Testing 30-70 wt% MGS-1 conditions with 425 and 150 µm particle size using methodology from Bioink Composition Testing. Observing whether the gel can be easily extruded from a syringe and maintain its layers after crosslinking.
Materials & Methods
Materials
100 mM calcium chloride
Plastic containers for
sieved sand
mixing the gel
Spatula
10 mL syringe
Petri dish
Deionized water
3wt% alginate solution (use prepared one from 2025.06.17)
2 sieve sizes * 5 wt% (30, 40, 50, 60, 70) conditions = 10 total tests (no replicates)
Shapes extruded are shown below
Calcium chloride solution was added after shapes were extruded
Figure 1. Solid shape (top) and hollow shape (bottom) extruded
Results
Images
150 µm particle size MGS-1
425 µm particle size MGS-1
Image 12. 30-70wt%, 425 µm MGS-1 taken 14-15 hours after calcium chloride submersion.
Observations
Both sand sizes were easy to extrude through a 5 mL or 10 mL syringe
The sand solution itself was thick enough for both sieve sizes to allow stacking of layers (alginate solution adds “sticky” texture to bio ink)
The bioink seem to be disintegrating over time at 150 µm sieve size
This is also visible with increasing MGS-1 wt %
With the 425 µm MGS-1 sieve size, higher wt % seem to hold the layers better
This could be due to: 1. larger sand size, 2. change to fresh calcium chloride solution
Gels were still soft after 14-15 hours of crosslinking for both 150 µm and 425 µm MGS-1 sieve size
Attempts to move the bio ink with a spatula resulted in the structure falling a part
Bio ink lightened in colour gradually after calcium chloride submersion
The 40 wt% 425 µm regolith appeared to be slightly more solidified than the 70 wt% regolith
Both structures were still very soft and unable to be lifted from the plate
suggest lower wt % which can provide better calcium chloride diffusion and ultimately better diffusion
Summary
There was no noticeable difference between the sieve sizes in terms of resistance, extrusion ease, or printability of bio ink
Any “potential solidification” observed likely linked to the sand “stickiness” rather than calcium chloride crosslinking with alginate solution
The calcium chloride solution alone is not sufficiently diffusing through the regolith to allow crosslinking with the alginate solution and eventual solidification
Literature will need to be investigated to determine current strategies for MGS-1 used in building materials
Current bio ink production protocol will need to be optimized for MGS-1 conditions
A repeat of this experiment must be conducted to ensure proper protocol design
The layers of bioink held together much better for the 150 µm compared to the 425 µm regolith
Image 12. 30-70wt%, 425 µm MGS-1 taken 14-15 hours after calcium chloride submersion.