The development of a submicron optical fiber `supertip' has provided advantages over previously produced submicron tips, such as facilitating insertion of these sensors into cells while minimizing damage to the cell membrane. Fiber optic ion correlation-based nanosensors for sodium, potassium and chloride employing these `supertips' have been applied to the monitoring of ion concentrations in single mouse oocytes. These sensors have also been used to monitor the effect of an ion channel-blocking agent. In order to address the challenge associated with single-cell simultaneous measurement of multiple analytes, the use of submicron optical fiber multiprobes has been explored.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.