Difference between revisions of "Team:ZJU-China/Hardware"

    We design a complete and high precision microfluidic device. After our calculation and simulation, this microfluidic device reaches a balance of the actual experimental results and dimensional accuracy. This device plays a crucial role In the course of specific experiments. On the one hand, the structure design and the size layout of the device can greatly accelerate the flow of the AHL substance and also allow the cells at the edges of the expanded colony to be washed away by the high flow of the main channel, which allow for continuous exponential growth of bacteria in the chamber. On the other hand, through ingenious circuit design, we have designed a light source system, which can quickly convert two different light sources to meet the needs of light control experiments. In order to reduce the interference of external light , we design a drawer-style shell structure on the basis of micro-fluid plate, which can not only ensure the bacteria to accept light uniformly conducive to micro-fluid plate in the bacteria evenly accept light, but also achieve light-control system and oscillation System coupling.

    Although we have constructed a sophisticated oscillatory system in E.coli, alternating quorum sensing molecules will be retained in the bacterial solution, and the increasing AHL, DPD concentration will affect the stability of the following oscillation. So we also need a microfluidic system to keep away the molecules induced by bacteria and some metabolic wastes. According to the literature of Jeff Hasty et al., We redesigned the devices in the literature to improve the production process, and eventually forming our own microfluidic chip.


    The process begins with closing the media inlet, opening the waste outlet, and slowly injecting the treated bacteria from the cell inlet, during this time, we change the feeding speeds continuously so that the E. coli enters the chamber and colonizes. To reduce the amount of fluid out of liquid waste , we slightly bend the infusion tube. And open the culture medium entrance, to access the medium to constantly update the cell’s liquid environment.

    After a discussion about our literature, we settled the size of each trap and the length, width, and height are 100 um, 85um and 5um, respectively, which is the most favorable one for oscillation experiment and dynamic response model. Two traps stand 150um apart at the same side, while for the opposite side, the groove is 200um wide and 100um deep which is convenient for fluid to pass. Also, according to our calculation, we are quite sure that this design can increase the flow of AHL quorum sensing substance, and can let the cells at the edge of expansion colonies be washed away, making it possible for bacteria in the traps maintaining a continuous exponential growth.For observing convenience, we divide the traps into 4 groups, and each has 30 traps. The distance between two groups is sixty thousands um.

    For overall experiment, we also designed a device to help us using the microfludic chip. As for the body part, the upper platform has four through-holes, for putting in the LEDs. The lower part has the two slots, size of each slot are the same as the microfluidic chip. And we have a shading baffle whose size is appropriate with slots. Devices and shading baffle are produced by 3D printing, the material we chose is resin. It has smooth surface, high precision, and good hardness. Taking into account that the device will be placed in the thermostat, we used a kind of resin that has small thermal deformation coefficient, this will ensure that assembling won’t be a problem. In order to ensure that the experiment will not be interfered by the stray light, all surfaces are sprayed with black matte paint.