Pump Arrangement in Continuous Analyte Monitoring
A method of monitoring an analyte (such as, e.g., glucose) including the following steps: diffusing the analyte from a sampling location into a sensing fluid within a sensing chamber; detecting a concentration of the analyte in the sensing fluid; moving flushing fluid into the sensing chamber and simultaneously removing sensing fluid from the sensing chamber; permitting the flushing fluid to remain in the sensing chamber without flowing for a dwell time; removing the flushing fluid from the sensing chamber after the dwell time expires; and, after removing the flushing fluid from the sensing chamber, moving sensing fluid into the sensing chamber. The invention also includes an analyte monitoring device performing this method.
1 . A method of monitoring an analyte comprising:
diffusing the analyte from a sampling location into a sensing fluid within a sensing chamber;
detecting a concentration of the analyte in the sensing fluid;
moving flushing fluid into the sensing chamber and simultaneously removing sensing fluid from the sensing chamber;
permitting the flushing fluid to remain in the sensing chamber without flowing for a dwell time;
removing the flushing fluid from the sensing chamber after the dwell time expires; and
after removing the flushing fluid from the sensing chamber, moving sensing fluid into the sensing chamber and detecting a concentration of the analyte in the sensing fluid.
2 . The method of claim 1 wherein the dwell time is between 1 second and 30 seconds.
3 . The method of claim 1 wherein the steps of moving and removing the flushing fluid are performed by a pulsatile pump.
4 . The method of claim 1 wherein the analyte is glucose.
5 . The method of claim 1 wherein the sampling location is a subject's interstitial fluid.
6 . The method of claim 5 wherein diffusing comprises diffusing the analyte from the interstitial fluid via fluid paths formed through a stratum corneum layer of the subject's skin.
7 . The method of claim 6 further comprising forming the fluid paths through the stratum corneum.
8 . The method of claim 1 wherein the flushing fluid and the sensing fluid are the same.
9 . The method of claim 1 wherein the diffusing step comprises diffusing the analyte from the sampling location into the sensing fluid without using a dialysis membrane.
10 . The method of claim 1 wherein the flushing fluid is an aqueous buffer electrolyte solution.
11 . The method of claim 1 wherein the flushing fluid is calibration fluid, the method further comprising calibrating an analyte sensor prior to removing the flushing fluid from the sensing chamber.
12 . An analyte monitoring device comprising:
a sampling member;
a sensing chamber in fluid communication with the sampling member;
an analyte sensor in fluid contact with the sensing chamber; and
a pump programmed to move flushing fluid into the sensing chamber and remove sensing fluid from the sensing chamber so that the flushing fluid remains in the sensing chamber without flowing for a dwell time.
13 . The device of claim 12 wherein the sampling member comprises a fluid path.
14 . The device of claim 12 wherein the sampling member comprises a tissue piercing element.
15 . The device of claim 12 wherein the pump comprises a pulsatile pump.