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.

The initial prototype, based on these 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.