Abstract: A fluid sensor cartridge that can be used to monitor composition of constituent materials or characteristics of a sample fluid or a patient's blood. The fluid sensor cartridge can be connected in-line with a medical device during a medical treatment. The fluid sensor cartridge can utilize one or more valves, one or more channels, and one or more reservoirs to enable sampling, sensing, and calibrating of a sample fluid or a patient's blood in one container with minimal amounts of sample/blood and calibration fluid.

Abstract: Methods and apparatuses for fluid sensing system are disclosed. The method can include providing a first portion of a sample fluid in a sensing channel, holding the first portion of the sample fluid in the sensing channel for a first diffusion period, after the first diffusion period, providing a second portion of the sample fluid in the sensing channel, holding the second portion of the sample fluid in the sensing channel for a second diffusion period, and after the second diffusion period, sensing the second portion of the sample fluid in the sensing channel by a sensing element. Providing pulses of sample with intervening diffusion periods can produce more uniform analyte concentration across sensors with less overall volume of sample fluid.