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Sensor clip assembly for an optical monitoring system

  • US 9,801,993 B2
  • Filed: 11/17/2011
  • Issued: 10/31/2017
  • Est. Priority Date: 11/17/2010
  • Status: Active Grant
First Claim
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1. A sensor clip assembly for optically monitoring extracorporeal blood flowing through a blood chamber, the sensor clip assembly comprising:

  • a housing;

    a first photodetector, configured to, in a first time interval, generate a first current corresponding to a first detected signal based on light of a first wavelength from a first emitter of the sensor clip assembly that has passed through extracorporeal blood in the blood chamber;

    a second photodetector, configured to, in a second time interval, generate a second current corresponding to a second detected signal based on light of a second wavelength from a second emitter of the sensor clip assembly that has passed through extracorporeal blood in the blood chamber;

    a signal processing unit within the housing, comprising a processor and a signal conditioning circuit, the signal conditioning circuit being configured to convert the first current to a first voltage and apply a first gain to the first voltage, and configured to convert the second current to a second voltage and apply a second gain to the second voltage; and

    an analog-to-digital converter, configured to convert the first voltage with the first gain applied to a first digital signal and to convert the second voltage with the second gain applied to a second digital signal, wherein the first digital signal corresponds to a hemoglobin level of the extracorporeal blood and the second digital signal corresponds to a water concentration level of the extracorporeal blood;

    wherein the processor is configured to synchronize operation of the signal conditioning circuit with operation of the first emitter and the second emitter of the sensor clip assembly such that the first gain is only applied to the first voltage while the first emitter is on and the second gain is only applied to the second voltage while the second emitter is on, and to calculate a hematocrit value based on a ratio between the first and second digital signals;

    wherein the sensor clip assembly further comprises;

    an output port configured to facilitate transmission of the calculated hematocrit value to an external computing device;

    wherein the signal processing unit is further configured to, in response to determining an insufficient number of bits on the analog-to-digital converter being activated, adjust a resolution level for signals received by the analog-to-digital converter by increasing the first gain and/or the second gain.

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