3D Printing Flashcards
What is 3D printing?
also known as additive manufacturing
- process of making three dimensional solid objects from a digital file by printing layer by layer
- produces complex shapes and geometries
How are 3D printed objects developed?
a virtual design of the desired object is made
- it can be created using a computed aided design (CAD) file
a computer software will then slice the 3D module into hundreds/thousands of horizontal layers
- when the 3D model is sliced, it is ready to be fed into the 3D printer
What are the 5 different 3D printing techniques?
stereolithographic 3D printing (SLA)
powder based 3D printing (PB)
selective laser sintering 3D printing (SLS)
fused deposition modelling 3D printing (FDM)
semi solid extrusion 3D printing (EXT)
What is the process of stereolithographic 3D printing (SLA)?
involves the curing (hardening) of photosensitive materials to produce a 3D object
- is based on the photo-polymerisation of a photopolymer ‘resin’ to produce the 3D structure
curing of the polymers is performed using ultraviolet (UV) light
UV light is shone at a digital mirroring device to initiate a chemical reaction in the photopolymer which causes gelation of the exposed area
- follows a predetermined path
What are the advantages and disadvantages of SLA?
stereolithographic 3D printing
advantages
- fast = efficient when it comes to rapid prototyping
- high level of accuracy and resolution
- durable = produces prototypes that can withstand mechanical forces
- widely used in tissue engineering and the fabrication of implantable devices
disadvantages
- expensive
- potential health hazard = resin are toxic
- risk of API decomposition
- lack of FDA approved photosensitive polymers
When is SLA 3D printing used?
when you need to make 3D objects that
- need to withstand mechanical forces
- need to have a high level of accuracy and resolution
- need to be made quickly
What is the process of powder based 3D printing (PB)?
involves the distribution of thin layers of powder via powder bed or powder jetting mechanisms
an inkjet print head moves across a bed of powder, selectively depositing a liquid binding material
a thin layer of powder is spread across the completed section and the powder particles are bound together to form a layer of the desired object
the process is repeated with each layer adhering to the last.
drying step is essential to eradicate any solvent/binder residue
What are the advantages and disadvantages of PB?
powder based 3D printing
advantages
- shows precise location of exact dose of drug or modifying excipients within powdered bed to obtain several compartments with different composition of MOA
- similar to classical formulation processes (wet granulation)
- can use excipients commonly used in pharmaceutical field
disadvantages
- poor mechanical resistance
- high friability (increased tendency to crumble/break)
- achieving high resolution objects can be challenging (depends on nozzle size)
- nozzle clogging can occur
When is PB 3D printing used?
when the exact composition of the 3D object needs to be known or when complex objects with different MOAs are needed
when commonly used excipients need to be used
What is the process of selective laser sintering 3D printing (SLS)?
is similar to 3D printing
high energy beam is created usually by laser radiation
- laser beam is used to liquefy the powder and fuse the powder layers together
layers are formed by sintering or melting the polymeric bed by laser beam which then fuse together
What are the advantages and disadvantages of SLS?
selective laser sintering 3D printing
advantages
- formulations made via SLS have better mechanical properties than those made by PB
- porosity (size/number of pores) can be manipulated by changing the power of the laser beam
- effectiveness of printing can be increased by multiplication of laser beams
disadvantages
- risk of API decomposition after exposure to laser beam
- risk of pharmaceutical excipients degradation
- time consuming
- lack of biocompatible/biodegradable printable polymers
What is the process of fused deposition modelling (FDM)?
based on the extrusion of molten thermoplastic material
the material is heated to just above its softening point then it is extruded through a nozzle and deposited layer by layer, solidifying in under a second
- becomes moldable
What are the advantages and disadvantages of FDM?
fused deposition modelling
advantages
- simple equipment, cheap and fast process
- printed object has good mechanical properties
- have a higher resolution compared to PB
- produce more complex scaffolds
- suitable for the production of implants
disadvantages
- limited thermoplastic materials with good melt viscosity properties
- FDM uses high temperatures which cause degradation of a lot of pharmaceutical excipients and APIs
- loading drugs into the filament is challenging
- requires high quality pharmaceutical grade excipients
- lack of biocompatible/biodegradeable printable polymers
When is FDM printing used?
when you need an object
- that needs to be made quickly
- that must have good mechanical properties
- that has a more complex scaffold
- that is an implant
What is the process of semi solid extrusion 3D printing?
based on the use of a syringe extruder that deposits a viscous and semi liquid material
polymers are mixed with an appropriate solvent to produce a semi solid material with suitable viscosity for printing
the mass is extruded through the syringe orifice by compressed air pressure, syringe plunger or screw
