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| Materials | Fabrication techniques | Advantages | Disadvantages | References |
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| Silicon | The deep reactive ion etching process | Excellent biocompatibility and, specifically, mechanical properties are superior to polymers and metals. Also, they have nonductile nature. This technique gives much better resolution and higher aspect ratios. | Silicon microneedles are brittle and might break in insertion into the skin. This technique gives slow etch rates, low choosiness, and channel effects caused by imitated ions | [77, 78] |
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| Stainless steel | Wet-etching photolithography | Stainless steel is characteristically more disinfected and lasts long. Wet-etching photolithography has almost no harm due to its virtuously chemical nature and is highly selective. | Stainless steel has low heat conductivity and can burn skin when heated up. Wet-etching photolithography has temperature sensitivity, poor element control, and high chemical clearance costs. | [79–82] |
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| Polymers | Micromolding technique | Polymers are biocompatible, biodegradable, and water-soluble. Micromolding technique is highly used for microsized objects. | The strength to size ratio of polymer is fewer as compared to metals. Cannot be machined easily and restricted speed is required for machining it. Micromolding technique is of high cost. | [83, 84] |
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| Titanium | Surface micromachining technique or multilayer technique | Titanium is comparatively more durable and biocompatible as compared to silicon. This surface micromachining technique is more robust and reliable. | Titanium is of higher cost than other metals used and is not suitable for mass production. This technique is also of high cost. | [85–87] |
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| Nickel | Electroless plating | Nickel is a corrosion-free and hygienic material and easily recyclable. This technique gives even coating gif nickel and smooth surface microneedles. | Some allergic reaction occurs using nickel material. High-cost technique and suitable only when the coating is involved. | [88, 89] |
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| Silver and copper | Electrochemical etching (the electrochemical etching technique is a low-cost, clean-room-free technique and highly suitable for mass production, and no costly molding or photoresist mask is needed; it is an easily and safely used technique) | Silver is powerful, highly biocompatible, and natural antibiotic material. Silver nanoparticles are highly used in medicines for different treatments. It has ductile nature. Copper material is a biocompatible metal and endogenously exists in the human body. Copper nanoparticles have been used extensively in many medical treatments. | Silver and copper are not toxic materials so they have only minimal risk of infections and can be safely used. | Current study |
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