Bioengineers at Stanford University in west coast of the United States have created an ultra-low-cost, hand-powered blood centrifuge with rotational speeds of up to 125,000 revolutions per minute . The device, capable of separating blood plasma from red cells in 1.5 minutes, applies the same mechanical principles in a whirligig, which is built by threading a loop of twine through two holes in a button, grabbing the loop ends, then rhythmically pulling.