Helen M. Free and Alfred Free | Science History Institute

“He came up with the idea of a dipstick, or urine test strip—a strip of paper coated with a chemical that turns color in the presence of a particular chemical substance in urine. The Frees developed Clinistix for Miles, the now ubiquitous “dip-and-read” test for glucose in urine. Helen and Alfred went beyond testing for glucose and developed other strips for testing levels of key indicators of disease. Once they achieved success with a number of different test strips, they turned their attention to combining more than one test on a single strip.”

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Thumbnail Image: A physician examining a urine flask. Oil painting by Gerard Thomas.. Credit: Wellcome Collection. Public Domain Mark Thomas, Gérard, 1663-1720.