Printing Carbon Nanotube-Embedded Silicone Elastomers via Direct Writing

Abstract

Direct writing techniques for the printing of colloidal multiwalled carbon nanotubes (CNTs) embedded in polydimethylsiloxane (PDMS) were developed herein to fabricate complex structures including woodpiles, tetragonal scaffolds, and gradient mesh structures. The multiwalled CNTs served as a conductive filler and thickening agent for the printing ink. A suitable rheological behavior was obtained by mixing the CNTs with PDMS dissolved in an isopropyl alcohol solvent. A 7 wt % CNT loading in the PDMS was optimum for printing gap-spanning features at a nozzle moving speed of 20 mm/s. The printed structures, including a woodpile and gradient mesh structure, were capable of detecting changes in external mechanical pressure. Printed CNT/PDMS strips exhibit electrical actuation with good mechanical performance (strain of 8.9%) at a low actuation voltage (60 V). The performance characterization and application display demonstrated the possibility of developing custom complex CNT/PDMS structures for a broad range of applications, including soft robots and flexible electronic devices.

Advancements in Microfabricated Gas Sensors and Microanalytical Tools for the Sensitive and Selective Detection of Odors

“…Despite the good properties of CNTs, they normally come highly entangled by strong van der Waals forces and tend to aggregate, which might compromise their sensing performance [ 171 ]. For this reason, a good dispersion solvent, such as isopropyl alcohol (IPA) or chloroform is generally used for the dispersion of CNTs prior to their implementation [ 172 ]. On the other hand, GR can be produced by chemical or micromechanical exfoliation of graphite, epitaxial growth, or CVD as well [ 155 ].…”

Optimization parameters effects on electrical conductivity of 3D printed circuits fabricated by direct ink writing method using functionalized multiwalled carbon nanotubes and polyvinyl alcohol conductive ink

“…Direct ink writing (D.I.W) method, one of the types of 3D printing technology has attracted researchers in recent years and has been recognised as an advanced fabrication technology because of the wide scope of applications in manufacturing flexible, wearable electronic circuits and components [1][2][3][4][5] e.g., printing flexible circuits [6,7], wearable electronics [8,9], super capacitors [10,11], batteries [12,13], strain sensor [14,15], energy harvesting devices [16,17], touch screens [18,19], bio sensors [20][21][22]. This D.I.W technology advances in the fabrication of complex electronic circuits by adopting pneumatic extrusion process [23][24][25] by formulating ink with controlled rheology [26][27][28].…”

“…Printability of inks is very essential in D.I.W as they determine the performance of fabricated parts. In printed electronics, conductive inks can impart flexibility [4][5][6][7][8]11,32], mechanical robustness and electrical conductivity [15][16][17][18][19]33]. Many researchers have fabricated electronic circuits by D.I.W method with printable inks which are composites of nano fillers like CNT, graphene, carbon black, silver inks and polymers like polyvinyl alcohol (PVA), polydimethylsiloxane (PDMS), polyvinylidene fluoride (PVDF), polyaniline (PANI) [11,14,15,18,22,34,35].…”

“…Abas et al have discussed the fabrication of a very low cost flexible electronic circuit using carbon paste by adopting D.I.W method and observed the conductivity of printed circuits to be 4.26 Â 10 1 S/m [4]. Luo et al demonstrated the feasibility of fabricating CNT/ (PDMS) circuits by D.I.W method with a conductivity of 1.80 Â 10 2 S/m [8]. Electrical conductivity of the graphene based circuits fabricated by Shi et al was observed to be 6 Â 10 2 S/m [14].…”

3D-Printable Carbon Nanotubes-Based Composite for Flexible Piezoresistive Sensors

“…As the electronics market keeps expanding at a high speed, especially with the widespread of the Internet of Things (IoT) with which the use of sensors is expected to reach the trillion by 2023 [2], printed electronics could offer a faster, cheaper and eco-friendlier way to produce electronic devices compared to the traditional manufacturing methods. This field gained tremendous attention in the past decade, largely due to the development and maturity of organic and inorganic nanomaterials (nanowires, nanotubes, nanoparticles,) which can be made into inks/pastes that can be then printed into patterns using different types of printing methods from roll-to-roll, to inkjet and extrusion processes [3][4][5][6][7][8]. The possibility of making polymers into conductive materials by doping certain molecules led to numerous studies working on the development and synthesis of functional flexible materials and nanocomposites using different types of fillers (metallic, ceramic, organic) [9,10].…”