Do I have cancer? Is my unborn child in trouble? University of Wisconsin- Madison biomedical engineer Nimmi Ramanujam believes that the millions of women who face these questions each year deserve more accurate answers than those afforded by today’s diagnostic technologies. Consider breast biopsies. Doctors sometimes miss the tumor cells they’re trying to sample, so Ramanujam has developed a device that can help guide a biopsy needle to just the right spot. An optical fiber threaded through the needle shines light of different wavelengths on cells as the needle’s tip; molecules in cancer cells respond by fluorescing in characteristic ways, and sensors register the fluorescence. Ramanujam and her colleagues are already testing the technology in patients undergoing breast cancer surgery and plan to test it in patients undergoing breast biopsy within the next year. A cervical-cancer detector she began developing as a graduate student uses a similar approach; it is now in large-scale human trials. Ramanujam is also harnessing light to non-invasively monitor how well oxygen is getting to fetuses, an important- and currently un-measurable- indicator of when emergency cesarean sections are needed. With Ramanujam’s help, those babies will be born into a world where medical questions get better answers.