Abstract: An apparatus for monitoring a level of a chemical species in a body fluid includes a fluid collection layer adapted for receiving the body fluid. The fluid collection layer is dry prior to being brought into contact with the body fluid. A catalyst is provided in, on, or near the fluid collection layer so as to be in contact with the body fluid in the fluid collection layer. The catalyst facilitates a reaction of the chemical species in the body fluid. An indicator, responsive to the reaction of the chemical species, is also provided in, on, or near the fluid collection layer. A characteristic of the indicator changes in response to the reaction of the chemical species, thereby indicating the level of the chemical species in the body fluid. This apparatus can be used, for example, to monitor the level of lactate in perspiration during activities, such as exercise or other athletic exertions.

Abstract: The present disclosure relates to an on-line lactate sensor arrangement. The sensor arrangement includes a lactate sensor, a catheter for withdrawing a test sample, and a first fluid flow line provided fluid communication between the lactate sensor and the catheter. The sensor arrangement also includes a source of sensor calibration and anticoagulant solution, and second fluid flow line providing fluid communication between the source of sensor calibration and anticoagulant solution and the lactate sensor.