A colleague asked if I might be interested in developing some designs for a home/school-targeted bioreactor product. I was!

Initial sketches.

Side view of the layout for an insulated, temperature-controlled, semi-automated bioreactor concept.

Top view.

 First prototype on display at Maker Faire Bay Area, 2014

First prototype on display at Maker Faire Bay Area, 2014

 The initial prototype, based on above sketches, was created in a matter of weeks, but there were refinements to make...

The initial prototype, based on above sketches, was created in a matter of weeks, but there were refinements to make...

The next prototype, started in March 2015, was based on the concept of a water cooler which served to continuously ferment a bacterial culture. 

The vessel was a 6 gallon glass carboy. After the base was made, I drilled some ports in the top (bottom) of the carboy to allow liquids to circulate & agitate the culture in a pump-over technique.

After several hours of drilling and grinding, I finished boring the holes for a fill/feed/airlock in the center, and the circulation port closer to the side. 

Now, work on designing the plumbing layout began.

A diaphragm pump was chosen to circulate the liquids because they are self-priming and less-detrimental to bacterial populations than centrifugal pumps. 3-way valves controlled flow & filling (manually) and a solenoid valve controlled the dispensing of the liquid culture.

Shortly after, the prototype was tested for leaks, washed, then a starter culture of facultative anaerobes (EM-1) was added along with filtered water and blackstrap molasses. The pump's outlet hose was angled in such a way that the pump-over action caused a vortex to form in the liquid, showing proper mixing of the contents.

With the addition of an electric heat strap, the culture was off and running!

With a proof-of-concept model out of the way, we began designing a more-robust and fully-featured prototype. 

Here is the result of some MIG welding (before grinding) at TechShop Mid-Peninsula.

It was decided that this model needed stronger agitation than circulation alone could provide, so I began testing out various mixer blades. 

There were a LOT of small components specially designed for this prototype, many of them cut out of acrylic plastic sheets. 

The end result of a few intense weeks of fabrication was a machine which could continuously 'brew' a liquid culture of aerobic or anaerobic bacteria and/or fungi (automated kombucha machine, anyone?) with solid/liquid inputs & liquid output dispensing being mechanically regulated, agitation (spin mixing), color-based indicator lights, and aqueous chemistry monitoring (pH, EC, DO, temperature, etc.). 

First test of the agitator/mixer creating a vortex in water.