Figure 4

Schematic of the two paper test strips and components. For the HE4 test strip (top), the sandwich assay captures the biomarker in the middle at the test line. The control line is generated when excess reporter binds. For the creatinine test strip, a two reagent system is used to generate a colorimetric reaction with creatinine from light to dark purple. The intensity of the purple color (bottom) indicates the amount of creatinine. The two strips are placed in a scanner or cassette for the cell phone to analyze.