Sensor Technik Ltd. - PRODUCT NEWS
     
TTiN thin-film technology marks new step
forward for pressure sensors

Sensor-Technik UK is launching a new series of pressure
sensors featuring what is claimed to be a breakthrough in
technology.

The company's TiN (titanium nitride) thin film coating sensors
are particularly compact, and the precision and long-term
stability specifications are similarly impressive.

The patented design is the result of two years' development
at German manufacturer KMW, following research by
Prof. Mueller at Hamburg Technical University. The diaphragm,
in the form of a capsule, is welded onto the mechanical port
without the use of any sealing materials, giving a totally sealed
(water/air-tight) connection.

By including integrated temperature compensation on the
diaphragm, the need for external electronics is brought to
a minimum (simplified). This also allows the temperature
compensation to take much faster effect as it is mounted with
the strain gauges.

The design offers advantages over piezoresistive sensors,
where the capsule diameter is relatively bigger, and over
ceramic diaphragms, which are slightly higher in cost and
need other sealing materials, which can affect the stability
significantly.

There are other thin-film pressure capsules on the market,
but with nickel-chrome, for example, if the pressure sensors
are subjected to high temperatures, the nickel-chrome-film
is relatively quickly pushed to its limits. Compensating for this
brings problems, notably high cost and loss of long-term stability.

TiN-thin-film can go direct onto the media, and the long-term
stability is high as the film is manufactured directly on to the
sensor material.

TiN thin-film technology has already been tested for more than
1000million cycles on large diesel/gas engines. The gas
temperature during startup is over 1000C. The temperature
effect on the TiN-thin-film pressure capsule is under 1% per
100C; the resistance is controlled, so that the temperature
influence is quickly compensated.

Although earlier types of thin-film pressure measurement
technology are now used widely, the foil strain gauge still
dominates the market due to its low cost and availability.
TiN-thin-film's initial cost is higher, so its advantages are
greater at quantities. However, there are benefits even for 
the small user - and there are more to come. A foil sensor is
being developed which can be welded directly on to the carrier.
A conventional foil strain gauge is glued on, and has problems
with the different ageing process in the different materials
(the foil strain gauge has different ageing to the glue, which
has different ageing to the sensor-material). After a time, the
glue can dissolve: as the pressure is applied to the strain
gauge, the glue lifts. TiN-thin-film technology does not have
these problems.

With the TiN-thin-film technique there is no glue used, and the
film is bonded directly onto the sensor material, giving
durability and safety.
 
Protective layers may be selected depending on environmental
conditions and customer specification; output signal is
compensated internally.
_____________________________________________________

For more information, please contact :-
	
Sensor-Technik Ltd.
Tel: +44(0)1234 823878

August 2001 
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