Centrifuge

Our OpenFuge is based on what was realized in the Biohack Academy.

• A centrifuge is a device that uses the centrifugal force for separating the different materials suspended in a liquid. In the end the heavier elements settle below in the lower part and lighter molecules behind, in the higher part. Two things are of main importace: a motor with enough torque to reach the required g-forces (estimated by the number of revolutions per minute -rpm-) and the radius of the rotor. The torque is propotional to the radius of the rotor and so is the force.

Open fuge
Our OpenFuge is based on what was realized in the Biohack Academy. We changd the sensor that measures the rotational speed and are now using a hall sensor.

Material list

• Arduino UNO1
• 1 DC Brushless motor 2300 RPM/V & Electronic Speed Controller HobbyKing
• 1 Rotary encoder iPrototype, Farnell
• 1 Knob Farnell
• 5 1 Power switch iPrototype, Farnell
• 6 1 DC power jack
• 7 1 12V 5A Power supply Farnell,
• 8 1 Push button iPrototype
• 9 1 10K resistor Farnell,
• 10 4 Rubber feet Conrad
• 11 1 Sheet of 45cm x 95cm 3mm MDF Houthandel Schmidt or Acrilic
• 12 1 5mm shaft adapterHall Sensor Farnell
• Neodymium magnet
• As a rotor we wil use a 3D print of your own design, or this Microfuge 8 Place Rotor
• You will also need some M3 10 mm bolts and nuts

The controll cicuit is very simple. We are only using a rotary encoder, a brushless motor, a hall effect sensor and an LCD that is controlled trough the I2C-protocol.

LCD The LCD is controlled by the Arduino using the I2C communication bus. This bus allows us to controll our LCD with only 4 cables. Two for power supply and two for controll. We are also using an Arduino library that facilitates its use.

Rotary encoder

The Rotary encoder allows us to change the time and the speed that we program for our centrifuge. The rotary encoder also works as a switch that allows us to launch the program that we have selected.

The hall sensors job is it to measure the number of revolutions of our motor which will maintain the number of turns that we have configured for it to work at.

A brushless motor was chosen due to its advatages that are the following: they are designed to last, have a high range of torque and have a descent way of controlling its speed.p>

The speed is controlled with the ESC (Electronic Speed Controll), which controlls the speed based on the entry voltage. The calculation comes from RPM/V=2300kv. At 10 Volt it would be 23000rpm.

This is what the final circuit, connecting all the above mentioned components to our Arduino, would look like:

The rotor of our centrifuge was created in OpenScad. It allows us to change the parameters for creating rotors with different diameters and calculate the resulting g-forces.

We printed our rotor in a 3D printer.

The box for our OpenFuge was cut with a 40W laser out of 3mm acrylic and joined with nuts and bolts.

Here we can see our finished Openfuge. It's only missing a first test in order to see if it works correctly.