Design Engineering Magazine - APPLICATIONS

Common Sense.
From an article by Matthew Peach, printed in Design Engineering
12th December 2005

Sensors are now found in a wide range of applications, from
tiny consumer gadgets to spacecraft. But the industry is still
growing - and some markets are expanding fast.

ALTHOUGH SENSORS have been on the increase in industry, the
home, the office and practically all types of consumer products over
the past 50 years, they are showing no signs of saturating their
markets. Indeed, as the technologies improve, costs fall and the
need to sense and measure grows, they are finding ever-more

The parameters that various types of sensors have been detecting
include an alphabet of variables, such as acceleration, chemicals,
electrical, flow, force, humidity, torque, vibration and vision.

Since the beginnings of 'electrical measurement of non-electrical
parameters' in the late 1950s, the quality of a measuring system
has depended mostly on the skills of the manufacturers, who combine
precision mechanics with electrical signal sensors.

This is how systems such as a bourdon tube connected to a
potentiometer enabled electrical measurement of the 'non-electrical'
pressure level. Sensor products were structured so that all components
of the measuring chain were stand-alone 'black boxes' connected in series.

Semiconductors have been used for sensor applications since the
mid-1960s, and system integration was advancing at the same time,
proving to be the domain of small firms which had previously specialised
in precision mechanics.

Smart sensors used for vision
and position use microcontrollers
to add intelligence and functionality
making for a simpler, more intuitive

If the optimisation of semiconductor technology was a first revolutionary
step, the second was more evolutionary. It was brought about by the
miniaturisation of measuring systems - enabling chemical process
analysis to 'wander' out of the laboratory into the chemical plant, and
thus become on-line-capable.

There are four main technical changes influencing developments:
onboard intelligence, semiconductor developments, miniaturisation
and sensor bus technologies to enable attachment to distributed
networks, such as in plants or factories.

Smart sensors using microcontrollers are adding intelligence and
functionality to established sensor technologies for a simpler, more
intuitive set-up. Depending on the sensor type, some or all of the four
innovations are driving sensor markets into adopting the new
technologies, such as smart sensor capabilities, wireless
communications, microelectromechanical systems (MEMS)-based
components, and plug-and-play sensors, with increased precision.

For communications applications, hard.wired network communication
is likely to continue - until and unless wireless control of critical
processes is permitted by health and safety legislation - to be an
important factor in the industrial sensor market.

However, sensors designed for wireless data gathering and condition
monitoring are beginning to come on to the industrial scene. For systems
suppliers such as Invensys the current state of affairs is good news
as they can sell both wired and wireless solutions to their industrial

Certain relatively simple sensing devices, such as discrete output
or analogue output industrial proximity/position sensors have not
generally justified investment in integrated bus connectivity hardware,
but this is changing as integrated circuit prices and cost per node
of controllers fall. Otherwise, 'concentrator' blocks remain the
economical alternative for networking simple sensors to buses.

Though wireless communication is available for industrial use, it
hasn't exactly 'arrived.' Currently, Bluetooth and ZigBee technologies
are the primary contenders. ZigBee standard is a good choice for
low bandwidth, low-power applications. Bluetooth, like ZigBee, opens
up the possibility of cost-effective, efficient, wireless sensors where
data bandwidth and range are more important.

The potential wireless market has led to development in low-power
electronics and high-density, low-cost, and safe energy storage
devices, as the high power consumption of current sensor designs
remains a critical impediment to long-term, cost-effective operation.

Packaging designs are also evolving to address speciality applications,
environmental concerns, and to increase their operating life.
Commonly-used materials, such as plastic, stainless steel, and plate
metal, are expected to evolve with UV-rated plastics for outdoor use,
and FDA-approved materials for use in food and beverage applications,
as well as higher grade stainless steels from 304 to 316. IEC enclosure
ratings are becoming universally recognised, and new ones are being
added to address the need for improved sealing characteristics.

According to Randy Ray, chief design engineer at Hyde Park Electronics
LLC/Schneider Electric, a revolution in miniaturisation is underway.
'MEMS are now widely used in pressure sensors and are likely to be
applied to other industrial sensor technologies, such as ultrasonic and
capacitive proximity/position, force, chemical, and inertial sensors,' he
said. 'The maturing of MEMS fabrication and packaging technology will
lead to low-cost, miniature smart sensors with additional capability at
lower costs.'

The industrial sensors market remains strong
as competition and technical development push
functionality higher and prices lower, so justifying
their use in previously unmonitored machinery
and processes.

One of the main new developments in sensor
technology is the growth of optical techniques,
based on analysis of a sample using refraction,
diffraction or run-time measuring in the UV or
IR range, visible light as well as ultrasound

A recent survey reports that growth in demand for photoelectric and
photo-interrupter sensors wifi be the largest contributor to the overall
growth in the north American proximity and photoelectric sensor market.
Venture Development Corp forecasts a compound annual growth rate
of 5.8 per cent for the two sensor types to 2007, Markets for
photoelectric and photointerrupter sensors comprise 41 per cent of
the $617m (£360m) market, the largest share of the overall 2004
north American proximity and photoelectric sensor market.

Typically, photoelectric sensors are deployed in materials handling,
packaging equipment, and electronics/ semiconductor manufacturing
equipment applications. Office automation equipment applications
account for nearly half the shipments of the photointerrupter sensors.

Factors influencing this growth in demand, particularly in food and
beverage, medical equipment, and office automation equipment
markets, include requirements for non-contact detection, long life,
high-reliability, high-precision, high-speed response, and sub-miniature

One indication of the importance of the sensor market and its booming
business is the growth of the sector's industrial exhibitions. As with
so many areas of industry and technology, the European trade show
heartland in is Germany, where a merger between two sensor shows
is set for next year.

MeasComp and Sensor+Test will unite as The Measurement Fair
and be held annually at the Nuremberg exhibition centre. 'MeasComp
was the best-known platform for professional measuring technology
and attracted an international response. The merger will make this
the world's biggest trade fair for industrial sensors, test and
measurement, including components, technologies and services,'
said Klaus Jansen, MeasComp organiser. Another big sensor-related
show, Vision, will head to the iarger site or tne new Stuttgart Fair.

In the UK the annual exhibition dedicated wholly to sensors, measurement
and instrumentation is the MTEC Show, running for two days, the 15th and
16th February 2006 in Hall 11 at the National Exhibition Centre (NEC) in
Birmingham .


From an article written by Matthew Peach in 'Design Engoneering',
now part of 'The Engineer'.

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