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Deterministic lateral displacement (DLD) is a microfluidic micro/nanopost array-based technique for size-based particle separations. A key challenge in scaling DLD for handling smaller particles is that creating such “nanoDLD” arrays can be cost-intensive with substantial technical hurdles. To circumvent such issues, here we explore a new “hexagonally arranged triangles (HAT)” DLD geometry that is based on patterns associated with nanosphere lithography (NSL). Finite element simulations and preliminary experiments with 0.86 μm and 4.7 μm particles suggest effective separation capabilities of the HAT-DLD approach, marking an important first step toward new classes of nanoDLD arrays fabricated through bottom-up, self-assembly-based NSL.
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Rapid Quantification of Nanosphere Lithography Packing Defects Using Scanning Electron Microscopy Edge Effects
Nanosphere lithography (NSL) is a bottom‐up, self‐assembly approach that enables rapid, low‐cost patterning of nanoscale features. The practical application and scalability of NSL relies on the ability to achieve defect‐free nanosphere self‐assembly over large substrate areas. Self‐assembly methods for single‐layer nanosphere templates are typically evaluated using scanning electron microscopy (SEM) imaging, with literature reports focusing on maximum area of continuous nanosphere coverage. An alternative performance metric—namely, the percentage of nanospheres exhibiting perfect hexagonal close‐packing (%HCP)—is uniquely critical to NSL precision and repeatability. To enhance current methods of evaluating nanosphere self‐assembly, this work presents an SEM image analysis approach for rapidly quantifying packing defects in single‐layer nanospheres to determine %HCP. The method uses variations in SEM edge effect brightness to distinguish spheres with perfect packing from those in defect configurations or along edges. Comparison of image analysis program results with manual counting of nanospheres indicates that the program has a high degree of accuracy, with a mean error on the %HCP metric of +8.6% (absolute error). The results suggest that the present strategy offers a promising pathway to rapid evaluation of nanosphere self‐assembly for high‐precision NSL applications such as surface‐enhanced Raman scattering, photovoltaic cells, and nanogap electrodes.
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- PAR ID:
- 10260463
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- physica status solidi (RRL) – Rapid Research Letters
- Volume:
- 14
- Issue:
- 11
- ISSN:
- 1862-6254
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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