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<h2>The components</h2>

<h2>The components</h2>

We use quite the same photodiode (TSL230RD) – same as the TSL230RP-LF but in surface mounted device (SMD) – and an Arduino Uno. Arduino is a single-board microcontroller created to make electronics more accessible. The main asset of the photodiode is that the output can be either a pulse train or a square wave (50% duty cycle) with frequency directly proportional to light intensity. Since we are using a microcontroller, it is easy to calculate a frequency with the digital input of the microchip thanks to high or low level and we will have a better resolution because low frequencies are easier to measure than low voltages. For the optic part we use a domestic LED lamp and a cube filter from a microscope with excitation and emission filters and an adjustable lens. A domestic LED lamp was chosen to allow us not to buy several high-power LEDS and built a card with a heat sink. This lamp illuminate with 520 lumens in a cone of 40° under 12V and 6W. The low voltage was chosen as a safety condition and the small angle to avoid losing to much light. The excitation filter is a green interferential filter to excite the red fluorescent protein and the emission filter is only a colored filter to have all the red light in order to have a more efficient measure. In the cube there is also a dichroic mirror that reflects all the green light and transmits all the red light. This mirror enables us to separate completely the photodiode from the light source.

We use quite the same photodiode (TSL230RD) – same as the TSL230RP-LF but in surface mounted device (SMD) – and an Arduino Uno. Arduino is a single-board microcontroller created to make electronics more accessible. The main asset of the photodiode is that the output can be either a pulse train or a square wave (50% duty cycle) with frequency directly proportional to light intensity. Since we are using a microcontroller, it is easy to calculate a frequency with the digital input of the microchip thanks to high or low level and we will have a better resolution because low frequencies are easier to measure than low voltages. For the optic part we use a domestic LED lamp and a cube filter from a microscope with excitation and emission filters and an adjustable lens. A domestic LED lamp was chosen to allow us not to buy several high-power LEDS and built a card with a heat sink. This lamp illuminate with 520 lumens in a cone of 40° under 12V and 6W. The low voltage was chosen as a safety condition and the small angle to avoid losing to much light. The excitation filter is a green interferential filter to excite the red fluorescent protein and the emission filter is only a colored filter to have all the red light in order to have a more efficient measure. In the cube there is also a dichroic mirror that reflects all the green light and transmits all the red light. This mirror enables us to separate completely the photodiode from the light source.

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