Vapor sensing using polymer/carbon black composites in the percolative conduction regime

Area of Science:

• Materials Science
• Chemical Engineering
• Sensor Technology

Background:

• Chemiresistive sensors are crucial for vapor detection.
• Optimizing sensor performance involves material composition and operating parameters.
• Understanding behavior near the percolation threshold is key for novel sensor design.

Purpose of the Study:

• Investigate chemiresistive vapor sensors operating near the percolation threshold.
• Evaluate the performance of sensors made from insulating polymers and low carbon black (CB) mass fractions (1-12% w/w).
• Compare sensor characteristics with those using higher CB mass fractions.

Main Methods:

• Fabrication of chemiresistors using polymer-composite materials with varying low carbon black (CB) concentrations.
• Characterization of sensor response to different analyte vapor concentrations.
• Analysis of signal-to-noise ratio, sensor correlation, repeatability, and response linearity.

Main Results:

• Low-mass-fraction CB sensors exhibit large relative differential resistance changes above threshold vapor concentrations.
• These sensors show better signal/noise and lower inter-sensor correlation at high analyte pressures compared to high-CB sensors.
• Nonlinear responses necessitate complex calibration schemes for accurate analyte quantification and drift compensation.

Conclusions:

• Low-mass-fraction CB sensors provide a complementary approach to higher-mass-fraction sensors.
• Their large signals are suitable for low-precision analog-to-digital readout electronics.
• Trade-offs exist between signal-to-noise improvements and the complexity of signal processing algorithms for nonlinear detectors in sensor arrays.