Answer :
The author includes the sentence about using the centrifuge as a doorstop to provide a bit of humor and to highlight the low-tech, resource-efficient nature of the new malaria test. The centrifuge, a piece of laboratory equipment, is a common fixture in scientific settings, but using one as a doorstop showcases the adaptability and versatility of such tools in novel contexts. This anecdote adds a touch of whimsy and helps make the subject matter more engaging for the reader.