Abstract: A traffic sensor including piezoelectric sensors having different polarities in different lanes of the roadway so that traffic data for different lanes of a roadway may be discriminated from the polarity of the received signal(s). Preferably, the piezoelectric sensors are formed by splicing oppositely polarized piezoelectric cables or films, by changing the applied electric field during manufacture so that adjacent portions of a piezoelectric cable or film have different polarities, or by applying an electric field of a reversed polarity to respective longitudinal sections of a piezoelectric film. Traffic data from up to 8 different lanes of traffic may be discriminated using only two piezoelectric sensors in accordance with the invention by providing unique combinations of output polarities for deflections of the piezoelectric sensors in the different lanes.

Abstract: A method of forming a laminated piezoelectric structure is disclosed wherein a plurality of polarized piezoelectric films of vinylidene fluoride and trifluoroethylene are solvent welded together. The solvent welding solution comprises a copolymer of vinylidene fluoride and trifluoroethylene and a suitable solvent. The transducers produced from such a laminated structure are also disclosed.

Abstract: A penetration sensor is disclosed which contains first and second transducers sandwiched around a layer which capacitively isolates the individual transducers. This sensing arrangement allows for the operational state of the sensor to be tested by applying an interrogation signal to each of the transducers.