Difference between revisions of "Team:Grenoble-Alpes/Temperature Control"
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<h5>As biological material is used along the analysis, maintaining a specific temperature within the kit is essential. In order to control the temperature, an electrical circuit was designed using an Arduino card. This system has to first perform an enzymatic cleavage at 37°C .Then, DNA target denaturation at 73°C is realized, and finally, a heat shock occurs which is needed for the bacterial transformation. Whenever the system controlling the temperature must not perform special operations, it keeps the temperature around 37°C. </h5> <h5>The idea we had was to design an electronic card with a resistance thermometer which would measure the temperature. With a direct current source, the resistance variation is transformed into a voltage variation. The circuit also required the design of a voltage divider and as well as an instrumentation amplifier to adjust 0V at 0°C. An Arduino card was also essential to compare the tension relative to the current temperature with the tension relative to the temperature wanted. Eventually, the output tension was sent to a power converter, then to the Peltier device to cold or heat within the kit.</h5> | <h5>As biological material is used along the analysis, maintaining a specific temperature within the kit is essential. In order to control the temperature, an electrical circuit was designed using an Arduino card. This system has to first perform an enzymatic cleavage at 37°C .Then, DNA target denaturation at 73°C is realized, and finally, a heat shock occurs which is needed for the bacterial transformation. Whenever the system controlling the temperature must not perform special operations, it keeps the temperature around 37°C. </h5> <h5>The idea we had was to design an electronic card with a resistance thermometer which would measure the temperature. With a direct current source, the resistance variation is transformed into a voltage variation. The circuit also required the design of a voltage divider and as well as an instrumentation amplifier to adjust 0V at 0°C. An Arduino card was also essential to compare the tension relative to the current temperature with the tension relative to the temperature wanted. Eventually, the output tension was sent to a power converter, then to the Peltier device to cold or heat within the kit.</h5> | ||
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Revision as of 16:55, 26 October 2017
T°C Control
It was at Amont à Aussoi that we had met that night to sleep by the fireside. Credits: Estelle Vincent
How to control the temperature within the kit ?
As biological material is used along the analysis, maintaining a specific temperature within the kit is essential. In order to control the temperature, an electrical circuit was designed using an Arduino card. This system has to first perform an enzymatic cleavage at 37°C .Then, DNA target denaturation at 73°C is realized, and finally, a heat shock occurs which is needed for the bacterial transformation. Whenever the system controlling the temperature must not perform special operations, it keeps the temperature around 37°C.
The idea we had was to design an electronic card with a resistance thermometer which would measure the temperature. With a direct current source, the resistance variation is transformed into a voltage variation. The circuit also required the design of a voltage divider and as well as an instrumentation amplifier to adjust 0V at 0°C. An Arduino card was also essential to compare the tension relative to the current temperature with the tension relative to the temperature wanted. Eventually, the output tension was sent to a power converter, then to the Peltier device to cold or heat within the kit.
Temperature acquisition
The first step was to find a way to detect temperature variations in order to adjust the temperature inside the kit. A specific type of resistance thermometer was used: the Pt100 sensor. In fact, its internal variable resistance changes linearly with the temperature variation. At 0°C, the value of Pt100’s resistance is equal to 100 Ω. But, the problem is that working with resistance variations is not that easy. This is why a continuous current source was added thanks to the LM334 component so as to work with voltage variations.
The current passing through the Pt100 is set with the LM334, so the resistance variation is converted into a voltage variation. To choose that current, it is recommended to fix it under 1mA, so as to avoid burn it. This is why a resistance Rset was added, which value is given by the following equation.
