|The present invention relates to ruggedized downhole tools and sensors,
as well as uses thereof. In particular, these tools can operate under
extreme conditions and, therefore, allow for real-time measurements in
geothermal reservoirs or other potentially harsh environments. One
exemplary sensor includes a ruggedized ion selective electrode (ISE) for
detecting tracer concentrations in real-time. In one embodiment, the ISE
includes a solid, non-conductive potting material and an ion selective
material, which are disposed in a temperature-resistant electrode body.
Other electrode configurations, tools, and methods are also described.