LDT0-028K TE | Alldatasheet
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SENSOR SOLUTIONS /// LDT0-028K Piezo Vibration Rev 1 9/2015 Page 1 LDT WITH CRIMPS VIBRATION SENSOR/SWITCH SPECIFICATIONS 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 silver 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 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.
FEATURES
Solder Tab Connection Both No Mass & With Mass Versions 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 DIMENSIONS
LDT WITH CRIMPS VIBRATION SENSOR/SWITCH SENSOR SOLUTIONS /// LDT0-028K Piezo Vibration Rev 1 9/2015 Page 2
APPLICATIONS
Vibration Sensing in Washing Machine Low Power Wakeup Switch Low Cost Vibration Sensing Car Alarms Body Movement Security Systems 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. A charge amplifier was used to detect the output signal as vibration from a shaker table was applied (using a charge amplifier allows a very long measurem ent time constant and thus allows the "open-circuit" voltage response to be calculated). Small masses (approximately 0.26g increments) were then added to the tip of the sensor, and the measurement repeated. Results are shown in Tabl e 1 and the overlaid plots in Fig. 1. Without adding mass, the LDT0 shows a resonance around 180 Hz. Add ing mass to the tip reduces the resonance frequency and increases "baseline" sensitivity. TABLE 1: LDT0 as Vibration Sensor (see Fig 1) Added Mass Baseline Sensitivity Sensitivity at Resonance Resonant Frequency +3 Db Frequency 0 50 mV/g 1.4 V/g 180 Hz 90 Hz 1 200 mV/g 4 V/g 90 Hz 45 Hz 2 400 mV/g 8 V/g 60 Hz 30 Hz 3 800 mV/g 16 V/g 40 Hz 20 Hz
LDT WITH CRIMPS VIBRATION SENSOR/SWITCH SENSOR SOLUTIONS /// LDT0-028K Piezo Vibration Rev 1 9/2015 Page 3 Experiment #2 LDT0 as Flexible Switch - using a charge amplifier to obtain "open-circuit" voltage sensitivity, the output was measured for controlled tip deflections applied to the sensor (supported by its crimped contacts as described above). 2 mm deflection was sufficient to generate about 7 V. Voltages above 70V could be generated by bending the tip of the sensor through 90 (see Table 2, Fig. 2). TABLE 2: LDT0 as Flexible Switch (see Fig 2) Tip Deflection Charge Output o/c Voltage Output 2 mm 3.4 nC 7 V 5 mm 7.2 nC 15 V 10 mm 10 - 12 nC 20 - 25 V max (90°) > 30 nC > 70 V Experiment #3 Response - when a source capacitance of around 480 pF is connected to a resistive input load, a high-pass filter characteristic results. Using an electronic noise source to generate broad-band signals, the effect of various load resistances was measured and the -3 dB point of the R-C filter determined (see Table 3, Fig. 3).
LDT WITH CRIMPS VIBRATION SENSOR/SWITCH SENSOR SOLUTIONS /// LDT0-028K Piezo Vibration Rev 1 9/2015 Page 4 TABLE 3: LDT0 Electrical Frequency Response (see Fig 3) (480 pF source capacitance) Load Resistance -3 db Frequency
1 Megohm
10 Megohm
100 Megohm
3.3 Hz 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 ma y be "tuned" to suit specific frequency response requirements (see Table 4, Fig. 4). TABLE 4: LDT0 Clamped at Different Lengths (See Fig. 4) Length Beyond Clamp Resonant Frequency Settling Time (5 cyc) 20 mm (no clamp) 180 Hz 28 msec 16 mm 250 Hz 20 msec 11 mm 500 Hz 10 msec 7 mm 1000 Hz 5 msec
LDT WITH CRIMPS VIBRATION SENSOR/SWITCH SENSOR SOLUTIONS /// LDT0-028K Piezo Vibration Rev 1 9/2015 Page 5
ORDERING INFORMATION
TE.com/sensorsolutions Measurement Specialties, Inc., a TE Connectivity company. Measurement Specialties, TE Connectivity, TE Connectivity (logo) and EVERY CONNECTION COUNTS are trademarks. All other logos, products and/o r company names referred to herein might be trademarks of their respective owners. The information given herein, including drawings, illustrations and schematics which are intended for illustration purposes only, is beli eved to be reliable. However, TE Connectivity makes no warranties as to its accuracy or completeness and disclaims any liability in connection with its use. TE Conn ectivity‘s obligations shall only be as set forth in TE Connectivity‘s Standard Terms and Conditions of Sale for this product and in no cas e will TE Connectivity be liable for any incidental, indirect or consequential damages arising out of the sale, resale, use or misuse of the product. Users of TE Connectivity products should make their own evaluation to determine the suitability of each such product for the specific application. © 2015 TE Connectivity Ltd. family of companies All Rights Reserved. NORTH AMERICA Measurement Specialties, Inc., a TE Connectivity Company
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