Three-Dimensional Printed Nanocomposites with Tunable Piezoresistive Response

Area of Science:

• Materials Science and Engineering
• Additive Manufacturing
• Sensor Technology

Background:

• Strain sensors are crucial for monitoring deformation in various applications.
• Developing advanced materials with tailored sensing properties is an ongoing research area.
• 3D printing offers a versatile platform for fabricating customized sensor geometries and functionalities.

Purpose of the Study:

• To investigate the influence of printing parameters on the piezoresistive behavior of carbon nanotube-filled acrylonitrile butadiene styrene (ABS) composites.
• To characterize the morphological and electrical properties of 3D printed strain sensors.
• To develop a 3D printed sensor capable of measuring two-dimensional deformations for robotic applications.

Main Methods:

• Fused filament fabrication (FFF) was used to print dog-bone shaped samples of ABS with varying carbon nanotube (CNT) concentrations.
• Two raster angles (0° and 90°) were employed during the FFF process.
• Scanning electron microscopy (SEM), atomic force microscopy (AFM) in TUNA mode, and tensile tests were conducted for material characterization and performance evaluation.
• Creep, fatigue, and two-dimensional deformation tests were performed to assess sensor durability and functionality.

Main Results:

• Piezoresistive sensitivity, quantified by the gauge factor (G.F.), decreased with increasing CNT filler content for both raster angles.
• The 90° raster angle consistently yielded higher sensitivity compared to the 0° raster angle at identical filler concentrations.
• Creep and fatigue testing revealed permanent damage indicated by residual electrical resistance.
• A novel cross-shaped sensor design successfully measured simultaneous two-dimensional deformations by monitoring resistance changes in its arms.

Conclusions:

• Printing conditions, particularly raster angle, significantly affect the piezoresistive performance of CNT-filled ABS strain sensors.
• The 90° raster orientation offers enhanced sensitivity for strain sensing applications.
• The developed 3D printed sensor demonstrates potential for real-time monitoring of complex deformations in robotics and other fields.
• Further research can optimize CNT dispersion and printing strategies for improved sensor performance and durability.