Underlying Physics of Conductive Polymer Composites and Force Sensing Resistors (FSRs) under Static Loading...

Area of Science:

• Materials Science and Engineering
• Electrical Engineering
• Polymer Science

Background:

• Conductive polymer composites (CPCs) are widely used in sensors due to their piezoresistive properties.
• Existing models for CPCs often neglect voltage-dependent resistance and stress-dependent tunneling conduction.
• Current models rely on rest-state resistance measurements and assume constant tunneling areas.

Purpose of the Study:

• To develop a comprehensive physical model for the piezoresistive response of conductive polymer composites.
• To incorporate voltage-dependent resistance and stress-dependent tunneling conduction into the model.
• To validate the model by comparing its predictions with experimental data from commercial CPC sensors.

Main Methods:

• Development of a specialized test bench for applying controlled forces to CPC sensors.
• Experimental testing of commercial CPC sensors under varying voltages and applied stresses.
• Derivation of a new model based on quantum tunneling conduction equations, including contact resistance.

Main Results:

• The proposed model accurately predicts sensor current based on sourcing voltage and applied stress.
• The model demonstrates a voltage-dependent behavior for composite resistance.
• A stress-dependent behavior for the tunneling conduction area was successfully incorporated and validated.

Conclusions:

• The developed physical model offers a more accurate and comprehensive understanding of CPC piezoresistivity.
• The model's ability to predict sensor current under varying conditions enhances its practical applicability.
• This work advances the design and application of conductive polymer composite-based sensors.