R-series sensor

 

R-19-AL and R-19-CU sensors are fully shielded, low mass, thin, ribbon-type sensors. They consist of a sensing element constructed of Emfit ferroelectret film and 3 layers of electrodes on polyester films, either aluminum or copper electrodes. Crimped connectors are used for connecting to electrodes. Copper electrodes make it possible also solder wires directly onto them.

 

As an option, we can arrange a shielded cable connected to the sensor. The option comes with a temperature melt and pressed silicone protection cover over the cable/sensor joint.

 

The standard width is 19 mm and the length is 6 meters. Rolls can be cut to make shorter sensors. Upon special order, sensors up to 50 meters long are available. Thickness is 0,4 mm.

 

Uses

Perimeter intrusion detection, security, vehicle counting, weigh-in-motion, machine monitoring, vibration/impact sensing, seismic geophone, hydrophone, etc.

 

Sensor Operation

Operating in a reciprocal fashion, changes in the thickness of the Emfit sensor generate a corresponding charge and hence, the voltage appears on the electrodes. The transducer behaves like an active capacitor, consequently, the 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 to its non-resonate behavior. 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 frequent 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 behavior 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.