Axial linear sensors measure the position of a target which is allowed to rotate about the axis of measurement. This configuration suits applications where the moving part's rotation can not be constrained, such as float level sensors, variable area flow meters and syringe plunger position measurement.
Made with a conventional PCB process, they are durable, compact and tolerant of misalignment between target and sensor, as well as large gaps. The large gaps allow sensor and target to be encapsulated in separate housings.
Axial Sensors are Type 3 (find out more about how sensors are classified and what this means for CTU selection in our FAQ) which use four coils - two of these excite the resonator in the target and all four detect signals coming back from the resonator, to be processed by a CAM312 IC.
The images here show (1) a 78mm Type 3.2 Axial Sensor Assembly, (2) an illustration of a float level sensing application using an air core target design and (3) an Axial Sensor working with a wound ferrite rod style target. Other target designs are possible - see datasheet for options.