Table 2 Fabrication techniques for a variety of MNs

1.1.1.

Silicon MNs

Microelectromechanical systems (MEMS) techniques, thin-film deposition on a substrate, chemical vapor deposition on a substrate, Silicon dry-etching process, Isotropic etching, etc.

[17, 18]

Metal MNs

Three-dimensional laser ablation, laser cutting (stainless less), metal electroplating methods (palladium), wet etching photochemical etching (titanium), etc.

[19,20,21]

Ceramic MNs

Ceramic micro molding and sintering lithography, etc.

[5]

2.

Coated MNs

Dipping or spraying, layer-by-layer (LbL) coating techniques

[5]

3.

Hollow MNs

Deep reactive ion etching of silicon, deep X-ray photolithography, wet chemical etching, and microfabrication, Integrated lithographic molding technique, etc.

[5]

4.

Dissolving MNs

Micromolding

[5]

5.

Polymeric MNs

Photolithography, micro molding, casting, hot embossing, injection molding, investment molding, etc.

[5, 22,23,24]