TITLE: Towards standardisation of parameter reporting for melt electrowriting
AUTHORS: Sönke Menke, Biranche Tandon, Juergen Brugger

[DESCRIPTION]
This protocol aims to help researchers collect all necessary data to make their research in melt electrowriting more reproducible and easier to compare to the data of others.

[GUIDELINES]
As there is no standardised way of reporting parameters for melt electrowriting yet, this protocol aims to help with the standardisation (see King & Bowlin, 2021). Hence we recommend following all the steps and reporting them in the corresponding publications along with the results.

The data points resulting from the steps under the section named "Printing information" should be collected before every print and stored as digital record safely. For publication, the printing information of the constructs used should be made public.

[STEPS]
SECTION: Device information (Per device/configuration used)
1. If your system has been published before, make sure to add a reference to it, otherwise share a build guide or what modifications to published systems have been made as done by Eichholz et al. 2022 or Reizabal et al. 2023.
SECTION: Device information (Per device/configuration used)
2. Note the type of extrusion used. Examples are syringe pumps, pressure-driven systems or extruder based systems.
SECTION: Device information (Per device/configuration used)
3. Note the configuration of the high voltage (HV) system. Where is the HV applied, which field direction is being used.
SECTION: Device information (Per device/configuration used)
4. Note which parts of the printer are moving in which direction(s). While a static collector with a moving head, and a moving collector with static head should produce the same results, there might be differences observable.
SECTION: Printing material information (Per material)
6. The supplier should be named for every commercially available material .
If the material is selfmade, the synthetic route should be added or referenced. For blends, a detailed description of the production process should be made available. 
SECTION: Printing material information (Per material)
7. Note name and chemical composition.
SECTION: Printing material information (Per material)
8. Note molar mass (and dispersity) if known.
SECTION: Printing material information (Per material)
9. Note any pre-treatments prior to printing (storage under Ar, at XYZ °C,...).
SECTION: Printing material information (Per material)
11. Note melting, glass transition, and recrystallisation temperature (if known), ideally obtained via DSC.
SECTION: G-Code information (Per code)
14. Each code should be made available in full.
SECTION: G-Code information (Per code)
15. If the code was created using a G-Code generator, it should be made public as well or cited if that has been published before (like Devlin et al. 2024). 
SECTION: G-Code information (Per code)
16. The code should be written without complicated language that might not be replicated on all machines like "for" loops or similar code. Device specific code can of course be used but should be commented so users with different machines can understand it and adapt it to their systems.
SECTION: G-Code information (Per code)
17. In the beginning of the code important parameters, especially the print parameters (see printing information section), should be defined.
SECTION: Printing information (For every print)
19. Note ambient temperature and humidity (°C, %RH).
SECTION: Printing information (For every print)
20. Note time and date (YYYY-MM-DD, hh:mm).
SECTION: Printing information (For every print)
21. Note nozzle diameter (Gauge or mm).
SECTION: Printing information (For every print)
22. Note collector-nozzle distance (mm).
SECTION: Printing information (For every print)
23. Note HV (field orientation and strength, kV).
SECTION: Printing information (For every print)
26. Note flow rate/applied pressure/extrusion rate. This should ideally be given in µL/h or nL/h. Pressure should be given in bar (if PSI is  being used, conversion should be made in text but original value also stated).
SECTION: G-Code information (Per code)
18. Furthermore, layout (flat/tubular, angle, number of layers) and number of scaffolds should be stated.
SECTION: Printing information (For every print)
24. Note material.
SECTION: Printing information (For every print)
25. Note reservoir temperature and collector temperature (if applicable, °C).
SECTION: Printing information (For every print)
27. Note relative collector speed (ideally in mm/min).
SECTION: Fibre information (for every print discussed)
29. Fibre diameter should be measured via SEM in a standardised way across all printed constructs. To avoid human influence, ImageJ plugins such as GIFT can be used. Fibre diameters should be reported with standard deviation, number of measurements (n) and number of scaffolds (N).
 

SECTION: Fibre information (for every print discussed)
30. Note inter-fibre spacing and determine the lowest possible per material (if new material).
SECTION: Fibre information (for every print discussed)
31. Note maximum layer height achieved per material.
SECTION: Fibre information (for every print discussed)
32. Show representative SEM images (with scale bar) showing also the defects if present (bridging/gapping, bad stacking, pulsing,...). 
SECTION: Fibre information (for every print discussed)
33. Compare fibre diameter to expected result (if applicable).
Show analytical/theoretical validation.

SECTION: Device information (Per device/configuration used)
5. Note the collector specifications. Is it flat, tubular, or different? What is the material of the substrate that is being printed on?
SECTION: Printing information (For every print)
28. Note duration of print (estimated).
SECTION: Printing material information (Per material)
12. Note stability at melting or printing temperature, ideally obtained via TGA.
SECTION: Printing material information (Per material)
10. Note the grade of the polymer (commercial grade, medical grade,...). This is especially needed for materials intended for biomedical applications.
SECTION: Printing material information (Per material)
13. Take an image of the jet formed at the nozzle.