MiniSense 100 Vibration Sensor
High Sensitivity
Good Frequency Response
Excellent Linearity
Shielded Construction
Analog Output
Withstands High Shock
The Minisense 100 is a low-cost
cantilever-type vibration sensor loaded by
a mass to offer high sensitivity at low
frequencies. The pins are designed for
easy installation and are solderable.
Horizontal and vertical mounting options
are offered as well as a reduced height
version. The active sensor area is shielded
for improved RFI/EMI rejection. Rugged,
flexible PVDF sensing element withstands
high shock overload. Sensor has excellent
linearity and dynamic range, and may be
used for detecting either continuous
vibration or impacts.
The mass may be modified to obtain
alternative frequency response and
sensitivity selection (consult factory).
APPLICATIONS
Washing Machine Load Imbalance
Vehicle Motion Sensor
Anti-Theft Devices
Vital Signs Monitoring
Tamper Detection
Impact Sensing
Dimensions (in millimeters)
FEATURES
High Voltage Sensitivity (1 V/g)
Over 5 V/g at Resonance
Horizontal or Vertical Mounting
Shielded Construction
Solderable Pins, PCB Mounting
Low Cost
< 1% Linearity
Up to 40 Hz (2,400 rpm) Operation
Below Resonance
MiniSense 100 Vibration Sensor Rev 1 www.meas-spec.com 05/12/2009
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MiniSense 100 Vibration Sensor
MiniSense 100 Vibration Sensor Rev 1 www.meas-spec.com 05/12/2009
performance specifications
Typical properties/specifications
Typical Properties (at 25 °C)
Parameter Value Units
Voltage Sensitivity (open-circuit, baseline) 1.1 V/g
Charge Sensitivity (baseline) 260 pC/g
Resonance Frequency 75 Hz
Voltage Sensitivity (open-circuit, at
resonance)
6 V/g
Upper Limiting Frequency (+3 dB) 42 Hz
Linearity +/-1 %
Capacitance 244 pF
Dissipation Factor 0.018 (none)
Inertial Mass 0.3 gram
Environmental Specifications
Storage Temperature -40 to +80 deg C
Operating Temperature -20 to +60 deg C
Minisense 100H 0.5 gram
Weight Minisense 100V 0.6 gram
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MiniSense 100 Vibration Sensor
MiniSense 100 Vibration Sensor Rev 1 www.meas-spec.com
functional description
Th
e
Mi
n
iS
ense
100
acts as a cantileve
r
-beam accelerometer. When the beam is mounted
horizontally, acceleration in the vertical plane creates bending in the beam, due to the inertia of the
mass at the tip of the beam. Strain in the beam creates a piezoelectric response, which may be
detected as a charge or voltage output across the electrodes of the sensor.
The sensor may be used to detect either continuous or impulsive vibration or impacts. For
excitation frequencies below the resonant frequency of the sensor, the device produces a linear
output governed by the “baseline” sensitivity quoted above. The sensitivity at resonance is
significantly higher. Impacts containing high-frequency components will excite the resonance
frequency, as shown in the plot above (response of the MiniSense 100 to a single half-sine impulse
at 100 Hz, of amplitude 0.9 g). The ability of the sensor to detect low frequency motion is strongly
influenced by the external electrical circuit, as described below (see “Electrical Description”).
electrical description
The MiniSense 100 behaves electrically as an “active” capacitor: it may be modelled as a
perfect voltage source (voltage proportional to applied acceleration) in series with the quoted
device capacitance. Any external input or load resistance will form a high-pass filter, with a roll-off
frequency as tabulated above, or calculated from the formula f(c) = 1/(2πRC). The impedance of
the sensor is approximately 650 M ohm at 1 Hz. The active sensor element is electrically shielded,
although care should be taken in the PCB design to keep unshielded traces as short as possible.
Lower Limiting Frequency (-3 dB roll-off)
External R (Ω) LLF (Hz) Desired LLF (Hz) Required R (Ω)
10 M 65 10 65 M
100 M 6.5 1 650 M
1 G 0.65 0.1 6.5 G
1E+06
1E+07
1E+08
1E+09
1E+10
Impedance (ohms)
0.1 1 10 100
Frequency (Hz)
Electrical Impedance
-40
-30
-20
-10
0
10
Magnitude (dB)
0.1 1 10
Frequency (Hz)
1 G
100 M
Low frequency roll-off
05/12/2009
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MiniSense 100 Vibration Sensor
off-axis sensitivity
-50
-40
-30
-20
-10
0
Sensitivity (dB re nominal)
0 30 60 90 120 150 180
Rotation angle (deg)
axial
theory
vertical
Off-axis Response
The sensitivity of the Minisense 100 follows a cosine law, when rotated horizontally around its axis,
or vertically around its mid-point. At 90 degrees rotation in either plane, both baseline sensitivity and
sensitivity at resonance are at a minimum. In theory, sensitivity should be zero in this condition. It is
likely that some sensitivity around the resonance frequency will still be observed – but this may be
unpredictable and is likely to be at least -16 dB with reference to the on-axis response. Note that the
sensitivity at 30 degrees rotation is -1.25 dB (87% of on-axis response), at 60 degrees, it falls to -6
dB (50%).
The plots below show the change in sensitivity observed for either:
1) Rotation about major axis of sensing element, or
2) Rotation about mid-point of sensing element.
The information in this sheet has been carefully reviewed and is believed to be accurate; however, no responsibility is assumed for inaccuracies. Furthermore, this information does not
convey to the purchaser of such devices any license under the patent rights to the manufacturer. Measurement Specialties, Inc. reserves the right to make changes without further notice
to any product herein. Measurement Specialties, Inc. makes no warranty, representation or guarantee regarding the suitability of its product for any particular purpose, nor does
Measurement Specialties, Inc. assume any liability arising out of the application or use of any product or circuit and specifically disclaims any and all liability, including without limitation
consequential or incidental damages. Typical parameters can and do vary in different applications. All operating parameters must be validated for each customer application by
customer’s technical experts. Measurement Specialties, Inc. does not convey any license under its patent rights nor the rights of others.
ordering information
Description Model No. Part No.
Horizontal Mounting LDTC-H 1005939-1
Vertical Mounting LDTC-V 1005940-1
Horizontal Mounting Reduced Height LDTC-RH 1006015-1
North America
Measurement Specialties, Inc.
1000 Lucas Way
Hampton, VA 23666
Sales and Customer Service
Tel: +1-800-745-8008 or
+1-757-766-1500
Fax: +1-757-766-4297
Technical Support
Email: piezo@meas-spec.com
Europe
MEAS Deutschland GmbH
Hauert 13
44227 Dortmund
Germany
Sales and Customer Service
Tel: +49 (0)231 9740 21
Technical Support
Tel: +49 (0)6074 862822
Email: piezoeurope@meas-spec.com
Asia
Measurement Specialties (China), Ltd.
No. 26 Langshan Road
Shenzhen High-Tech Park (North)
Nanshan District
Shenzhen, China 518107
Sales and Customer Service
Tel: +86 755 3330 5088
Technical Support
Email: piezo@meas-spec.com
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