Students at Rice University have modified an ordinary $30 salad spinner into a rudimentary centrifuge that medical clinics in developing countries could use to manually separate blood without electricity.
The Sally Centrifuge, as it's called, trades speed for quantity, spinning up to 30 tubes at 950 rpm compared to a typical centrifuge that spins 4 capillary tubes at speeds up to 10,000 rpm. That's fast enough to diagnose anemia and help save lives according to the Rice team.
The plan is to take three instances of the novel device abroad this summer to Ecuador, Swaziland, and Malawi as part of Beyond Traditional Borders (BTB), the university's global health initiative that brings new ideas and technologies to underdeveloped countries.
"We were essentially told we need to find a way to diagnose anemia without power, without it being very costly and with a portable device," said Lauren Theis, one of two students involved in the project.
The centrifuge indeed meets the criteria demanded by their global health class project: It's inexpensive, portable, and operates without electricity. Apart from the spinner, the parts list includes plastic lids, cut-up combs, yogurt containers, and a hot-glue gun.
How does it work? According to a Rice news item, when tiny capillary tubes that contain about 15 microliters of blood are spun in the device for 10 minutes, the solid part of the blood (red blood cells) is thrown outward into the bottom of the tube and the lighter liquid part comes to the top (plasma). The hematocrit, or ratio of red blood cells to the total volume, measured with a gauge held up to the tube, can tell clinicians if a patient is anemic. That detail is critical for diagnosing malnutrition, tuberculosis, HIV/AIDS, and malaria.
Maria Oden, a professor and director of Rice’s Oshman Engineering Design Kitchen (OEDK) said: "Many of the patients seen in developing world clinics are anemic, and it's a severe health problem. Being able to diagnose it with no power, with a device that's extremely lightweight, is very valuable."
The salad spinner joins a growing list of low-cost novel solutions that have the capacity to change lives and help solve critical challenges in developing nations. One Laptop per Child (OLPC) and water filtration designs like the Aquaduct bicycle are great examples, and countless more examples can be found on sites like Design for the other 90%.