Process¶
From the implication and application week I had a clear idea about the fabrication method but less so for the material. During the holiday I decided to focus on the different materials and recipes that could be suitable for my application.
overview of material that I decided to focus on divided into complexity to manufacture and the potention they have to fullfill the goal of the project
rough shedule for the project divided into material and hardware development needed for the project, green bars indicates developments and blue research
Biomaterial¶
From the material research a decided to divide them into 3 groups based on their characteristics and how realistic they are to realize within the tight time frame:
1) BIOPLASTIC¶
Will mainly be used as a backup if printing cells will not turn out to be a viable solution as well as a method to easily try out different printing structures without the need for a sterile environment and long growth time that otherwise would slow down the printing process.
Sodium alginate can be used as a base but needs to be mixed with additives and plasticizer (glycerin) to enhance mechanical properties such as tensile strength and hand feel.
Additives to increase mechanical properties:
Chitosan: is derived from chitin, a fibrous compound found mainly on the hard outer skeletons of crustaceans and in the cell walls of some fungi. Chitosan is biodegradable and has been used in the development of antimicrobial films for food packaging.
* 2% Sodium Alginate
* water
* 2-3 drops of food colarant
* 3% Sodium Alginate
* water
* 2-3 drops of food colarant
* magnetic stirrer
* glas jars
* Sodium alginate combined with the food colorand (Figure 1F).
* dissolved and vortexed at 60o C
* Once cooled, the hydrogel was placed in a syringe with a 1inch 27G needle for printing
Initial experiments during bio fabrication week showed that mixing chitosan with sodium alginate increased the tensile strength but decreased the flexibility of the Sodium Alginate.
Nano cellulose:is very structured with stacked chains that result in stability and strength. The strength and stability comes from the straighter shape of cellulose caused by glucose monomers joined together by glycogen bonds. The straight shape allows the molecules to pack closely. Cellulose is very common in application due to its abundant supply. Cellulose is used vastly in the form of nano-fibrils called nano-cellulose.
Nano-cellulose presented at low concentrations produces a transparent gel material. This material can be used for biodegradable, homogeneous, dense films that are very useful in the biomedical field.
Keratin: Is a protein that is found in hair, feathers, hooves, and horns, and it is not commonly used to make fabric. However, researchers have been experimenting with using keratin to make biodegradable fibers for textiles. These fibers are made by breaking down keratin from sources such as chicken feathers and spinning it into yarn. The resulting fabric is soft, durable, and has similar properties to wool. It is still in development and not yet commercially available.
Reflection:¶
Sodium Alginate should be a good base polymer since it have good heat resistance and is partially water resistant.
There are several methods (according to chatGBT) that can be used to improve the water-resistance of sodium alginate-based bioplastics. Some of these include:
• Adding other polymers: Mixing sodium alginate with other polymers, such as polyvinyl alcohol (PVA) or polyethylene glycol (PEG), can improve the water resistance of the resulting bioplastic.
• Crosslinking: Crosslinking the alginate chains can improve the water resistance of the bioplastic by making it more rigid and less likely to swell. This can be done using chemical crosslinking agents, such as epichlorohydrin, or physical crosslinking agents, such as calcium ions.
• Coating: A coating of another material, such as a wax or a plastic, can be applied to the surface of the bioplastic to create a barrier that prevents water from penetrating the material.
• Using different alginate sources: Different species of brown seaweed contain varying amounts of alginates with different properties, thus finding the right species that has a higher water resistance properties could be a solution
However, it is worth noting that this roadmap will depend on the external supplier and are somewhat diverting from the original plan to eliminate (as far as possible) external supply chains.
2) PROTEIN BASED BIO-INKS¶
Collagen and silk fibroin is commonly used in tissue engineering and there are several already existing bio-inks formulated for the FRESH protocol. Similar to the bioplastic roadmap this would allow for a speedy sampling process and stronger and more attractive physical properties than Sodium Alginate.
Both collagen and silk fibroin have strong mechanical properties, but they have different strengths and weaknesses.
Collagen is a natural protein that is found in skin, bones, tendons, and other connective tissues. It is known for its high tensile strength, which makes it a good candidate for use in medical implants and other applications that require strong and flexible materials. Collagen is also biocompatible and biodegradable, which makes it a good choice for use in medical applications.
Silk fibroin, on the other hand, is a protein that is found in silk. It is known for its high tensile strength and high modulus, which makes it a good choice for use in textiles, biomedical applications, and other applications that require strong and stiff materials. Silk fibroin is also biocompatible and biodegradable, but it's more resistant to degradation than collagen
Overall, Silk fibroin has higher tensile strength and modulus compared to collagen. However, collagen has better flexibility and better biodegradability.
Reflections:¶
Both this materials looks like they could be possible to use and should be possible to “brew” in-house however for the project I think I could utilize that the inks are commercially available which would simplify the process considerably.
3) LIVING CELLS¶
AlgaeIn the bioprinting field algae seems to be mainly used for their photosynthetic or nutritious properties and sometimes used in combination with bacterial cellulose to increase its tensile strength however red algae have been found to have high tensile strength, comparable to that of synthetic fibers such as Kevlar.
Mycelium There are not a lot of projects available around bioprinting mycelium but generally speaking mycelium have a low tensile strength however many companies have been able to produce attractive leather using different mycelium species so in theory, it should be possible.
Bacterial cellulose Bacterial cellulose is a highly pure form of cellulose that is produced by certain types of bacteria. It is known for its high tensile strength and high modulus, which makes it a good candidate for use in medical implants, textiles, and other applications that require strong and stiff materials.
Reflection of material research:¶
Based on the variety of research studies available for bioprinting bacterial cellulose and the accessibility of kombucha culture media I decided to focus my research on this field.
Once decided on the material to use I was faced with the question of how to develop the printing protocol.
I discovered that there are two completely different ways that I could work with the material. Which way would be the best for my specific application would form the main question to answer for this project:
1) work with it as a living-ink meaning printing it out while it is still a living bacterial culture. This is a technique that have been proposed within the field of tissue engineering however not yet for fashion applications
2) As a “dead” purified bio-ink a tested technique in the fashion field. Few companies like Scobytex grow BC membranes that after purification can be used as a leather alternative however me knowingly never been used as a bioprinting ink.
