Microcentrifuges tested. a. Battery-operated microcentrifuge constructed using a salvaged refrigerator fan motor and a manufactured lightweight centrifuge rotor, mounted in a styrefoam box. b. Battery-operated microcentrifuge purchased from a commercial supplier. c. Electric (110 V) microcentrifuge. d. Manual microcentrifuge constructed from a vegetable spinner with a styrofoam insert to accommodate microcentrifuge tubes (see Methods section for details).