In biology, an incubator is a device used to grow and maintain microbiological cultures or cell cultures. Incubator design is based on design from Biohack Academy.

Main differences:

• Instead of Arduino microcontroller, it will be controlled by Raspberry Pi 2.
• It should have a smaller volume. In order to achieve that it will be used different heat source (heating foil) and no fan.

Materials

Description	Supplier NL	Cost
3mm MDF 95 x 45 cm	Wood store, like Houthandel Schmidt
Expanded polystyrene (EPS), 2cm thick	Praxis	€ 7.99
Temperature sensor DS18S20	Conrad	€ 5.32
4.7kΩ resistor for temperature sensor
LED and resistor for it
MOSFET	Conrad	€ 1.01
Heating foil	Conrad	€ 5.49

Design

In order find the most suitable design several hypotheses ere tested and these are some results.

1. just a plain carton box
2. 2cm think insulation (EPS) without gluing it (led to some warm air leakage)
3. no fan - checking distribution of the warm air by 2 temperature sensors (bottom & top)
4. heating foil connected to 5V - using the same power source as for Raspberry Pi

Without cover:

Wiring, note that temperature sensors are DS18S20 and heating element is the heating foil not a Peltier element.

Software to run the incubator can be found here.

Conclusion after this experimental design:

1. Heat distribution is not uniform as it could be expected.

1. Heating foil with 5V power supply is not good enough. Alone it can reach around 35°C but within container temperature stays below 30°C. Next try out should be with 12V - maximum voltage per specification.

2. 4cm thick EPS instead of 2cm.

Incubator casing

For incubator box (casing) the following Magic Box template is used. It is a modified version of Press-fit Box. The main difference is that one side can be configured differently: number of steps (t_steps) and fitting (tpf). That allows 5 sides to strongly fit together and the remaining (top) side just to be used as a cover. SVG files can be generated using the template and online Magic Box tool. SVG laser cut file example.