Step 8: Lessons learned and future work
- Learning how stepper motors work and how to drive them was a really valuable learning experience, but we could have saved ourselves a lot of time and effort by adapting some of the RAMPS (RepRap Arduino MEGA Pololu Shield) technology that has already been well developed for precisely this purpose by the 3D printing community. In particular, the Pololu stepper drivers already have microstepping capability built-in.
- Building your own XY stage for essentially free is great! But we are using these stepper motors for something they were never designed for, and it's starting to show. We are already getting some trouble with the bottom stage skipping occasionally, presumably because we've been resetting the sage by hand too often, which puts a lot of wear on the plastic bits that track the worm gear. It would be easy enough to buy some stepper motors brand-new, lasercut a frame to hold them, add some micro switches for end stops, and code a position reset function in software.
- Once you start sourcing brand new stepper motors, laser cutting a frame, and wiring up RAMPS electronics, why not just start with a 3D printer instead? If we get tired with our current BioPrinter version, that's probably the direction we'll go. Cost would likely go up by an order of magnitude or so though...
- Having a single print head has its own limitations. If we really wanted to do some sort of tissue engineering, we'd love to be able to print multiple cell types, and put some scaffolding material in between. We could potentially put two inkjet cartridges back-to-back. The solution the Big Boys in this field use is syringe pumps. Imagine having several syringe pumps sitting next to the printer, each feeding a different printing material via a thin tube to a needle mounted on the print head. Stay tuned...
Now the elephant in the room... What the heck do you do with your own BioPrinter? I don't think a place like BioCurious will ever compete head-to-head with companies like Organovo in terms of printing human tissues or organs. For one, animal cells take a lot of effort to maintain. Plant cells are much easier to work with though! Don't want to give everything away, but stay tuned for some of our next Instructables!
Meanwhile, here are some ideas:
- Print gradients of nutrients and/or antibiotics on a layer of cells to study combinatorial interactions - or even to select different isolates from an environmental sample.
- Print patterns of growth factors on a layer of eukaryotic cells to study cell differentiation.
- Print two or more microbial species at different distances from each other, to study metabolic interactions.
- Set up a computational problem as a 2D pattern of engineered microbes on an agar plate.
- Study Reaction-Diffusion systems
- Print 3D structures by over-printing layers using the inkjet head. Now you can consider doing all the above in 3D!
- Print cell in a sodium alginate solution, onto a surface soaked in calcium chloride, to build up 3D gel structures (similar to spherification process in Molecular Gastronomy)
- More ideas? Post them in the comments!