Tales of a 3D Printer : Printed Scan Data: Eggshell

Wednesday, February 19, 2014

Printed Scan Data: Eggshell

Today, we finally printed more data from our trip to the Advanced Light Source earlier this year using only open source software. We ended up with an approximately 5 cm model of an eggshell printed from scan data from an original sample that was a few millimeters long.

reconstructed data on computer

Why an eggshell? Well, here is the abstract from the student group whose experiment involved the eggshell:

We at the Black Pine Circle Scientific Studies Division, want to scan an eggshell. Pores on the surface of the shell allow air and moisture to go through. A larger, 3D-model will provide tactile information. Designs may be made to create new housing materials, for hot, humid places. We will be beaming hard X-rays through the sample from various angles, giving us a computer model, which can be 3D-printed. This information can be studied for housing materials, to create a new type of ultra-modern house that literally breathes in places with moisture buildup.

Besides, eggshells are pretty fascinating! Scientists have known for a long time that the chicken eggshell is 95-97% calcium carbonate crystals, but it wasn't until the electron microscope came around that they discovered, "Rather than simple layers of crystals of calcium carbonate, the shell was shown to consist of a very complex type of mineral formation, with a protein matrix as its foundation." (journal article, and perhaps way more detail than you will ever need about eggshells!)

The Exploratorium states succinctly, "Bumpy and grainy in texture, an eggshell is covered with as many as 17,000 tiny pores. Eggshell is made almost entirely of calcium carbonate (CaCO3) crystals. It is a semipermeable membrane, which means that air and moisture can pass through its pores. The shell also has a thin outermost coating called the bloom or cuticle that helps keep out bacteria and dust."

Another site explains, "The outer cover of the egg, the shell comprises 10-11% of total egg weight. On an average the eggshell weighs 5-6g, with remarkable mechanical properties of breaking strength (>30N) and is 300-350 micrometer thick. This structure plays a crucial role in protecting the contents of the egg from the microbial and physical environment and in controlling the exchange of water and gases.

More research uncovered these two diagrams, which makes me think that we actually printed the eggshell "upside down" or more-accurately "inside up," revealing those mammillary layer structures that touch the inner, organic membrane! Interesting to consider.