15-year-old Jack Andraka invented a test strip that detects early signs of pancreatic cancer. This paper sensor measures the level of mesothelin (a suspected cancer biomarker) in a sample to test for the presence of cancer in a patient. Andraka coated strips of filter paper with a mixture of single-walled carbon nanotubes, which made the paper conductive, and antibodies against human mesothelin. Samples containing mesothelin were applied to these paper test strips, and the binding of mesothelin to the antibody was quantified by measuring changes in the electrical properties of the strip.