The thermocycler is an essential piece of equipment in molecular biology. It is used to control temperature of solutions in numerous molecular biology techniques. Its main application is in DNA amplification by means of Polymerase chain reaction (PCR). The thermocycler works by heating or cooling an aluminum block with several housings for reaction tubes (0.2 mL volume). In the current setting, the temperature is controlled with +-1°C accuracy. Biochemical reactions are performed by enzymes which are active at a specific temperature range. For example, in DNA extraction, a protease is needed to digest tissues and release DNA. Such protease is active at 65°C and becomes inactivated at 95°C. In this context, a thermocycler can be used to incubate the DNA extraction mixture at the optimal temperature (65°C) and then stop the reaction by increasing the temperature (95°C). In the case of a PCR, the thermocycler proceeds through 3 temperature steps in a cycle, to allow specific events in the reaction to occur at each step.
The thermocycler is homebrew and was built by the maker community during the LowCostPCR workshop. The participants also covered partially the costs of the components (now 100% of it), feel free to donate some money to help buying some reagents and keep it running.
How Does It Work
The case is laser cut and it’s transparent for educational purposes, so all components can be clearly seen in the inside. On the top there is an aluminum block with conical housings for reaction tubes of 0.2 mL, and on the side there is a sensor monitoring the temperature, which an accuracy of +/-1°C. Right below the block, there is a peltier element which is responsible for heating and cooling the block. The heat is dissipated through a heat-sink for microprocessors. On the side of the case it is possible to see a breadboard and an Arduino. The breadboard hosts few electronic component, among which there is a microprocessor to calculate and match the heating/cooling process with the readings of the temperature sensor. The arduino is used to communicate with the user and trasmit the data between the user and the microprocessor, and thus control temperature cycles and schemes. On the bottom there is a computer power supply with the on/off switch. When switched on the fan starts working, but the arduino gets its power from the laptop through the USB port. The thermocycler is controlled thanks to an Arduino. At the moment, it needs to be connected to a laptop, but we’re developing a phone app that would communicate with it via bluetooth.
Light spectrometers are used to split light into its different wavelengths. In biology and chemistry it can be used to analyze the contents of solutions. Different solutes absorb light in a different manner. This can be visualized and measured with a spectrometer. Essentially our spectrometer is a refraction film and a web-cam. Alessandro Volpato showed us how to build it during a workshop.
The freezer is a common freezer re-purposed for storing biohacking materials and reagents. We equipped it with a transmitter to keep track of the freezer’s temperature. Biotop members will be notified in case the freezer gets too warm. You can see the current temperature below.