Team:Worldshaper-XSHS/Applied Design
Worldshaper-XSHS applied design
Applications of Nic-E.coli in life (like in a smoking room) Principle
Concentration of Nic-E.coli growth was related to the concentration of nicotine (see Figure 1 and Figure 2 below), so we decided to use the second version E.coli with the fluorescent expression to design a test equipment, which could be used to detect whether the nicotine content in the air reached a dangerous level.
Design method
We used 3D printing technology to construct our product design into a physical model. The main body of the product model was a cuboid of 15cm in length, 7cm in width and 7cm in height.
The chamber was filled with bacteria liquid. A fan was used to extract the upper part of the gas to form a low-pressure area. The atmospheric pressure would pump the gas to be tested from the other side into the inlet pipe, which was bent down and connected to the bottom of the device, so that the gas could fully contact with the liquid and water-soluble nicotine could be transferred from the air into the bacteria liquid. After that, we got the bacterial fluid, whose protein expressed fluorescence with the effect of nicotine by measuring the fluorescence and comparing with existing datas to calculate the nicotine concentration. This was our primary hypothesis. However, through simulation experiments, we found the defects and deficiencies of the existing device :
1.The bottom area of 15cm x 7cm means that there was nearly half liter of bacteria liquid in the device when operating, which was not reasonable from the perspective of convenience or safety. 2.The first version device which used fan to extract caused the air outlet pipe diameter become larger. Also, bacterial fluid-air inside the device-outside air formed the interconnected system so that the fan’s working efficiency would greatly reduce if we used gauze or mesh. 3.The fan was unable to extract equal volume every time, so it was not conducive to get the nicotine concentration after detecting fluorescence. Based on this,We improved the second version device.
In the design of the second version product, we reduced the device size-the actual internal bottom area was about 16cm squared-reduced the amount of bacterial liquid that needed for work. The equipment also adopted the piston pumping way likes inflator, which enabled filters device to reduce the possible Ecoli leakage properly. Because the piston way was used to pump air, the gas was a fixed column of air volume when the piston pumps back and forth, bringing great convenience for us to exactly extract the volume we want.
We added a certain amount of second-version Nic-E.coli in the container and introduced the nicotine-containing gas into the test chamber through piston pulling air. (According to the optimum concentration obtained by the experiment, we can calculate appropriate volume of the gas that be added) After a steady period of time, for example, putting the second version E-coli at the concentration of 0.0001 g/L, the fluorescence is most obvious at 3 hours), ultraviolet light stimulated the fluorescent protein. Fluorescence intensity detected by light sensor was measured and the amount of nicotine in the previously gas was calculated the nicotine content. Having a higher nicotine level in the air, the measured value of the light perception would be higher. Thus, warning device would remind people to open the window, reducing the total nicotine in the room.
Our two version devices apply the same experiment principles, It had been proven in the laboratory.
The internal bacteria solution of the device was working in a sealed state, so it would not react with the outside environment.
According to the experiment record, at the concentration of 0.0001 g/L nicotine, the second-version detection system had a stable fluorescence expression within 1~3h. When we used a 2-by-5cm piston pump, we should slowly pumped the gas every five seconds to ensure that the nicotine is fully dissolved into the bacterial fluid. From starting detecting to the one hour when we can observed the fluorescence expression, we were able to obtain 100 to 200 times more the amount of nicotine in the air, at which time the nicotine concentration was in the proper range for the second-version monitoring system. We sat different swept volume to adapt to different occasions. For instance, in the smoking room, the device warns when nicotine harms to human health; in other public places like office, the equipment only reminds people to ventilate – Installing the nicotine concentration second version device in the 60 square meters of closed classroom, we are able to see the alarm when someone smokes.
Indisputably, the detection is feasible and effective.
Note 1: (The piston pumping and pumping air device is shown below.) We utilized different pressure between the gas inside and atmosphere outside to lead air containing nicotine to nutrient solution. Push-pull could let more nicotine mix with water, so confirming that nicotine content can be used for detecting the fluorescence expression of Nic-E.coli.
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