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Collaborations

Why we collaborate with iGEM teams

What teams we collaborated with

What did we do for each of the collaborations

-- link to Harvard Collab section

-- link to BostonU Wetlab section

Harvard Collaboration

This chip was designed to encapsulate sodium alginate, calcium chloride, and cells suspended in media in droplets for later use in the Harvard iGEM team’s keratin skin patches. These chips consist of three aqueous inputs that combine without mixing into one input that is then pinched by the oil channels at the droplet generator to create droplets.

Version 1

Since this chip passed the proof of concept experiments using colored water, this was the chip used, in combination with the TERRA Adapter during our collaborative meeting with Harvard on August 9, 2018. The chip was tested with biology a total of 4 times, each time eventually leaking before creating a stable stream of droplets. An analysis of the failure concluded that pressure around the chip was ineffective at keeping the requisite area around the channels sealed given that there was too much empty space between the channels and the pressure applying binder clips. The future chip should either be smaller in overall area or the channel design should be spread out over a larger portion of the chip area. Harvard iGEM left us with the material needed to attempt to encapsulate their droplets on our own for when the new chip is assembled and tested.

Version 2

Following the observations made when testing the initial version of this collaboration chip, the overall chip area was significantly reduced while the actually design was made more spaced out. This, combined with a thicker layer of PDMS, lead to the chip seal holding. The chip was capable of creating the proof of concept droplets out of different colors of water, but when the different solutions were introduced, the viscosity of the sodium alginate solution inhibited the formation of droplets. Now that the chip no longer leaks, it was decided that perhaps shortening the length travelled by the segregated solution would reduce the effects the viscous solution.

Version 3

This version of the Harvard Collaboration Chip was not designed by the 2018 BostonU Hardware iGEM team, but by one of our mentors Ali Lashkaripour. It is similar to last version with a few differences. First, the three liquids meet right before the droplet generator. Second, the overall dimensions of the chip are smaller which leads to a better seal. Lastly, the channels have varying widths due to the initial purpose of chip. Lastly, the channels have varying widths due to the initial purpose of chip. This last detail is not relevant to the chip’s purpose here. When this chip was tested with the sodium alginate solution, it behaved similarly to to the last version, with the viscous solution creating tailing droplets but no individual encased droplets. After observing this repeatedly under a variety of different flow rates ratios, it was decided that a new geometry was needed to achieve the collaboration’s desire outcome. Using a similar chip with only a single input, we were able to conclude that the while the sodium alginate solution was capable of forming droplets, it did so independently of the chip geometry. After this test and some literature review, a T-junction was decided upon for the new version of this collaboration chip.

Version 4

This latest version of the chip utilizes a T-junction instead of the droplet generators we have been using in the rest of our chips. Similar to the previous chip, all three inputs meet right before the T-junction. Unlike the other chips, a T-junction uses only a single stream of oil instead of pinching the solution with two streams, letting the droplets formed partially independent of geometry. During the first test with parameters similar to those tested in the last design, the problem remained.