dimensions of microsensors, MEMS, and micromachines;
they are compared with some everyday objects.
The horizontal axis has a logarithmic scale.
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