Innovative and cutting-edge technology using hydrogel is now given a newly developed application. Instead of silicon and chips, they created bio-responsive 3-D prints that look like constructs or a tattoo. What is pure genius is that it is alive, and bacterial cells react when touching the skin. Shaped like a tree with cells that react to chemicals and molecular substances in the skin. It automatically lights up and where the proper bacteria have encountered a specific stimulus or chemical.

 The researchers who are in MIT's Department of Mechanical Engineering, headed by Xuanhe Zhao and Timothy Lu professor of biological engineering and of electrical engineering and computer science. Creating the living tattoo as a collaborative project to create a combo of biologically active materials and use the method for wearable sensor and bio-responsive displays. Tailored with customized living cells, combined with hydrogel as the chassis holding it. Programmed to display an indication of shifting heat and acidity levels as an example.

For more precision to see how to guess what happens to the cells in 3-D print, a model was created to pre-empt any errors and success in many conditions too. All these steps in the model will be the basis of bio-responsiveness structures using hydrogel.

The best material for housing bacteria

Getting the material to house the cells is the most crucial step that will keep the shape intact. Using inks that are temperature sensitive and polymer-based, as shape-changing chassis for the cells. Another one is photosensitive 3-D printed structures, made of polymers that changed shape when exposed to light. Attempt to used complex cells from mammals ended in failure because they broke easily.

Everything was solved with bacteria cells that were more durable and survives better than mammal cells. The hydrogel used to house the bacteria, and it worked out better, with a water-based chassis to keep bacteria alive. Engineers used hydrogel together with pluronic acid as a compatible pair for 3-D prints. The use of hydrogel is perfect for use, with good flow for custom 3-D printing machines.

The living computer is the next after tattoos

The component for assembling a living computer based on 3-D prints made from hydrogel and required bacteria are now complete. Printing the hydrogel chassis, then adding nutrients into the solution to keep bacteria alive inside the channels.

Success with the ink allows high-resolution prints at 30 micrometers for structures in the gel chassis. Cells per line that is 3-D printed are few for now, but improvements are expected from the project. The hydrogel formed when exposed to ultraviolet light. The last stage is attaching the elastomer to the cell as the last part, onto the skin.

Testing how well the bio-responsive 3-D print performs was done wiping compounds on the backhand. Later the patch was lighting up in response to the stimulus of compounds. Experiments went further, by devising ways for bacteria to talk to each other, by creating an input and output layer of bacteria. Positive results were gained when the filament layer reacted to the right bacteria in the patch.

Conclusion

 Engineering bio-responsive 3-d structures with hydrogel, and with custom bacteria design for any purpose is the organic equivalent of silicon wafers. The tech has apps for computing and any use it is designed for. Best of all, it can be compact and offers a revolution of sorts in creating an alternative technology base on organic.

Read: Engineers 3D Print Programmed Cells Into Living Devices