Sensor clip assembly for an optical monitoring system

A system for optically monitoring blood, the system comprising:

• a blood chamber comprising a viewing window and a chamber body;
• a sensor clip assembly, configured to be fastened to the blood chamber, the sensor clip 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;
• and
• the external computing device, configured to display the results of the calculations performed by the microcontroller to a user;
• 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.

A method for optically monitoring extracorporeal blood using a sensor clip assembly attached to a blood chamber, the method comprising:

• in a first time interval, turning on, by a processor of the sensor clip assembly, a first emitter of the sensor clip assembly corresponding to light of a first wavelength and generating a first detected signal at a first photodetector of the sensor clip assembly corresponding to detected light of the first wavelength that has passed through extracorporeal blood in the blood chamber;
• converting, by a signal conditioning circuit, a first current corresponding to the first detected signal to a first voltage;
• and applying, by the signal conditioning circuit, a first gain to the first voltage;
• converting, by an analog-to-digital converter of the sensor clip assembly, the first voltage with the first gain applied to a first digital signal, wherein the first digital signal corresponds to a hemoglobin level of extracorporeal blood in a blood chamber to which the sensor clip assembly is fastened;
• in a second time interval, turning on, by the processor, a second emitter of the sensor clip assembly corresponding to light of a second wavelength and generating a second detected signal at a second photodetector of the sensor clip assembly corresponding to detected light of the second wavelength that has passed through extracorporeal blood in the blood chamber;
• converting, by the signal conditioning circuit, a second current corresponding to the second detected signal to a second voltage;
• and applying, by the signal conditioning circuit, a second gain to the second voltage;
• converting, by the analog-to-digital converter, the second voltage with the second gain applied to a second digital signal, wherein the second digital signal corresponds to a water concentration level of the extracorporeal blood in the blood chamber;
• calculating, by the processor, a hematocrit value corresponding to the extracorporeal blood in the blood chamber based on a ratio between the first and second digital signals;
• and
• transmitting the calculated hematocrit value to an external computing device;
• wherein the method further comprises:
• in response to determining an insufficient number of bits on the analog-to-digital converter being activated, adjusting a resolution level for signals received by the analog-to-digital converter by increasing the first gain and/or the second gain;
• and
• wherein operation of the first emitter and the second emitter is synchronized with operation of the signal conditioning circuit with respect to the first time interval and the second time interval, respectively, 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.