The Nano-Biosensing program, part of the Engineering Biology and Health cluster at the National Science Foundation (NSF), seeks fundamental engineering research proposals on devices and methods for measuring and quantifying biological analytes. Proposals that incorporate emerging nanotechnology methods are encouraged. Key areas of interest include multi-purpose sensor platforms, novel transduction principles, and nano-biosensors that enable measurement of biological phenomena. Proposals should clearly identify the problem to be solved, describe the superiority of the proposed approach, and articulate the societal benefit. Sensor designs that yield reliable, reproducible measurements are preferred over incremental improvements. The typical award size is approximately $100,000 per year, with a duration of one to three years. Projects related to water quality may be jointly supported with the Environmental Engineering program, while photonic nanosensors with medical applications should be submitted to the Biophotonics program. The Nano-Biosensing program does not support imaging applications.