Spiropen

The Spiropen can be a sustainable alternative to conventional felt-tip and graffiti markers. It is made from recyclable and biodegradable materials such as algae and PLA. The ink is also derived from algae. In the quantities used, it is harmless to the environment because the ethanol it contains evaporates. Compared to conventional markers, the felt tip can be easily replaced if damaged or worn out, thereby extending the pen’s lifespan. An interesting side effect of the chlorophyll-based ink is its lack of permanent lightfastness: under UV light, the chlorophyll first turns brown and eventually disappears completely. This allows paper to be reused multiple times or walls and facades to be temporarily decorated without leaving permanent marks.

To develop the pen, we first focused on its design and shape, aiming to make it as effective and minimalist as possible. We then researched chlorophyll extraction and conducted experiments in the BioLab using various techniques and different mixing ratios of ethanol and Spirogyra to isolate the green pigment. We found that the extracted pigment was poorly soluble in water. Therefore, we decided not to completely boil off the ethanol. For the casing, we fabricated a steel press mold to create a uniform surface using heat and pressure. Initial tests, however, showed that the pressed structure was not sufficiently stable. By coating the exterior with chitosan—a natural adhesive—we were able to significantly improve its strength. The final algae component was the felt: The algae were layered in the direction of the fibers and secured with hemp twine. Finally, we 3D-printed the cartridge, lid, and end caps from translucent PLA to fit the casing precisely.