Force and slip detection with direct-write compliant tactile sensors using multi-walled carbon nanotube/polymer composites

• A compliant tactile sensor with flexible conductive wires was fabricated through direct-write (DW) process.
• Multi-walled carbon nanotubes (MWCNTs) were successfully dispersed in a flexible and photocrosslinkable monomer.
• Experiments were performed to show that the sensor could detect applied forces at distinct locations on the surface.
• Slip was detected by examining the frequency content of the signals.
• A Chebyshev band pass filter was developed to amplify these vibrations to distinguish between slip and nonslip contact.

A mechanically compliant tactile sensor has been developed through direct-write (DW) deposition of a flexible conductive nanocomposite embedded between flexible polyurethane materials. Dispersion of multi-walled carbon nanotubes (MWCNTs) in a flexible and photocurable monomer introduced electrical and piezoresistive properties to the polymer which was used for the flexible conductive nanocomposite. Dispensing experiments were performed using the developed DW system to precisely create and embed the sensor elements between polyurethane substrates. From the experimental results, several flexible sensors including highly stretchable sensor elements (wires) were fabricated. Experiments were also performed to show that the sensor could detect applied forces at distinct locations on the surface. Slip was detected by examining the frequency content of the signals; sliding contact was characterized by a greater presence of high frequency power spectral density caused by mechanical vibrations that occur during slip. A Chebyshev band pass filter was developed to amplify these vibrations to distinguish between slip and nonslip tactile events. Finally, it is concluded that the study demonstrated in this work provides compelling evidence that the suggested materials, and methods of fabrication and characterization are promising for compliant tactile sensors.