Development of MWCNT/Magnetite Flexible Triboelectric Sensors by Magnetic Patterning

The fabrication of low-electrical-percolation-threshold polymer composites aims to reduce the weight fraction of the conductive nanomaterial necessary to achieve a given level of electrical resistivity of the composite. The present work aimed at preparing composites based on multiwalled carbon nanotubes (MWCNTs) and magnetite particles in a polyurethane (PU) matrix to study the effect on the electrical resistance of electrodes produced under magnetic fields. Composites with 1 wt.% of MWCNT, 1 wt.% of magnetite and combinations of both were prepared and analysed. The hybrid composites combined MWCNTs and magnetite at the weight ratios of 1:1; 1:1/6; 1:1/12; and 1:1/24. The results showed that MWCNTs were responsible for the electrical conductivity of the composites since the composites with 1 wt.% magnetite were non-conductive. Combining magnetite particles with MWCNTs reduces the electrical resistance of the composite. SQUID analysis showed that MWCNTs simultaneously exhibit ferromagnetism and diamagnetism, ferromagnetism being dominant at lower magnetic fields and diamagnetism being dominant at higher fields. Conversely, magnetite particles present a ferromagnetic response much stronger than MWCNTs. Finally, optical microscopy (OM) and X-ray micro computed tomography (micro CT) identified the interaction between particles and their location inside the composite. In conclusion, the combination of magnetite and MWCNTs in a polymer composite allows for the control of the location of these particles using an external magnetic field, decreasing the electrical resistance of the electrodes produced. By adding 1 wt.% of magnetite to 1 wt.% of MWCNT (1:1), the electric resistance of the composites decreased from 9 × 104 to 5 × 103 Ω. This approach significantly improved the reproducibility of the electrode’s fabrication process, enabling the development of a triboelectric sensor using a polyurethane (PU) composite and silicone rubber (SR). Finally, the method’s bearing was demonstrated by developing an automated robotic soft grip with tendon-driven actuation controlled by the triboelectric sensor. The results indicate that magnetic patterning is a versatile and low-cost approach to manufacturing sensors for soft robotics.

[1]  M. Paiva,et al.  Fabrication of Low Electrical Percolation Threshold Multi-Walled Carbon Nanotube Sensors Using Magnetic Patterning , 2023, Applied Sciences.

[2]  G. Zhang,et al.  Progress, Challenges, and Prospects of Soft Robotics for Space Applications , 2022, Adv. Intell. Syst..

[3]  Y. Mezouar,et al.  Large-Area and Low-Cost Force/Tactile Capacitive Sensor for Soft Robotic Applications , 2022, Sensors.

[4]  Tinghai Cheng,et al.  Nondestructive Dimension Sorting by Soft Robotic Grippers Integrated with Triboelectric Sensor. , 2022, ACS nano.

[5]  Kunyang Wang,et al.  Biology and bioinspiration of soft robotics: Actuation, sensing, and system integration , 2021, iScience.

[6]  S. Schwaminger,et al.  The Effect of pH and Viscosity on Magnetophoretic Separation of Iron Oxide Nanoparticles , 2021, Magnetochemistry.

[7]  Silvia Terrile,et al.  Comparison of Different Technologies for Soft Robotics Grippers , 2021, Sensors.

[8]  Jeong-Yun Sun,et al.  Hydrogel soft robotics , 2020, Materials Today Physics.

[9]  Liguo Qin,et al.  Enhanced electrical/dielectrical properties of MWCNT@Fe3O4/polyimide flexible composite film aligned by magnetic field , 2020, Journal of Materials Science: Materials in Electronics.

[10]  Zhong Lin Wang,et al.  Soft robots with self-powered configurational sensing , 2020 .

[11]  Chengkuo Lee,et al.  Triboelectric nanogenerator sensors for soft robotics aiming at digital twin applications , 2020, Nature Communications.

[12]  Lingyu Zhu,et al.  Necklace-like Fe3O4 nanoparticle beads on carbon nanotube threads for microwave absorption and supercapacitors , 2020 .

[13]  Zhou Li,et al.  Nanogenerator-Based Self-Powered Sensors for Wearable and Implantable Electronics , 2020, Research.

[14]  Xiaobo Tan,et al.  Smart Soft Actuators and Grippers Enabled by Self‐Powered Tribo‐Skins , 2020, Advanced Materials Technologies.

[15]  M. Khil,et al.  Comprehensive study of effects of filler length on mechanical, electrical, and thermal properties of multi-walled carbon nanotube/polyamide 6 composites , 2019, Composites Part A: Applied Science and Manufacturing.

[16]  Yeongjun Lee,et al.  Flexible Neuromorphic Electronics for Computing, Soft Robotics, and Neuroprosthetics , 2019, Advanced materials.

[17]  P. Alegaonkar,et al.  Multiwalled Carbon Nanotubes Decorated with Fe3O4 Nanoparticles for Efficacious Doxycycline Delivery , 2018, ACS Applied Nano Materials.

[18]  Massimo Totaro,et al.  Toward Perceptive Soft Robots: Progress and Challenges , 2018, Advanced science.

[19]  D. Floreano,et al.  Soft Robotic Grippers , 2018, Advanced materials.

[20]  M. Zhang,et al.  Fabrication of one dimensional CNTs/Fe3O4@PPy/Pd magnetic composites for the accumulation and electrochemical detection of triclosan , 2018, Journal of Electroanalytical Chemistry.

[21]  Weicheng Jiao,et al.  Improving the mechanical properties of Fe3O4/carbon nanotube reinforced nanocomposites by a low-magnetic-field induced alignment , 2018 .

[22]  B. Baytekin,et al.  The Charging Events in Contact-Separation Electrification , 2018, Scientific Reports.

[23]  Wei Yang,et al.  Low percolation threshold and balanced electrical and mechanical performances in polypropylene/carbon black composites with a continuous segregated structure , 2016 .

[24]  D. Rus,et al.  Design, fabrication and control of soft robots , 2015, Nature.

[25]  Hong Liu,et al.  Fe3O4–MWCNT magnetic nanocomposites as efficient peroxidase mimic catalysts in a Fenton-like reaction for water purification without pH limitation , 2014 .

[26]  M. Arvand,et al.  Magnetic core-shell Fe₃O₄@SiO₂/MWCNT nanocomposite modified carbon paste electrode for amplified electrochemical sensing of uric acid. , 2014, Materials science & engineering. C, Materials for biological applications.

[27]  Maciej Zborowski,et al.  Magnetic cell separation: characterization of magnetophoretic mobility. , 2003, Analytical chemistry.

[28]  S. Kawamura,et al.  Flexible self-powered multifunctional sensor for stiffness-tunable soft robotic gripper by multimaterial 3D printing , 2021 .

[29]  Jennifer C. Case,et al.  Multi-mode strain and curvature sensors for soft robotic applications , 2017 .