A team at the University of Melbourne, Australia, are developing 3D printable gels that could be used to make self-healing smartphone and computer screens.
Demonstrated by 3D printed self-rolling “cigars” and a healing sea star, the gels are made from an interesting mix of ingredients, the likes of which you could find in your medicine cabinet and the kitchen.
The base material for research conducted by Milena Nadgorny, Zeyun Xiao and Luke A. Connal is a water-based gel known as PHEMA. In 1961 Czech chemist Otto Wichterle used PHEMA to invent the first soft contact lenses. The gel is transparent and, when crosslinked, is capable of absorbing large amounts of water, which is key to an ability to self-heal.
The crosslinked PHEMA gel in this study is produced as 12 different variations, some that are spreadable, others that are stiff, and a selection in-between that can be 3D printed. Of these gels, one particular variation is singled out as the best consistency for 3D printing, and used to create a range of shapes.
To start, a butterfly is drawn to demonstrate design flexibility.
From here research moves on to shapes that can be activated using a secret ingredient.
Cigars and sea stars
Nadgorny, Xiao and Connal use a 3D Bioplotter from EnvisionTEC to 3D print the gel through a syringe. To investigate self-healing abilities they 3D print a sea star shape, then make a deep cut across the top with a scalpel.
After 30 minutes of self-healing the gel closes the cut. A further 30 minutes of ambient drying and the sea star fully heals becoming solid.
A “cigar” shape is then demonstrated as having self-rolling abilities, the likes of which could be used in objects that self-assemble (see 4D printing at MIT).
A 3D printed “cigar” shown unravelling. Clip via supplementary materials “2D and 3D-printing of self-healing gels: design and extrusion of self-rolling objects”
A dash of cinnamon
The 3D printed gels at Melbourne are activated by benzaldehyde, an organic compound used as a flavouring in almond extract for cakes. Synthetic benzaldehyde is typically obtain by extraction from cinnamon oil.
Another culinary ingredient contributing to self-healing 3D printed gel research is chitosan, which can be extracted from the shells of crabs, shrimp and other crustaceans.
Conclusions of the Nadgorny, Xiao and Connal study state that,
3D-printing of self-healing gels is a facile approach for a selective deposition of protective coatings, and a fabrication of smart and dynamic objects.
Featured image: No more nightmares. A 3D printed gel from the University of Melbourne could be used to make self-healing computer screens and smartphones. Image of cracked computer screen via: Mischief Makers Manual