3D-fractal engineering based on oxide-only corner lithography

Berenschot, J.W.; Tiggelaar, Roald M.; Geerlings, J.; Gardeniers, Han; Tas, Niels Roelof; Malankowska, Magdalena; Pina, M.P.; Mallada, Reyes

doi:10.1109/dtip.2016.7514895

Cited by 10 publications

(23 citation statements)

References 9 publications

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“…However, a non-random quasi-exact fractal size distribution could be seen over the smallest and largest octahedral features (Figure S2). Interestingly, relatively high surface-area-to-volume ratios between 1.1 and 1.6 per fractal unit in Figure 1b-e were obtained [46,47]. These units could then be expanded over larger areas forming arrays of defined interspaces (i) and heights (h) over different lattice configurations.…”

Section: Caf Response To Topographic Surfaces Of Increasing Complexitymentioning

confidence: 94%

“…Details on the fabrication process of the topographies in Figure 1 are presented in the supporting information, which can be found in the section named fabrication of the topographical surfaces. A similar fabrication process as described in [46,47] was followed for the planar substrates used as controls. In short, planar substrates involved the growth of SiO 2 over a silicon wafer, which was then bonded to the glass.…”

Section: Topographical Surfacesmentioning

confidence: 99%

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Complex Tumor Spheroid Formation and One-Step Cancer-Associated Fibroblasts Purification from Hepatocellular Carcinoma Tissue Promoted by Inorganic Surface Topography

et al. 2021

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In vitro cell models play important roles as testbeds for toxicity studies, drug development, or as replacements in animal experiments. In particular, complex tumor models such as hepatocellular carcinoma (HCC) are needed to predict drug efficacy and facilitate translation into clinical practice. In this work, topographical features of amorphous silicon dioxide (SiO2) are fabricated and tested for cell culture of primary HCC cells and cell lines. The topographies vary from pyramids to octahedrons to structures named fractals, with increased hierarchy and organized in periodic arrays (square or Hexagonal). The pyramids were found to promote complex 2D/3D tissue formation from primary HCC cells. It was found that the 2D layer was mainly composed of cancer-associated fibroblasts (CAFs), while the 3D spheroids were composed of tumor cells enwrapped by a CAF layer. Compared with conventional protocols for 3D cultures, this novel approach mimics the 2D/3D complexity of the original tumor by invading CAFs and a microtumor. Topographies such as octahedrons and fractals exclude tumor cells and allow one-step isolation of CAFs even directly from tumor tissue of patients as the CAFs migrate into the structured substrate. Cell lines form spheroids within a short time. The presented inorganic topographical surfaces stimulate complex spheroid formation while avoiding additional biological scaffolds and allowing direct visualization on the substrate.

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Section: Caf Response To Topographic Surfaces Of Increasing Complexitymentioning

confidence: 94%

Section: Topographical Surfacesmentioning

confidence: 99%

Complex Tumor Spheroid Formation and One-Step Cancer-Associated Fibroblasts Purification from Hepatocellular Carcinoma Tissue Promoted by Inorganic Surface Topography

et al. 2021

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“…The method of engineering of a 3D-fractal structure is based on a combination of anisotropic etching of silicon and corner lithography [ 17 , 18 ]. Basically, a silicon (Si) wafer with thermally grown SiO 2 was patterned in buffered hydrofluoric acid (BHF) using a resist mask with a regular pattern of holes (25 μm diameter and 25 μm periodicity).…”

Section: Methodsmentioning

confidence: 99%

3D Fractals as SERS Active Platforms: Preparation and Evaluation for Gas Phase Detection of G-Nerve Agents

et al. 2018

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One of the main limitations of the technique surface-enhanced Raman scattering (SERS) for chemical detection relies on the homogeneity, reproducibility and reusability of the substrates. In this work, SERS active platforms based on 3D-fractal microstructures is developed by combining corner lithography and anisotropic wet etching of silicon, to extend the SERS-active area into 3D, with electrostatically driven Au@citrate nanoparticles (NPs) assembly, to ensure homogeneous coating of SERS active NPs over the entire microstructured platforms. Strong SERS intensities are achieved using 3D-fractal structures compared to 2D-planar structures; leading to SERS enhancement factors for R6G superior than those merely predicted by the enlarged area effect. The SERS performance of Au monolayer-over-mirror configuration is demonstrated for the label-free real-time gas phase detection of 1.2 ppmV of dimethyl methylphosphonate (DMMP), a common surrogate of G-nerve agents. Thanks to the hot spot accumulation on the corners and tips of the 3D-fractal microstructures, the main vibrational modes of DMMP are clearly identified underlying the spectral selectivity of the SERS technique. The Raman acquisition conditions for SERS detection in gas phase have to be carefully chosen to avoid photo-thermal effects on the irradiated area.

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“…Oxide-only corner lithography 28 was applied to fabricate the structures shown in the second column of Fig. 7.…”

Section: Fabrication and Visualization Of Repeated 3d Structuresmentioning

confidence: 99%

Wafer-scale 3D shaping of high aspect ratio structures by multistep plasma etching and corner lithography

Berenschot

Westerik

et al. 2020

Microsyst Nanoeng

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The current progress of system miniaturization relies extensively on the development of 3D machining techniques to increase the areal structure density. In this work, a wafer-scale out-of-plane 3D silicon (Si) shaping technology is reported, which combines a multistep plasma etching process with corner lithography. The multistep plasma etching procedure results in high aspect ratio structures with stacked semicircles etched deep into the sidewall and thereby introduces corners with a proper geometry for the subsequent corner lithography. Due to the geometrical contrast between the gaps and sidewall, residues are left only inside the gaps and form an inversion mask inside the semicircles. Using this mask, octahedra and donuts can be etched in a repeated manner into Si over the full wafer area, which demonstrates the potential of this technology for constructing high-density 3D structures with good dimensional control in the bulk of Si wafers.

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3D-fractal engineering based on oxide-only corner lithography

Cited by 10 publications

References 9 publications

Complex Tumor Spheroid Formation and One-Step Cancer-Associated Fibroblasts Purification from Hepatocellular Carcinoma Tissue Promoted by Inorganic Surface Topography

Complex Tumor Spheroid Formation and One-Step Cancer-Associated Fibroblasts Purification from Hepatocellular Carcinoma Tissue Promoted by Inorganic Surface Topography

3D Fractals as SERS Active Platforms: Preparation and Evaluation for Gas Phase Detection of G-Nerve Agents

Wafer-scale 3D shaping of high aspect ratio structures by multistep plasma etching and corner lithography

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