Ti-6Al-7Nb
Selected over Ti-6Al-4V to address the report’s concern about possible vanadium release, while retaining the strength and stiffness needed for the piston rod.
CAD / SOLIDWORKS · FINAL-YEAR TEAM PROJECT
A bioprinter head for microgravity.
I designed a piston-driven extrusion head concept for biomanufacturing in space. This page follows the key decisions: why extrusion, how the mechanism works, how the assembly was modelled, and why its materials were selected.
01 / WHY
Why choose extrusion?
The report screened inkjet, laser-assisted and extrusion printing against the project’s space-use criteria. Extrusion offered the best overall balance for this concept: a broad bio-ink range, scalability and cited spaceflight heritage, with moderate resolution as the trade-off.
| Criterion | Inkjet | Laser | Extrusion · selected |
|---|---|---|---|
| Bio-ink viscosity | Low | Medium | Low to high |
| Resolution | High | Very high | Moderate |
| Cell viability | Moderate (heating noted in report) | High | Moderate to high |
| Cost & complexity | Low | Very high | Low to moderate |
| Print speed | Fast | Slow | Moderate |
| Scalability | Poor | Poor to moderate | Good potential for larger structures |
| Space readiness | Low (droplet placement relies on gravity) | Moderate (equipment described as fragile) | High (report cites Redwire’s BioFabrication Facility) |
Design decision: extrusion was selected as the practical trade-off. It supports a broad viscosity range and larger constructs; its resolution is moderate, so it was not the strongest option on every criterion.
02 / WHAT
The concept
The chosen technique is extrusion. Within it, the project uses a piston-driven mechanism: a lead screw advances the piston, displacing bio-ink from the reservoir through the nozzle and onto a substrate.
The piston gives direct positive displacement control over flow and volume, with less sensitivity to pressure fluctuations than pneumatic delivery. The report preferred it over screw-driven extrusion, which adds mechanical complexity and mass.
InputRotational input turns the lead screw.
MotionThe screw converts rotation into linear piston travel.
OutputThe piston pushes bio-ink through the nozzle toward the substrate.
Two different uses of “screw”Here, the lead screw moves the piston. In screw-driven extrusion, the screw itself conveys the bio-ink. The report selected piston-driven extrusion, actuated by a lead screw.
03 / HOW
The SolidWorks assembly
My SolidWorks work focused on the extrusion components and their assembly interfaces. The actuator model was imported as reference geometry; the assembly shows how the piston, reservoir and nozzle work together as a head.
04 / WHY THESE MATERIALS
Material selection
Ansys Granta EduPack was used to screen materials against each component’s role, prioritising biocompatibility and the relevant mechanical and operational requirements.
Medical-grade polycarbonate
Chosen to balance toughness with transparency, so the reservoir can withstand handling while allowing ink-level visibility.
Medical-grade polypropylene
Selected for a single-use nozzle: its chemical resistance, cost and manufacturability support simple replacement and sterility assurance.
Scope / next steps: the assembly is a concept and omits supporting structures such as a frame, bearings and guides. The report leaves nozzle-orifice sizing dependent on the bio-ink and print target; assumed loads and material compatibility also need validation. Prototype and flight testing were outside scope.