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 |
| Solid nanoneedles
| Silicon, Carbon, GaN | High efficiency, high repeatability | Expensive equipment, high production cost | Cell sensing, cell drug delivery |
Atom layer deposition |
| 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 |
| 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 |
| 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 |
| Hollow nanoneedles
| Silicon | Good flexibility, high aspect ratio, fine controllability, fit for hollow nanoneedle | Expensive equipment, low efficiency | Cell drug delivery, cell sensing |
Nanoimprinting |
| Solid nanoneedles
| Aluminum | High resolution, low cost, high consistency, fit for mass production | Multiple steps, low flexible, high precision mold | Biosensing |
