3D Printing

3D Printing

1. Selective Laser Sintering

   • Most common. Focused laser beam fuses together powder
   • Metal, polymer, ceramic
   • Lay an even layer of powders using a roller. Laser beam scanned across at pre-decided positions to fuse powders together. Stage is lowered and second layer of powder is laid.

2. 3D Printing

   • Metal, polymer, ceramic
   • Lay even layer of powder using roller. Binder is jetted onto selective positions to fused powders together. Stage lowered and second layer laid.

3. Inkjet Printing

   • Photopolymerisable monomers
   • Pizoelectric actuator generates a picoliter drop. Drop ejects and reaches a substrate at pre-decided positions according to structure. Solidification of ejected drop.

4. Stereolithography

   • Photopolymerisable monomers
     • UV laser is scanned across layer of photopolymerisable monomers at pre-decided positions. Monomers polymerise and solidify under UV. Stage is moved to allow another layer of monomers to fill space

5. Fused Deposition Modelling

   • Polyetherether ketone (PEEK), polycaprolactone, polylactic acid
   • Feed polymer into heater & melt. Extrude polymer through nozzle while stage is moved according to structure. Extruded polymer strand cools & solidifies

6. Cell Printing

   • Processing conditions = harsh so not suitable. High temp: fused deposition modelling & selective laser sintering. Long UV exposure time: stereolithography. 3D printing: toxic binders
   • Inkjet printing with cell suspension
   • Laser Assisted Printing
     • Using cell suspension. Laser beam shines upon an energy absorbing layer at pre-decided positions. Then shockwave is generated resulting
   • Extrusion Bioprinting
     • Hydrogels or hydrogel/cell mixtures with a suitable viscosity range
     • Material loaded in a cartridge. Material is extruded through a nozzle by pressure or mechanical forces while stage is moved
     • Hydrogels are non fluid colloidal networks or polymer networks that are physically/chemically cross linked and contain large amounts of water. Viscosity important for successful printing (maintain own weight and shape)
       • Hydrogels = shear thinning. Smear slowly = move viscous
         • Shear rate = how quickly it can be deformed (quickly deformed due to increased rotation = increased shear rate)
         • Shear thinning = increasing shear rate = gradual viscosity (curve)

7. 'custom made medical devices'

   • Each unique so impossible to sample in quality inspection. Manufacturing process must implement appropriate requirements (legal requirements)