Table 1.

Different 3D printing methods relevant to biomedical sensor applications.

Methods*	Principle	Materials	Applications	Advantages	Disadvantages	Manufacturers
Material extrusion (Fused deposition modeling)	Nozzle prints melted filament onto a build platform followed by solidification	Acrylonitrile butadiene styrene (ABS), poly lactic acid (PLA), polycarbonate (PC) polystyrene (PS), polyamide, polyetherimide (PEI) etc.	Immunosensor, Lactate sensor[56,91]	A wide range of materials can be used, faster compared to SLA, resolution ≈ 350 μm[92]	Requires support and parts can have lower strength compared to solid polymers.[93]	Makerbot, Ultimaker Prussa
Material extrusion (Direct ink writing)	Liquid ink is extruded from a nozzle	Ceramic slurry, metal inks, graphene, carbon etc.	Metal electrodes,[71] microvascular networks[69]	Compatible with a variety of materials, including biological inks, can use multiple solidification methods[94]	To achieve small feature, ink formulation or specific process modifications are required[95]	Envision TEC 3D-Bioplotter, RepRap Prusa i3 printer
Vat photopolymerization (Stereolithography)	UV light polymerization	Photoresins, ABS, PC, polyethylene, polypropylene, nanocomposite[96]	Cellular Sensor,[97] DNA sensor,[98] Bone tissue scaffold and biomedical implants.[99]	Simple and scalable process. Ability to pattern multiple resins in same layer with strong interlayer adhesion[100]	Lower mechanical strength compared to bulk polymers, difficulty in removing uncured resins, and can print only straight layers[101]	FabPro, Form2
Vat photopolymerization (Digital light processing)	Digital projector is used to cure photoresins	Photoesins, metal powders, polymers, ceramics	Glucose sensor,[102,103] motion sensor[103]	Faster than SLA, uncured photopolymer can be reused.	Difficulty in printing large structures,[104] and difficulty in controlling precise structural shape[105]	3D PrinterPro, Fast Radius
Vat photopolymerization (Two-photon polymerization)	Two photon absorption and polymerization	Polymers, negative or positive photoresists[106]	Tissue scaffolds,[107] lab-on-CMOS sensor[108]	Sub-100 nm resolution[109]	Requires sophisticated optical circuitry and positioning stage.[51]	TOPTICA Photonics AG, Aerotech
Powder bed fusion (Selective laser sintering)	Laser source used to sinter powder particles	Metal powders, Nylon, Polyamide powders	Biomaterials,[110] pH sensors[75]	Fabrication of large parts,[111] resolution ≈100 μm	Requires more time compared to SLA and FDM, limited accuracy of features below a millimeter, requires post-printing processes, and challenging to control porosity.[112]	Fuse 1, Sintratec
Material Jetting (Inkjet printing)	Extrusion of ink and powder liquid binding	Photo-resins, hydrogels, carbon nanotubes[113]	Bionic ear,[114] Bio-membrane[115]	Drop-on-demand, allows high-throughput cell patterning[116] and reactive ink can be printed without agglomeration[117]	Serial process, constrained by viscosity of solvents[118]	Hsausa, Inkcups, NanoDimension
Material Jetting (Aerosol Jet Printing)	Aerosolized droplets delivered by a carrier gas to deposition nozzle and focused by a sheath gas	Metal nanoparticles, polymers, carbon nanotubes,[119] graphene, MXene	Glucose sensor,[87] Protein microarray[120]	Printing in 3D without support,[52] adoptable to a wide viscosity range,[121] and high resolution of 10μm	Particle size limited to < 500 nm, over-spray[122]	Optomec, Integrated Deposition Solutions (IDS) Inc.

^*Categorization of 3D printing methods according to ASTM Standard F2792–12a^[24]