L-series sensor

L-series sensor is a fully shielded, low mass, thin, large surface sensor. It consists of a sensing element constructed of Emfit ferroelectret film and 3 layers of polyester film with etched aluminum electrodes. Crimped connectors are used for connecting to electrodes. Options available are a shielded cable soldered to connectors with temperature pressed and melt protection cover over the joint and 90 microns acrylic adhesive on one or both sides of the element.

We manufacture L-series sensors in custom shapes and sizes for high volume production. Reel width is 580 mm. For testing our standard lengths available start at 300 mm with 300 mm increments up to 50 meters. Standard widths available are 290 mm and 580 mm.


Safety mats, switches, security, vehicle and pedestrian counting, weigh-in-motion, force plate, machine monitoring, vibration/impact sensing, pyrometer, rain intensity, hail detection, seismic geo-phone, hydrophone, etc.

Sensor Operation

Operating in a reciprocal fashion, changes in the thickness of the Emfit sensor generate a corresponding charge and hence, voltage to appear on the electrodes. The transducer behaves like an active capacitor, consequently, loading of the signal by the input impedance of the measuring device must be considered. Due to the thinness of the films, the associated capacitance can be sufficient to give adequate low frequency response into standard 1 MΩ loads, but the use of an X10 probe will extend the low frequency range by a decade.

For extremely low force change levels, some buffering may be desirable. For the majority of analysis work, this is unnecessary and the film can feed directly to the instrument. Again, the low mass contributed by the transducer is of major importance, and its non-resonate behaviour. Frequency response is inherently flat to over 20 KHz with only the R-C roll off at low frequencies distorting the profile.

Though it is responding to thickness change rather than strain, low signal levels may be generated by low frequency flexing, so a distinction must be made between the frequency response of the film for changes in its primary parameter (i.e., thickness) and its relative behaviour compared with, say piezoelectric sensors. The sensor has a flat response over a very wide frequency range, with resonant frequency points well above 20 KHz.


Property Symbol Value Unit Tolerance Conditions
Storage temperature Ts from -40 to +50 °C
Operating temperature ¹ Tr from -20 to +70 °C
Thickness D 0,4 mm ±5%
Sensitivity Sq 25 pC/N ±20% normal force
Relative permittivity er 1,1 ±10% @ 10 kHz
Capacitance C 22 pF/cm² ±5% @ 1-150 kHz, EQV
Tensile strength at break, TD 535 N ±10% ISO-527-1
Elongation at break, TD 20 % ±20%
Youngs modulus, TD 1,0 MPa ±50%
Operating force range P < 300 N/cm²
Standard width W 290 / 580 mm ±1%
Sample length ² L 3 m ±1%

1) Loss of sensitivity is < 20% after the following temperature cycles:
    a) 11 hours at -20°C, 1 hour at +20°C, 11 hours at +70°C, 1 hour at +20°C, 28 cycles;
    b) 1 hour at -20°C, 1 hour at +70°C, 10 cycles.
2) Manufactured in rolls, width 580 mm, divided into rectangular areas with size of 290 x 300 mm, which are electrically connected to each other. Can be cut to shorter sensors.