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12/13 Wildcard ## Week 13: In this week, we learned how to ... wildcard! # Recitation - mechanis, actuation, automation - half cnc and half hand tool With plastic the holes can be smaller than the screw e.g. 4.4mm hole and m5 screw # Class notes Way to use websocket with esp32 using mods and native html. - Tapered Heat-Set Inserts for Plastic - harmonic drive slows down the movement while remaining the torc. I chose Sustainable Materials. We kicked off the week with a presentation by Vlasta on the state of the art of bio-materials and her work on biodegradable material for houshold and industry compost. Some keytake aways: - novel field - a lot of recipes to be tested, [materion](https://materiom.org) library For this week's, we aimed at creating and characterizing various materials to try and replicate the materials often used for experiments. The biomaterials we used are: - Sodium Alginate: Extracted from brown algae, sodium alginate is prized for its gel-forming ability, biocompatibility, and biodegradability. In soft electronics, it's used to create flexible, stretchable matrices for wearable sensors and skin-like electronics, benefiting from its hydrophilic nature for ion-conductive applications. - Glycerin This hygroscopic polyol compound serves as an effective plasticizer in biomaterials, enhancing flexibility and durability. Glycerin's incorporation into polymer matrices prevents brittleness, particularly under environmental changes, making it suitable for durable, skin-compatible electronic patches and flexible displays. - Cellulose As the most abundant organic polymer, cellulose offers robustness and flexibility. Its application in soft electronics includes serving as a base for flexible substrates and composites, where its integration with conductive materials creates lightweight, highly conductive films for screens, sensors, and wearable tech. ## 1. Preparation  ## 2. Weighing out the ingredients  ## 3. Mix the ingredients Preferably in a mixer that can be warmed up so the gelatine can more easily dissovle  ## 4. Spread out the mixture. This step turned out to be the most crucial step to our goal. The flexibility and stretchyness of the biofilm strongly correlates with the thickness. The thinner the better was Vlasta's advice. ## 5. Crosslinking biopolymers We tried to crosslink some samples to augment the consistency and properties. ## 6. Dry and label the results  We successfully created a thin, translucent film.  With the reslts of our previous recipes, we altered the recipe slightly and added glycerine to make the biofilm more stretchy and bendable.   This one turned out to be very very close to the leathery material we were tried to achieve. It was flexible and slightly stretchy. On the left is the goal material and the to the right is our attempt at recreating it.  ## Lasercut One parameter to see if this material can be used as an alternative for FabLab style prototyping is to see if it is lasercuttable. To our surprise: Every material we made were cuttable. They withstood the temperature and nothing melted. The thin translucent film when engraved gave a nice white, matte texture, similar to when you engrave acrylic.  Since there have been many papers exploring inducing graphene on biomaterial e.g. potatoes. We tried it too with a high cellulose content sheet of biopolymer. It got quite dark but not conductive yet.  ## "Vinyl" Cutting We also tried to cut some kirigami structures with the biofilms. It was easy cuttable, but most sheets were too brittle to hold the intricate cuts without tearing.  But our final recipe's sheet was able to hold the cuts! It behaved like a plastic film that can be folded and creased without tearing. We noticed the thickness throughout the sheet varied due to the not so precise pouring method. This effected the uniformity significantly. We made a Kirigami buttons and the material had nice springiness.   ## Soft Robotics Finally, we attempted some soft actuation with our material. Jack provided some fibers. We first embedded the LCE fibre. The Fiber de-adhered from the thinner parts of the sheet but stuck to the thicker part of the poured biofilm. It created a tendon like structure. Further more we tried to weave the Fiber through the sheet. Here is a collection of the materials and their respective recipes. Material Recipe Show and Tell --- ## Next Steps - --- # Resources - files - Material Recipe --- ↳About