Researchers have developed a groundbreaking 3D-printed pressure sensor that exhibits an anisotropic piezoresistive response, meaning its electrical resistance changes differently depending on the direction of the applied pressure. This innovative sensor, made from a nanocomposite of ABS polymer and carbon nanotubes (CNTs), could revolutionize the field of pressure sensing and have far-reaching applications in robotics, wearable technology, and industrial monitoring.
Harnessing the Power of Nanocomposites
Nanomaterials, such as carbon nanotubes, have unique properties that make them highly attractive for sensing applications. Their high surface-to-volume ratio and the prevalence of quantum effects often lead to superior performance compared to their bulk counterparts. However, for practical and scalable applications, it is often more convenient to use these nanomaterials in the form of nanocomposites, where they are incorporated into a matrix material, such as polymers, metals, or ceramics.
Developing a Novel 3D-Printed Pressure Sensor
In this groundbreaking research, a team of scientists has developed a 3D-printed pressure sensor that capitalizes on the exceptional properties of carbon nanotubes and the versatility of ABS polymer. By depositing a solution of acetone, dimethylformamide, and carboxylic acid-functionalized CNTs onto an ABS substrate using an aerograph, the researchers were able to create a nanostructured, piezoresistive film.
The key innovation lies in the anisotropic piezoresistive response of the material, which means that its electrical resistance changes differently depending on the direction of the applied pressure. This behavior is attributed to the orientation of the printing lines during the 3D printing process, which can either facilitate or hinder the formation of conductive pathways within the nanocomposite.
Unraveling the Secrets of the Nanocomposite
The researchers used advanced characterization techniques to gain a deeper understanding of the material’s structure and properties. Field Emission Gun-Scanning Electron Microscopy (FEG-SEM) revealed the random entanglement of nanotubes on the parallel and perpendicular 3D-printed ABS substrates, as well as the nanostructured film spreading after multiple layers of CNTs deposition.
Fig. 2
Moreover, Raman spectroscopy analysis indicated that the CNTs in the nanocomposite are subjected to compression and p-type doping due to their interaction with the ABS polymer. This electronic interaction between the nanotubes and the polymer matrix is believed to contribute to the observed piezoresistive behavior.
Unlocking the Potential of Anisotropic Piezoresistivity
The anisotropic piezoresistive response of the 3D-printed sensor offers exciting possibilities for various applications. By controlling the orientation of the printing lines and the application of an electric field during the fabrication process, the researchers were able to tailor the electrical resistance and sensitivity of the sensor. This could enable the development of devices capable of distinguishing the direction of mechanical stress, which could be particularly useful in robotic haptic feedback systems, wearable motion monitors, and industrial monitoring applications.
Fig. 3
The researchers report that the best-performing sensing elements, with parallel printing lines and an applied electric field during preparation, exhibited a maximum sensitivity of 0.75 ± 0.36% at the upper operational range of 363.25 ± 0.39 kPa. This was achieved with a relatively low mass percentage of CNTs (0.22 ± 0.30%), demonstrating the efficiency of the 3D printing approach.
Towards a Practical and Scalable Solution
The simplicity and scalability of the 3D printing method used in this study make it a promising candidate for industrial-scale production of pressure sensors. Unlike some other CNT-based piezoresistive nanocomposites that require higher nanoparticle concentrations and more complex preparation methods, this approach offers a more cost-effective and practical solution.
Fig. 4
Furthermore, the researchers suggest that the use of more elastic polymers, such as thermoplastic polyurethane (TPU), could potentially lead to even higher sensitivity and a broader operational range for the pressure sensors.
Paving the Way for the Future
This groundbreaking research has demonstrated the remarkable potential of 3D-printed ABS/CNT nanocomposites for pressure sensing applications. The ability to control the anisotropic piezoresistive response through the printing process opens up new possibilities for the development of advanced, customizable pressure sensors. As the researchers continue to explore this technology, we can expect to see even more innovative solutions that leverage the unique properties of nanomaterials and the versatility of additive manufacturing.
Author credit: This article is based on research by Luciano J. B. Quaresma, Dhonata S. C. Oliveira, Rosielem S. Dias, Kelly C. Alves, Luiz G. D. de Barros, Gustavo Pessin, Amilton Sinatora, Waldeci Paraguassu, Marcos A. L. dos Reis.
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