Team:UCAS-China/Hardware
HARDWARE
Introduction: Our whole system was triggered by light[1], so E. coli needed to be illuminated when cultured. To make quantitative analysis, we needed to strictly control light intensity and wave length. Our hardware series kept upgrading as our demands increased.
Material: Considering the small volume and high efficiency, we chose 3W LED as our light source after careful calculations[2]. We managed to buy 11 kinds of LEDs with different wave lengths (390-400nm, 420-430nm, 430-440nm, 450-455nm, 460-470nm, 495-500nm, 515-530nm, 590-595nm, 600-605nm, 620-630nm, 655-660nm).
Design: To satisfy multiple needs, we designed two kinds of hardware. One for solid medium, the other for fluid medium.
1. Hardware 1.0 for solid medium
Process: Using thermal conductive adhesive, we fixed the LED beads with substrate to our radiator, which looked like a sunflower. In the following picture, you can see our light source component as a whole, “sunflower”!
Figure 1. Our light source component- “Sunflower”
We managed to dig a hole in a container, which our sunflower perfectly fitted in. We used wires to connect the sunflower with a power source, and the plates inside the container could be illuminated by our lovely light! You would see some of them in the following pictures.
Figure 2. Inside the container.
We made four containers illuminated by LEDs. Then we put four containers into a huge incubator. We called these containers our “Hardware1.0”
Figure 3. Four containers in the incubator.
Generally, this system worked pretty well, and we incubated several colored mediums with sufficient illumination all night.
2. Hardware 1.5 for fluid medium
The space was limited for our sunflowers in the 96-well plate shaker. We used aluminum foil instead of sunflowers. And it worked well.
The 12V constant voltage power resource could provide energy for four LEDs at the same time.
Then we fixed them inside the lid of the shaker. Four plates are separated from each other by aluminum foil to avoid light leakage.
Figure 4. Internal structure of our hardware for liquid.
Figure 5. External look of our hardware for liquid.
We tested our hardware and found some problems.
1. Light intensity was not adjustable.
2. The distribution of light intensity at the bottom was uneven, especially in the 96-well plate shaker where light intensity was high.
We used different colors in areas which had different fluorescence values or optical densities. The deeper the color was, the value that it stood for was higher. The following pictures visually display the fluorescence or optical density distribution in a certain area in a 96-well plate.
Figure 6. The distribution of optical density value of E.coli in the 96 hole plates irradiating by blue light(460-470nm).
Figure 7. Correspondence between color and value.
Figure 8. The distribution of fluorescence intensity of E.coli in the 96 hole plates irradiating by green light(515-530nm).
Figure 9. The distribution of fluorescence intensity of E.coli in the 96 hole plates without illumination.
The light intensity could reach 35000 lux at the center of the 96-well plates, while it was 15000 lux in marginal area.
Solutions:
1. As for light intensity, on one hand, we used PWM to change current waveform so that the valid value can be manipulated; on the other hand, we altered distance to change light intensity subtly.
[1] PWM
Figure 10. Pulse Width Modulation (PWM)
Figure 11. Concise schematic diagram of PWM
[2] Distance
