Direct-Write Deposition of Thermogels

Additive, direct-write manufacturing via a focused electron beam has evolved into a reliable 3D nanoprinting technology in recent years. Aside from low demands on substrate materials and surface morphologies, this technology allows the fabrication of freestanding, 3D architectures with feature sizes down to the sub-20 nm range. While indispensably needed for some concepts (e.g., 3D nano-plasmonics), the final applications can also be limited due to low mechanical rigidity, and thermal- or electric conductivities. To optimize these properties, without changing the overall 3D architecture, a controlled method for tuning individual branch diameters is desirable. Following this motivation, here, we introduce on-purpose beam blurring for controlled upward scaling and study the behavior at different inclination angles. The study reveals a massive boost in growth efficiencies up to a factor of five and the strong delay of unwanted proximal growth. In doing so, this work expands the design flexibility of this technology.

Download Full-text

Spin-wave eigenmodes in direct-write 3D nanovolcanoes

Applied Physics Letters ◽

10.1063/5.0044325 ◽

2021 ◽

Vol 118 (13) ◽

pp. 132405

Author(s):

O. V. Dobrovolskiy ◽

N. R. Vovk ◽

A. V. Bondarenko ◽

S. A. Bunyaev ◽

S. Lamb-Camarena ◽

...

Keyword(s):

Spin Wave ◽

Direct Write

Download Full-text

FEBID 3D-Nanoprinting at Low Substrate Temperatures: Pushing the Speed While Keeping the Quality

Nanomaterials ◽

10.3390/nano11061527 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1527

Author(s):

Jakob Hinum-Wagner ◽

David Kuhness ◽

Gerald Kothleitner ◽

Robert Winkler ◽

Harald Plank

Keyword(s):

Volume Growth ◽

Point Of View ◽

High Fidelity ◽

Direct Write ◽

General Picture ◽

3D Space ◽

Design Flexibility ◽

Substrate Temperatures ◽

Very High ◽

Comprehensive Discussion

High-fidelity 3D printing of nanoscale objects is an increasing relevant but challenging task. Among the few fabrication techniques, focused electron beam induced deposition (FEBID) has demonstrated its high potential due to its direct-write character, nanoscale capabilities in 3D space and a very high design flexibility. A limitation, however, is the low fabrication speed, which often restricts 3D-FEBID for the fabrication of single objects. In this study, we approach that challenge by reducing the substrate temperatures with a homemade Peltier stage and investigate the effects on Pt based 3D deposits in a temperature range of 5–30 °C. The findings reveal a volume growth rate boost up to a factor of 5.6, while the shape fidelity in 3D space is maintained. From a materials point of view, the internal nanogranular composition is practically unaffected down to 10 °C, followed by a slight grain size increase for even lower temperatures. The study is complemented by a comprehensive discussion about the growth mechanism for a more general picture. The combined findings demonstrate that FEBID on low substrate temperatures is not only much faster, but practically free of drawbacks during high fidelity 3D nanofabrication.

Download Full-text

3D printing of spent coffee ground derived biochar reinforced epoxy composites

Journal of Composite Materials ◽

10.1177/00219983211002237 ◽

2021 ◽

pp. 002199832110022

Author(s):

Ahmed Alhelal ◽

Zaheeruddin Mohammed ◽

Shaik Jeelani ◽

Vijaya K Rangari

Keyword(s):

3D Printing ◽

Flexural Modulus ◽

Flexural Properties ◽

Direct Write ◽

Thermal And Mechanical Properties ◽

Spent Coffee Grounds ◽

Coffee Grounds ◽

Spent Coffee Ground ◽

Coffee Ground ◽

3D Printed

Semi-crystalline carbon biochar is derived from spent coffee grounds (SCG) by a controlled pyrolysis process at high temperature/pressure conditions. Obtained biochar is characterized using XRD, SEM, and TEM techniques. Biochar particles are in the micrometer range with nanostructured morphologies. The SCG biochar thus produced is used as reinforcement in epoxy resin to 3 D print samples using the direct-write (DW) method with 1 and 3 wt. % loadings. Rheology results show that the addition of biochar makes resin viscous, enabling it to be stable soon after print; however, it could also lead to clogging of resin in printer head. The printed samples are characterized for chemical, thermal and mechanical properties using FTIR, TGA, DMA and flexure tests. Storage modulus improved with 1 wt. % biochar addition up to 27.5% and flexural modulus and strength increased up to 55.55% and 43.30% respectively. However, with higher loading of 3 wt. % both viscoelastic and flexural properties of 3D printed samples drastically reduced thus undermining the feasibility of 3D printing biochar reinforced epoxies at higher loadings.

Download Full-text