A turbidostat is a feedback controlled continuous culture device that keeps cell density constant. Commercially available turbidostats are not designed with academic research goals (such as long term evolution or synthetic circuit characterization) in mind and as a result tend to be too large and have inflexible proprietary software. We've designed an inexpensive, open source, 3D printable, eight vessel turbidostat that can be constructed with commodity parts and open source circuits. Our design is programmed with an open source extensible Python interface that can used to expand the functionality beyond a standard turbidostat. Presently we are using this device to grow microbes in a constant environment for days to weeks while sending chemical signals to characterize gene circuits in bacteria or yeast. Our collaborators at UW, Rice and UC Berkeley have assembled copies own using our designs with their own modifications. Complete designs and assembly instructions can be found at the turbidostat wiki.
We have made many robot testbeds in which robots self assemble or self organize. In one such testbed, triangular 'programmable parts' were stirred randomly on an air table and self-assembled into preprogrammed shapes. In another, our 'robotic chemistry' parts behaved like molecules in a chemical reaction that was controllable by light input. Designs and specifications for these robots, that you can read about on our publications page, are available upon request.