3D Structures from Melted Thermoplastics
The heater shell for BS31 adapts 10 mL cartridges. The maximum temperature is 120 °C. It maintains cell suspensions at 37 °C or provides melts of thermoplastic materials to build mechanical stiff structures.
Disposable plastic cartridges are not designed for temperatures above 50 °C. The GeSiM stainless steel cartridge (Right) topped with metal needles maintains a homogeneous temperature with low temperature drop to the nozzle footprint.
Thermoplastic melts can have very different properties/consistencies. The stainless steel needle (Second from left, manufactured by GeSiM) has been optimized for melted PCL and MES. Other needles (E.g. steel dispense nozzle, right side) from third party manufacturers work well with low viscous melts. Please contact us with your particular application.
The new High-Power Syringe Extruder prints thermoplastics like PLA (Polylactic acid) at temperatures up to 250°C. It comes with the stainless steel cartridge inside and accepts blends as well as pure PLA. The motor driven plunger extrudes at pressure beyond 100 bar for accurate strand deposition and regardless the consistency of the raw material.
Tablets for Object Fixation
The standard tray for BS3.1 accomodates two well plates (BS3.1 three well plates), e.g. cell culture plates. Trays for glass slides or other targets are available on request. The trays come with a snap-in fixation for quick replacement on the instrument main deck.
Low-Volume Sample Handling
Optionally BS3.1 can be equipped with a pipetting unit. Diverse pipetting needles applies small volumes (0.1 Nanolitre to a few Microlitres) of low-viscous liquids to previously printed scaffold struts. These liquids may contain drugs, cells or particular proteins.
There are two tools available:
- Passive needle for syringe supported displacement dispensing. The lowest dispense volume might be half a Microliter.
- Piezoelectric nozzles for free-flight microdrop dispensing. The lowest dispense volume is in the range of 0.1 Nanolitres:
Piezoelectric GeSiM dispensers emit single drops in the range of 250 Pikolitre (Drop diameter about 50 Microns). Small amounts of proteins or cell suspensions can be applied to single or multiple layers of a bioscaffold structure during the printing process.
- The innovative Twin-Tip-Pipettor operates two separate GeSiM piezoelectric nozzles on a swivel. For aspiration both nozzles dip into separate wells of a 96-well-plate. The droplets of both nozzles than hit together and mix up on the dispense target.
- The volume range between fifty Nanolitres and a few Microlitres is covered best by the solenoid dispense valve (Not for living cells.)
Contradictionary to the cartridge system the pipetting unit aspirates from 96 well plates. Only a few Microliters of each species are required. Heaters are available both for the sample plate and the piezo nozzle for producing microdrops of melted materials.
Piezoelectric Pipettor on BS3.1; Click here for full size BS3.1 video on YouTube
Artificial Tissue from Maccaroni Strands
Soft matrices like Hydrogels are cell friendly materials but hard to print into stable 3D structures. The combination with more stiff thermoplastic scaffolds may cause biocompatibility issues.The pneumatic C/S-extruder (Core/Shell extruder) for BS3.1 allows to combine two materials with different properties in a coaxial manner. The tool is equipped with a kind of double nozzle with different but corresponding inner and outer diameter, respectively. The print parameters can be set individually for both channels in order to match properties of the respective bioinks.
A. R. Akkineni, T. Ahlfeld, A. Lode and M. Gelinsky: A versatile method for combining different biopolymers in a core/shell fashion by 3D plotting to achieve mechanically robust constructs, IOP Publishing Ltd., Oct 2016
Centre for Translational Bone, Joint and Soft Tissue Research
Technische Universität Dresden
Hardening of Scaffold Struts
There are lamp heads with different excitation wave lengths and different wave length available for the exposition of printed scaffold layers (Third party manufacturers). The lense head goes on one of the tool axes of BS3.1. One application is the hardening of UV curable materials.
For high power exposition we recommend the Omnicure 1500. Alternatively, LED-lamps from THORLABS are available with many different wave lengths but at limited power. The max. LED output power depends on the wavelength and is in the range of 50 mW to 210 mW.
Processing of External CAD Data
This extension just comprises software – A dedicated input filter reads in STL files. An STL file describes triangulated surfaces in a three-dimensional Cartesian coordinate system. It is widely used for rapid prototyping, 3D printing and computer aided manufacturing.
The BioScaffolder 3.1 software allows to define inner “scaffold-” structures whereas the STL file brings in just surfaces. Like with the built-in scaffold generator, up to three different materials and different pore sizes can be assigned to the CAD model.
Melt Electrowriting (MEW)
The optional MEW module of BS3.1 combines pneumatic extrusion and high-voltage induced fibre deposition for particular thermoplastic materials. So far PCL 50,000 can be printed.
In contradiction to Melt Electrospinning (MES) Melt Electrospinning Writing deposits each fibre in a regular manner accordingly to the CAD model.
The Melt electrowriting module extends the standard configuration of the instrument by a special tray with embedded electrode, a high-voltage generator and security measures. The minimum strut width is in the range of 10…20 Micrometers. Left side picture shows the print setup with nozzle electrode, the right side shows the high-voltage generator.