As food regulations become more stringent and medicine requires more accurate methods of diagnosing a patient's condition, there is an increasing need for non-invasive technology which can supply precise information about specific biological conditions. Quentin Cooper talks to Professor Tony Turner about biosensors - a developing technology used in medicine, the environment, public health and defence-and asks what new uses for them remain to be developed. Producer John Watkins. E-MAIL: [email address removed]