Table 2 A summary of materials, resolution, advantages, and limitations of methods used in 3D printing of microrobots
Method | Material | Resolution | Advantages | Limitations | Ref. |
|---|---|---|---|---|---|
Stereolithography (SLA) | Resin including photo-activated monomers—hybrid polymer—epoxides—DC 100 (high accuracy)—DC 500—DL 350/360 (high flexibility)—AB 001—GM 08 (high flexibility)— DM 210–DM 220 | 10 μm | Fine spatial resolution—high quality—good surface quality—good precision | Slow printing rate—limited choice of material—costly | |
Digital light processing (DLP) | Diamond micro particle—epoxides—acrylate-based resin—super CAST—super WAX | 25-100 μm | High printing accuracy—low cost—faster printing compared to SLA—less influenced by oxygen interference as opposed to SLA—low initial vat volume is needed | Limited mechanical properties | |
Continuous liquid interface production (CLIP) | Acrylates—rigid polyurethane (RPU)—flexible polyurethane (EPU) (impact resistant)—elastomeric polyurethane—cyanate ester (CE) | 75 μm | Higher production speed compared to DLP | Low-viscosity resins needed | |
Two/multi-photon polymerization (TPP/MPP) | Acrylates | 100 nm | High spatial resolution | Low printing speed—restricted material choice | |
Laser-induced forward transfer (LIFT) | Metal substances and complexes—hydrogel materials | 10 μm | Fine resolution—wide material choice—capability for printing inks in a wide range of viscosities with embedded particles | Slow fabrication process | |
Selective laser sintering (SLS) | Compact fine powder metals—alloys and limited polymers —PA12—PEEK—titanium (biocompatible)—stainless steel—aluminum—cobalt/chrome—nickel-based alloys | 100–250 μm | Low anisotropy | Rough surfaces—poor reusability of unsintered powder—slow printing—lower mechanical properties due to the porous structure | |
Microextrusion 3D printing | PEG—pluronic acid—nanostructured bioinks—alginate—gelatin | 150 μm | Capability to utilize high viscosity bioink and print with high cell density | Distortion of cell structure is conceivable | |
Inkjet 3D printing | Inks or pastes containing a concentrated dispersion of particles in a liquid | 50–200 μm | Fast printing | Low adhesion between layers | |
Fused deposition modeling (FDM) | Thermoplastic polymers—fiber-reinforced polymers— PLA—ABS—ASA—Nylon 12—PC—PPSF/PPSU—PEI or ULTEM (Biocompatible)—PLA—TPU | 50–200 μm | Low cost—high speed—simplicity | Weak mechanical properties —limited material (thermoplastics)—layer-by-layer finish—rough surface—high temperature during the extrusion process (incompatible for cells) |
