Extract DNA at Home with a 3D Printed Centrifuge

Biotechnology is powerful, but only for those with the tools to experiment with and utilize it. The DIYbio movement seeks to put the tools and techniques used in well-funded laboratories around the world into the hands of ordinary people who have an interest but not the means to investigate biology.

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One of these tools is the centrifuge. Centrifuges come in many shapes and sizes to fit a wide variety of laboratory needs. There are large machines with precise controls for RPMs, G-force, timers of all kinds, and even ones with temperature control. Then there are mini-centrifuges used for simple DNA extraction and quick-spins for mixing the contents of test tubes.

This 3D-printed DIYbio mini-centrifuge was designed to do the latter and has actually been used in a real university biology lab doing real protocols. Building one is easy, and hopefully after you’re done reading this, you will have ideas of how to improve on this one, or maybe the inspiration to tackle other types of otherwise inaccessible and expensive pieces of equipment with 3D printing.

Print the Parts

Figure A. Assembly of the printed parts

Go to F.Lab’s Thingiverse page for the centrifuge to download the STL files. Because of the size of the parts, you may need to run multiple print jobs — this gives you a chance to switch colors like we did (Figure A). Print infill of 30% is recommended. Be sure to duplicate the feet so that you have 4 in total.

Program the Arduino

Figure B. Click for larger version

It’s a good idea to program your Arduino first and test everything out before assembling the entire centrifuge. Upload the code below to your Arduino. Wire everything together as in the diagram (Figure B), but make sure to use only temporary connections between the 3 drone motor wires and the ESC, because you’ll need to disconnect them and reattach them during the assembly process.

#include Servo myservo; int potpin = A0; // analog pin used to connect the potentiometer int val; // variable to read the value from the analog pin int listo = 13; void setup() { pinMode(listo, OUTPUT); digitalWrite(listo, LOW); myservo.attach(9); //pin de control al ESC arm(); // Función para armar el esc } void loop() { digitalWrite(listo, HIGH); //Sierra preparada LED intermitente delay(200); digitalWrite(listo, LOW); delay(200); // reads the value of the potent. (value between 0 and 1023) val = analogRead(potpin); // scale it to use it with motor. Limitado a 100. val = map(val, 0, 1023, 55, 140); myservo.write(val); } void arm() { //Función de armado myservo.write(0); delay(1000); myservo.write(30);...

Scientists turn toy into valuable tool for medical diagnosis

paper centrifuge
paper centrifuge

Medical lab equipment often showcases high-tech at its best. Devices can perform complicated tasks, such as separating blood into its parts, quickly and easily. But these machines often are difficult — even impossible — to use in poor countries or at remote field clinics. Often expensive and bulky, they tend to require training to use. And most are powered by electricity. But researchers have just unveiled a simple, low-cost human-powered device useful for medical diagnoses. It can separate blood into its different parts.

Best of all, it’s so simple a child could run it. Indeed, it is based on a toy that’s been around for thousands of years.

Manu Prakash is a bioengineer at Stanford University in California. There, he designs medical devices that can be used easily by anyone anywhere in the world. A few years back, his team invented a microscope made largely of paper that costs less than a dollar to make.

On a trip to the East African nation of Uganda, a few years ago, Prakash was surprised to see an expensive centrifuge being used as a doorstop. Medical labs use these devices to separate liquid mixtures, such as blood or muddy water, into their different components. Based on what they learn from those components, doctors will tailor a patient’s treatment.

But the clinic did not have electricity. So no one could use this machine.

centrifuge machine
This centrifuge can separate blood or other liquids into their various parts to aid in disease diagnosis. But these machines are costly and need electrical power. And that can prevent their use in many poorer parts of the world.

The key part of a centrifuge is its rapidly rotating interior. Think of it as a small version of a top-loading washing machine. In a centrifuge, though, the interior chamber spins faster than the parts in a car’s engine. Anything inside a spinning centrifuge experiences a force that slings it away from the center of rotation and toward the device’s rim. This is similar to how wet clothes in the washer get squished against the inside wall of the drum during the spin cycle.

When a centrifuge spins a test tube of blood to separate out its various parts, the vial is loaded in with its base pointing outward. Rotation forces outward the densest parts of the blood — platelets and blood cells. Lighter parts, such as the fluid or plasma, stay on top. Doctors or lab technicians can then separate each layer for tests that guide treatment. Without a centrifuge, such tests become difficult, if not impossible.

The centrifuge that had become an expensive doorstop inspired Prakash’s team to invent something that could serve the same purpose. Their device would have to spin very quickly. It would have to be cheap to make and easy to use. And it would have to run without electricity.

Previously, Prakash notes, people had suggested employing kitchen devices as a low-cost centrifuge, such as an egg beater or handheld mixer. But these tools could…