Embedded piezoresistive microcantilever (EPM) sensors were used to detect the presence of the compound estrogen in water samples. The sensor was fabricated with a host material hydrogel (Hypol) functionalized with estrogen antibody. This sensor was able to detect 1 ppm of estrogen in water, responding almost immediately to the estrogen addition, with a full sensor response (saturation) occurring after two minutes of exposure.