Chapter 8. DIY BioPrinter

Patrik D'haeseleer

Bioprinting is printing with biological materials. Think of it as 3D printing, but with squishier ingredients. There’s a lot of work being done at research labs and big companies like Organovo on 3D printing of human tissues for drug testing, or even of whole human organs for transplantation. But the basic underlying technologies are surprisingly accessible: it’s all based on inkjet printing or 3D printing—technologies that are readily available to the DIY scientist.

$150 DIY BioPrinter
Figure 8-1. The $150 DIY BioPrinter built at BioCurious

When we first opened the doors on the BioCurious lab in Sunnyvale, we wanted to pick a couple of community projects around which we could build a critical mass—ideally projects that weren’t purely limited to the wetlab, so we could have newcomers walk in the door and start participating right away. Bioprinting seemed to fit the bill. Over the course of about a year, meeting once a week with a constantly changing set of participants, we actually managed to put together a rudimentary printer that could print E. coli cells onto an agar plate using an XY platform built from parts scavenged from old CD drives and an inkjet printhead. And it actually worked the first time around! We are able to print a few lines of "I <3 BioCurious" in E. coli expressing Green Fluorescent Protein.

I <3 BioCurious
Figure 8-2. I <3 BIOCURIOUS, printed in E. coli expressing Green Fluorescent Protein on an agar plate

None of this would have been possible even five years ago. The idea to use CD drive stepper motors was borrowed from another DIYbio group, Hackteria, in Europe; the InkShield driving the print head is an Open Hardware project originally funded on Kickstarter; the InkShield and stepper motors are controlled by an Arduino; and some of the acrylic was laser cut at TechShop. None of that whole amazing infrastructure was around just a few years back.

So now that we actually had a working artefact, we needed a way to share it with the wider DIYbio community. But how do you publish your achievements in DIYbio? Some might have gone with a github repository. We decided to write a detailed description on the Instructables website, which seemed a better fit for a project how-to with lots of pictures. You can find that Instructable at http://www.instructables.com/id/DIY-BioPrinter. Ironically, our $150 DIY BioPrinter Instructable won two contests on the Instructables website, winning us a $1500 Macbook Pro and a $1500 UP! 3D printer—a 20× rate of return!

So what do you do with a DIY BioPrinter? Make yourself a DIY organ transplant? Not likely. Animal cells are a pain to maintain in a community lab. And human cells pose a biosafety risk, since you’re growing cells without an immune system that can catch whatever nasty bugs you’re carrying and spread them to other people. So rather than compete with the multimillion dollar biomedical applications that industry is pursuing, at BioCurious, we’ve decided to strike out into a direction where we have almost zero competition: instead of trying to print human organs, why not try…plant organs? Specifically, we’d love to print a synthetic leaf and get it to photosynthesize. The reaction we get to that idea is usually "Wow, cool!" And that is exactly why we’re doing it. As DIY biohackers on a shoestring budget, we don’t need to ask ourselves who’s going to fund our research, or what commercial applications it might have—after all, there aren’t too many plants desperately in need of a leaf transplant. But anything we accomplish in bioprinting with plant cells will be novel and publishable. And heck, we’ll probably stumble across something with commercial possibilities, but that’s not our primary motivation.

Our original BioPrinter instructable made quite a splash, with articles in Wired, MIT Technology Review, Makezine, and a bunch of major tech blogs. We know of several groups that are building their own BioPrinter based on our example, including at least two academic labs that are planning to use it as an actual research platform. (Can you autoclave an inkjet cartridge? Only one way to find out…) The week after we published our instructable, Nicolas Lewis, the designer of the InkShield driving our inkjet print head, ran out of stock and had to start production on a new batch of InkShields.

Would we build the same BioPrinter with scavenged parts if we had to do things over again? Probably not. It was a wonderful learning opportunity for us, especially considering none of us in the BioPrinter group had any experience with bioprinting, and hardly any of us knew anything about inkjet technology, Arduinos, laser cutting, stepper motors, or how to drive stepper motors. We all taught each other what little pieces we knew, and we managed to pull off something incredibly cool. I would still recommend our current design as a learning tool that can be built on an incredibly small budget. But it definitely has its limitations: it’s only an XY platform, and adding a Z stage may be problematic given the low-power CD drive stepper motors. And using an inkjet cartridge as a print head means you can only print with liquid cultures that have the consistence of inkjet ink.

Our further hardware developments since the instructable have focused on three areas:

  1. Replacing the cobbled-together stepper motor drivers on our old BioPrinter with a RAMPS shield, which is the electronic of choice for the 3D printing community these days
  2. Adding a bioprinting head onto the brand-new 3D printer we won (people starting from scratch may want to look at some of the very cheap 3D printer models coming out now, like the $200 MakiBox, to use as a dedicated bioprinting platform!)
  3. Replacing the inkjet print head with a set of syringe pumps

Below is a DIY syringe pump we threw together: just a $10 linear stepper motor, pushing directly on the plunger of a small-diameter disposable syringe. It works great, at a cost that is a couple orders of magnitude less than professional syringe pumps.

$10 DIY syringe pump
Figure 8-3. Under construction: a $10 DIY syringe pump, capable of delivering 0.5ul/step

The syringe pumps should allow us to print using gels that maintain their shape, enabling 3D prints. Or perhaps better: print using sodium alginate and cells in one syringe and calcium chloride in a second. Where the two come in contact, the alginate will solidify, trapping the cells in a biocompatible matrix. Now imagine what crazy things you could do with cells that are engineered to express alginase under specific conditions so they can resculpt the 3D matrix that holds them in place. Add in some cell-to-cell communication, chemotaxis, and bacterial cellulose biosynthesis pathways, and you have yourself a complete toolbox for 3D pattern formation. The possibilities are endless.

This project has been an often chaotic and organically evolving collaboration between dozens of people. Too many to list here, but I’d love to thank every one of you who’ve contributed—you know who you are!