Acellent Technologies, Inc. is developing novel sensor networking
techniques for monitoring the integrity of composite and metal
structures.
Acellent's patented SMART Layer® is a thin dielectric
film with an embedded network of distributed piezoelectric
actuators/sensors. The layer can also incorporate other types
of sensors to monitor properties such as strain and moisture.
The monitoring layer can either be surface-mounted on existing
structures or integrated into composite structures during
fabrication thereby providing a built-in nondestructive assessment
of the internal and external states of the structure.
For a complete list of the sensors,
cables and accessories, download the
Acellent Sensor Catalog
Standard Single Sensor SMART Layers are available as
the off-the-shelf products and are generally in stock.
The SMART Layer strips come with
standard low voltage temperature sensors integrated with the layer itself.
Customized temperature sensors can also be integrated into the
layer depending on the requirements.
Specifications of temperature sensor
- Low voltage operation (2.7V - 5.5V)
- Calibrated directly in oC
- 10mV/C scale factor
- +/- 2C accuracy over temperature
- +/- 0.5C linearity
- Specified -40C to 125C, operation to
150C
- Less than 50 uA quiescent current
- Shutdown current 0.5uA max
- Low self-heating
Different piezoelectric transducers
including PZTs and piezoelectric single crystals can be used in the layers
as well as different connectors.
Additionally, various other types of
sensors can be included in the SMART Layers for ease of installations.
These include strain gages, fiber-optic (Fabry-perot, Bragg grating etc.)
and MEMS.
General Description:
Acellent’s
patented SMART Layer is a thin dielectric film with an embedded network of
distributed piezoelectric actuators/sensors. The layer can also incorporate
other types of sensors including strain and moisture sensors. The layer can
be surface-mounted on structures or integrated into composite structures
during fabrication.
Sensor:
PZT (Lead
Zirconate Titanate) disc, diameter= 6.35 mm (0.25"), thickness=0.254 mm (10
mil), Relative Dielectric Constant=1750, Piezoelectric Coefficient –d31=
175×10-12 m/V, -g31=12.4×10-3
m2/C.
Dielectric Materials :
Polyimide (Pyralux LF materials).
Maximum Input:
50~70 VAC, VDC
~2×.
Strain Range:
- 0.8% to +
0.11%.
Temperature Range:
-40 °F to +221 °F
(-40
°C to +105 °C) for continuous operation; Useful up to +400 °F
(+204
°C) for short term exposure.
Fatigue Life:
No
degradation of
PZT sensor performance is found after 106
cycles
at mechanical fatigue load of maximum strain ε<0.1%, and/or 50 V burst wave
for a wide range of frequency.
Stability:
Aging rate of
piezoelectric ceramic: K (dielectric constant) ~1.5%/decade, f (frequency)
~0.2% ± 0.15%/decade, k (planer coupling factor) ~0.25% ± 0.15%/decade.
Environment:
A protective
coating or encapsulation is recommended if used in a high humidity
aggressive or chemical environment environment.
Thickness of Layer:
Layer thickness
without PZT~7 mil (0.18 mm), while layer thickness with PZT~15 mil (0.38
mm).
Bonding Agents:
For best
performance over the entire temperature range, high temperature epoxy
adhesives are recommended for bonding the layer on the existing structure.
Refer to ASI-001 for installation procedures.
EMI Shielding:
Single side
shielding layer.
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