Enhancing sensing performance of 3D-printed TPU/CB piezoresistive strain sensors through integration of silver ink IDE Articles uri icon

publication date

  • October 2025

issue

  • 116757

volume

  • 393

International Standard Serial Number (ISSN)

  • 0924-4247

Electronic International Standard Serial Number (EISSN)

  • 1873-3069

abstract

  • In recent years, flexible strain sensors have gained prominence in applications such as wearable electronics, soft robotics, and health monitoring. This trend is attributed to advancements in composite materials and 3D printing techniques. In this study, we fabricated a piezoresistive strain sensor using a commercial conductive filament made from thermoplastic polyurethane (TPU) embedded with carbon black (CB) particles through the fused filament fabrication (FFF) method. We then enhanced this TPU/CB strain sensor by adding a silver ink interdigitated electrode (IDE) to its surface using a direct ink writing (DIW) technique and assessed the effects of this modification. The results showed that the TPU/CB and TPU/CB/Ag samples reached a strain greater than 200 % and exhibited an abnormal negative piezoresistive response during stretching. The addition of IDE silver ink improved the sensitivity at 2 % strain for a gauge factor (GF) of −23.78 and decreased the static electrical drift by 5.3 %. It proves an accurate response to small external stimuli and improves electrical stability while preserving the sensor"s intrinsic piezoresistive behavior. The TPU/CB/Ag sensor detected deformations of different magnitudes and frequencies, maintaining stability and durability over 500 cycles. The practical utility of the TPU/CB/Ag sensor was validated through both human motion detection and integration into a soft robotic link. This research provides valuable information on the trade-off between mechanical and electrical performance of functionalized piezoresistive sensors, offering a viable option for optimization.

subjects

  • Materials science and engineering
  • Robotics and Industrial Informatics

keywords

  • 3d printing; piezo resistive strain sensors; thermoplastic polyurethane (tpu); carbon black (cb); interdigitated electrode.