3D printing

Question 1

Additive manufacturing (general 3D printing process)

Answer 1

3D model required- form MRI or made from software, the 3D printer sliced the model into many layers and 3D printing layer by layer

Question 2

Subtractive manufacturing

Answer 2

Conventional, a block of material is required in the beginning, the materials are removed from block to create the final shape

Question 3

Advantages of additive manufacturing over subtractive manufacturing

Answer 3

Can make very complex structures in small time frame

Question 4

Selective laser sintering

Answer 4

lay an even layer of powders using a roller
a laser beam is scanned across at pre-decided positions to fuse powders together
the stage is lowered and a second layer of powder is laid
the process is repeated to form a 3d structure
can use: metals, polymers and ceramics

Question 5

What is 3D printing? (specific technology)

Answer 5

lay an even layer of powder using a roller.
a binder is jetted onto selective positions to fuse powders together.
the stage is lowered and a second layer of powder is laid.
the process is repeated to form a 3d structure.
Major difference is:
binder used to bind powder together not laser

Question 6

Inkjet printing

Answer 6

Working mechanism:

Piezoelectric actuator generates a picoliter drop.
drop ejects and reaches a substrate at pre-decided positions according to the 3D structure to be printed.
Solidification of the ejected drop.
Repeat the cycle to form a 3D structure.
materials: photopolymerizable monomers

Question 7

What is stereolithography

Answer 7

A UV laser is scanned across a layer of photopolymerisable monomers at pre-decided positions according to the 3D structure to be printed.
monomers polymerise and solidify under UV; stage is moved to allow another layer of monomers to fill the space.
the process is repeated to form a 3D structure.

Question 8

Fused deposition modelling

Answer 8

feed polymer into a heater.
melt polymer.
extrude polymer through a nozzle while stage is moved in XYZ according to the 3D structure to be printed
extruded polymer strand cools and solidifies to form the 3D structure.
Printable materials: Thermoplastic polymers

Thermoplastic materials are materials that soften and become mouldable upon heating and harden upon cooling.

Examples: Polyetherether ketone (PEEK), polycaprolactone, polylactic acid.

Question 9

Processing conditions for cell printing

Answer 9

Processing conditions that are harsh to live cells are involved in some 3D printing technologies, therefore they are not suitable for printing cells.

High temperature – fused deposition modelling and selective laser sintering
long UV exposure time – stereolithography
3D printing – toxic binders

Question 10

Cell inkjet printing

Answer 10

Piezoelectric actuator generates a picoliter drop.
drop ejects and reaches substrate at pre-decided positions according to the 3D structure to be printed.
solidification of the ejected drop. Repeat the cycle to form a 3D structure.
using cell suspension

Question 11

Laser assisted printing

Answer 11

a laser beam shines upon an energy absorbing layer at pre-decided positions,
As a result a shockwave is generated resulting in an ejection of a drop which reaches a substrate.

Question 12

Microextrusion

Answer 12

Working mechanism

a hydrogel or hydrogel/cell mixture with a suitable viscosity range is loaded in a cartridge.
the material is extruded through a nozzle by pressure or mechanical forces while stage is moved in XYZ according to the 3D structure to be printed.
extruded hydrogel strand forms a 3D structure.
Printable materials: hydrogels or hydrogel/cell mixtures with a suitable viscosity range

Question 13

Hydrogels in extrusion bioprinting

Answer 13

Hydrogels are non-fluidic colloidal networks or polymer networks that are physically or chemically crosslinked and contain a large amount of water.
Viscosity of a hydrogel is an important material property for successful extrusion bioprinting.

Question 14

Patient-specific vs. Mass-produced medical devices

Answer 14

3D printed medical devices currently fall in the category of “custom-made medical devices”. An example of custom-made medical devices is orthopaedic insoles.

Each one is unique which makes it impossible to sample the devices during a quality inspection. This means that their manufacturing process must implement the appropriate quality requirements. The latter must be translated into a legal requirement imposed on the manufacturers of these 3D-printed, patient-specific medical devices.