Strain-engineered manufacturing of freeform carbon nanotube microstructures

Abstract

The skins of many plants and animals have intricate microscale surface features that give rise to properties such as directed water repellency and adhesion, camouflage, and resistance to fouling. However, engineered mimicry of these designs has been restrained by the limited capabilities of top-down fabrication processes. Here we demonstrate a new technique for scalable manufacturing of freeform microstructures via strain-engineered growth of aligned carbon nanotubes (CNTs). Offset patterning of the CNT growth catalyst is used to locally modulate the CNT growth rate. This causes the CNTs to collectively bend during growth, with exceptional uniformity over large areas. The final shape of the curved CNT microstructures can be designed via finite element modeling, and compound catalyst shapes produce microstructures with multidirectional curvature and unusual self-organized patterns. Conformal coating of the CNTs enables tuning of the mechanical properties independently from the microstructure geometry, representing a versatile principle for design and manufacturing of complex microstructured surfaces.

Trihalomethane, dihaloacetonitrile, and total N-nitrosamine precursor adsorption by carbon nanotubes: the importance of surface oxides and pore volume

“…The tunable physicochemical properties of carbon nanotubes (CNTs) 1,2 have the potential to be exploited in drinking water treatment plants (DWTPs) to adsorb organic precursors of disinfection byproducts (DBPs). While CNT toxicity 3,4 is a concern in water treatment, the technology is now available to grow CNTs on various substrates as well as to incorporate CNTs into membrane filtration systems.…”

Vertically Aligned Carbon Nanotubes as Platform for Biomimetically Inspired Mechanical Sensing, Bioactive Surfaces, and Electrical Cell Interfacing

“…The response of VACNTs to external forces or stimuli like flow of liquids, gases, or the detection of sound thus relies on the combination and exact setting of these parameters. Here, the method of strain‐engineered growth represents a valuable technique toward tuning and understanding the properties of VACNTs and generating complex 3D architectures by a bottom‐up growth technique …”

“…Although the Young's modulus of such a VACNT bundle depends on its length and is in the range between 200 and 1600 kPa it is strongly controlled by the extreme buckling effect close to the substrate . This buckling could be further controlled and optimized employing a strain/strength‐related growth process reported earlier by Hart and co‐workers . In that process, different catalyst/substrate layer interactions are employed to manipulate the growth direction and VACNT morphology.…”

Free Form Growth of Carbon Nanotube Microarchitectures on Stainless Steel Controlled via Laser‐Stimulated Catalyst Formation

“…In the strive to accommodate the increasing demand for complex CNT microarchitectures, controlling CNT alignment is of paramount importance. To our knowledge, the only technique capable of implementing this parameter to date is strain engineered chemical vapor deposition . It is based on the lithographic patterning of adjacent catalysts patches promoting different rates of CNT growth and utilizes the strain‐induced bending of entangled CNT bundles growing at divergent rates.…”