SELECTION / DEFINE THE CONDITIONS
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How to Select an FSR Flexible Pressure Sensor
Describe how the load is applied before deciding on the sensing film.
FSR selection must consider the detection task, mechanical loading and readout together. Provide contact materials and area, support, preload, target load and duration. Compare prototypes using consistent mechanical, electronic and test conditions.
Define what you need to detect
- Contact or threshold
- Define the presence or threshold state and its decision conditions.
- Relative force
- Compare changes under the same mounting conditions and specify the operating cases.
- Multiple positions
- List positions, area divisions and channels before defining placement and readout electronics.
Include the mechanical assembly in the requirements
The film receives the load transmitted through the assembly. Covers, foam, support, loading heads and assembly preload can all affect the output and must be considered when evaluating samples.
- Mark the outline and effective sensing area.
- Specify contact materials, contact area and rear support.
- Provide the fixing method, tail exit and available bend space.
Specify load, units and time
Force is commonly expressed in N; pressure in Pa. Their relationship depends on contact area. Do not directly compare results with different units, areas or structures.
- Minimum and maximum target load, loading speed, hold time and repetition frequency.
- Operating temperature, humidity, mechanical environment and conditions needing separate validation.
- Existing readout, supply and sampling conditions. Distinguish relative change from absolute measurement.
Make the first selection discussion useful
Send the application, assembly drawing, loading conditions and existing circuit together. Mark unknowns for review. Range, thickness, accuracy and life must be established for specific samples under agreed tests.
Three common selection questions
Are FSRs and flexible-film pressure sensors the same thing?
FSR means force sensing resistor, generally a sensing element whose resistance changes under contact force. Flexible-film pressure sensor is a broader description. Check the sensing principle, mounting method and output rather than assuming identical structure or performance from the name.
Should the target load be in N, Pa or kg?
N measures force, Pa measures pressure and kg measures mass. Specify the load unit and contact area. Conversion between force and pressure needs a defined loaded area and distribution. Total product or body mass is not the load on each sensing point.
Can an FSR be used directly as a scale load cell?
Separate contact detection and relative force change from absolute weight measurement. Weighing or traceable metrology requires defined accuracy, sustained loading, mounting and calibration. Compare sensing principles and the complete system rather than selecting by film shape.