C2-HC11

Question 1

techniques for 3d printing:

Answer 1

Fused deposition modelling (FDM)
3D plotting
Stereolithography (SLA)
Digital Light Processing (DLP)
Continuous Liquid Interface Printing (CLIP)
Binder printing
Selective Laster Sintering/ Melting (SLS/ SLM)

Question 2

Fused deposition modelling (FDM):

3D plotting:

Answer 2

Fused deposition modelling (FDM)
○ You have a polymer (thermoplastic material; can be melted and become solid again) that you heat till the temperature is above the melting point. Then it is pushed out the tip and it can be used to print. So the polymer is extruded as a liquid and it cools down again to a solid at room temperature.

3D plotting
○ Direct writing and printing of paste-like materials.
○ Used for ceramics/ cements, pastry (e.g. chocolate), hydrogels.

Question 3

Stereolithography (SLA):
Digital Light Processing (DLP):
Continuous Liquid Interface Printing (CLIP):

Answer 3

Stereolithography (SLA)
○ Is uses light & liquid material (photopolymer). You have a basin with a liquid photopolymer that is sensitive to light. When the light hits, the photopolymer solidifies. Above the basin, a laser is located which is able to move and prints the model layer by layer by locally shining a light (laser) on the photopolymer.

Alternative to laser scanning: Digital Light Processing (DLP) >a projector is used to project an image on a wider area, this is faster. But it is less precise.

Disadvantage: when printing rapidly the print is moved too fast from the bottom of the reservoir and the print get stuck. Therefore, printing using SLA or DLP is very slow. A solution is Continuous Liquid Interface Printing (CLIP) > consist of an oxygen permitting layer at the bottom of the reservoir. This is important since oxygen allows the material to settle. So the layer will help in stopping the bottom layer from solidifying and the speed can be stepped up.

Question 4

Binder printing:

Selective Laster Sintering/ Melting (SLS/ SLM):

Answer 4

Binder printing
○ Reservoir filled with particles (powder) and substances that trigger the particles to bind together. The printing head sprays on these particles with a sort of glue (e.g., a acid that partially melts the powder together). After one layer is printed, the reservoir is lowered, a new powder is put on top and the second layer can be printed.

Selective Laster Sintering/ Melting (SLS/ SLM): instead of shooting glue on the powder, a laser is being shot on the particles. These particles (e.g., metal) melts and merges multiple particles together. Then new materials are put on and a new layer is printed.

Question 5

Which technologies can print living cells?

Answer 5

Most of the techniques are able to print living cells, except for FDM and SLS/SLS EBM which are the techniques that are also not able to print hydrogels. The techniques require an extreme high temperature or extremely high laser intensity. The cells will not survive this.

Question 6

Biofabrication and bioprinting=

Answer 6

Biofabrication and bioprinting= the automated generation of biologically functional products with structural organization from living cells, bioactive molecules, biomaterials, cell aggregates such as micro-tissues, or hybrid cell-material constructs, through Bioprinting or bioassembly and subsequent tissue maturation processes.