Ubiquitous sensors: when will they be here?

Chemical and biological sensors are necessary for making continuous measurements in a variety of settings. A typical sensor comprises a molecular recognition element coupled to a transducer. Binding of the analyte to the recognition element leads to signal transduction. Many sensors employ an extrinsic label to indirectly signal the presence of the analyte. Label-free methods have the advantage that no exogenous reagents are required, making the sensor simple to implement. New label-free transduction methods should facilitate the wider application of sensors. Challenges remain with reproducibility, calibration, and manufacturability. Solving these problems will require an interdisciplinary collaboration between chemists, biologists, biochemists, and engineers. An article by Sailor and co-workers in this issue takes a significant step toward this goal. The availability of inexpensive sensors for wide-scale deployment will transform society in terms of health care as well as home and workplace monitoring.