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LDT with Crimps Vibration Sensor/Switch

LDT0-028K Piezo Vibration Rev 1 www.meas-spec.com 10/13/2008

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Piezo Film Sensors

High Sensativity

AC Coupled

Laminated

Robust

The

LDT

028K

is a flexible component

comprising a 28 µm thick piezoelectric PVDF

polymer film with screen-printed Ag-ink

electrodes, laminated to a 0.125 mm polyester

substrate, and fitted with two crimped contacts.

As the piezo film is displaced from the

mechanical neutral axis, bending creates very

high strain within the piezopolymer and therefore

high voltages are generated. When the assembly

is deflected by direct contact, the device acts as

a flexible "switch", and the generated output is

sufficient to trigger MOSFET or CMOS stages

directly. If the assembly is supported by its

contacts and left to vibrate "in free space" (with

the inertia of the clamped/free beam creating

bending stress), the device will behave as an

accelerometer or vibration sensor. Adding mass,

or altering the free length of the element by

clamping, can change the resonant frequency

and sensitivity of the sensor to suit specific

applications. Multi-axis response can be

achieved by positioning the mass off center. The

LDTM-028K is a vibration sensor where the

sensing element comprises a cantilever beam

loaded by an additional mass to offer high

sensitivity at low frequencies.

APPLICATIONS

• Vibration Sensing in Washing Machine

• Low Power Wakeup Switch

• Low Cost Vibration Sensing

• Car Alarms

• Body Movement

• Security Systems

dimensions

FEATURES

• Solder Tab Connection

• Both No Mass & With Mass Version

• Withstands High Impact

• Operating Temperature: 0ºC to 85ºC

• Storage Temperature: -40ºC to 85 ºC

• Higher Temperature Version up to 125 ºC

available on a Custom Basis

Summary of content (4 pages)

PAGE 1
LDT with Crimps Vibration Sensor/Switch Piezo Film Sensors High Sensativity AC Coupled Laminated Robust The LDT0-028K is a flexible component comprising a 28 µm thick piezoelectric PVDF polymer film with screen-printed Ag-ink electrodes, laminated to a 0.125 mm polyester substrate, and fitted with two crimped contacts. As the piezo film is displaced from the mechanical neutral axis, bending creates very high strain within the piezopolymer and therefore high voltages are generated.
PAGE 2
LDT with Crimps Vibration Sensor/Switch examples of properties Four different experiments serve to illustrate the various properties of this simple but versatile component. Experiment #1 LDT0 as Vibration Sensor - with the crimped contacts pushed through a printed-circuit board, the LDT0 was soldered carefully in place to anchor the sensor.
PAGE 3
LDT with Crimps Vibration Sensor/Switch examples of Properties (continued) TABLE 2: LDT0 as Flexible Switch (see Fig 2) Tip Deflection Charge Output o/c Voltage Output 2 mm 3.4 nC 7V 5 mm 7.2 nC 15 V 10 mm 10 - 12 nC 20 - 25 V max (90Ε) > 30 nC > 70 V Experiment #3 LDT0 Electrical Frequency Response when the source capacitance of around 480 pF is connected to a resistive input load, a high-pass filter characteristic results.
PAGE 4
LDT with Crimps Vibration Sensor/Switch Experiment #4 LDT0 Clamped at Different Lengths using simple clamping fixture, the vibration sensitivity was measured (as in (1) above) as the clamp was moved to allow different "free" lengths to vibrate. The sensor may be "tuned" to suit specific frequency response requirements (see Table 4, Fig. 4). TABLE 4: LDT0 Clamped at Different Lengths (See Fig.