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Table 2 Fabrication techniques of nanoneedles

From: A Review of Nano/Micro/Milli Needles Fabrications for Biomedical Engineering

Methods Fabrication illustrations SEM images Materials Advantages Typical limitations Typical applications
Bottom-up
 Chemical vapor deposition View full size image Solid nanoneedles
Silicon, Carbon, GaN High efficiency, high repeatability Expensive equipment, high production cost Cell sensing, cell drug delivery
 Atom layer deposition View full size image Hollow nanoneedles
Ni
Al2O3
High machining accuracy, high aspect ratio, fit for hollow nanoneedle Expensive equipment, multiple steps, low efficiency Gene delivery, protein extraction
Top-down
 Metal-assisted chemical etch View full size image Porous nanoneedles
Silicon High efficiency, simple process, low cost, fit for mass production Random distribution, wide dimension Cell drug delivery, cell sensing
 Reactive ion etch View full size image Hollow nanoneedles
Silicon
SiO2/Si
High machining accuracy, highly ordered, better controllability Expensive equipment, high resolution mask, low flexible Cell drug delivery
 Focused ion beam View full size image Hollow nanoneedles
View full size image
Silicon Good flexibility, high aspect ratio, fine controllability, fit for hollow nanoneedle Expensive equipment, low efficiency Cell drug delivery, cell sensing
 Nanoimprinting View full size image Solid nanoneedles
View full size image
Aluminum High resolution, low cost, high consistency, fit for mass production Multiple steps, low flexible, high precision mold Biosensing