Device and method for in vitro determination of analyte concentrations within body fluids
View Patent ↗A reagentless whole-blood analyte detection system that is capable of being deployed near a patient has a source capable of emitting a beam of radiation that includes a spectral band. The whole-blood system also has a detector in an optical path of the beam. The whole-blood system also has a housing that is configured to house the source and the detector. The whole-blood system also has a sample element that is situated in the optical path of the beam. The sample element has a sample cell and a sample cell wall that does not eliminate transmittance of the beam of radiation in the spectral band.
1. An apparatus for determining the concentration of an analyte in a biological fluid sample drawn from a patient, the apparatus comprising:
a near-patient optical detection system comprising:
a source of electromagnetic radiation;
a detector;
an optical path extending between the source and the detector; and
a filter in the optical path, the filter configured to allow passage of at least one of the following wavelengths emitted by the source: about 5.25 μm, about 6.12 μm, about 7.4 μm, about 8.0 μm, about 8.45 μm, about 9.25 μm, about 10.4 μm, about 12.2 μm; and
a sample element configured for removable engagement with the optical detection system, the sample element comprising:
a reagentless sample cell configured to hold the biological fluid sample, the sample cell being located in the optical path upon engagement of the sample cell with the optical detection system, the sample cell being defined by at least one window which is transmissive of infrared radiation;
a sample supply passage extending from and in fluid communication with the sample cell;
wherein the optical detection system further comprises a sample extractor configured to draw the biological fluid sample from the patient, and the sample supply passage is configured to conduct the biological fluid sample into the sample cell.
2. The apparatus of claim 1 , further comprising a membrane in fluid communication with the sample cell, the membrane configured to filter the biological fluid sample.
3. The apparatus of claim 2 , wherein the membrane is positioned within the sample supply passage.
4. The apparatus of claim 1 , wherein the sample supply passage is configured to be engaged by the sample extractor upon engagement of the sample element with the optical detection system.
5. The apparatus of claim 1 , further comprising a flow device that induces flow of biological fluid through the sample supply passage to the sample cell.
6. The apparatus of claim 5 , wherein the flow device comprises a wicking material disposed in at least portion of the sample supply passage.
7. The apparatus of claim 1 , further comprising a housing defining a chamber, the chamber being sized and configured such that at least a portion of the sample element is situated in the optical path when the sample element is situated in the chamber.
8. The apparatus of claim 7 , further comprising a visual display mounted to the housing, the visual display provides output based on at least one signal produced by the detector.
9. The apparatus of claim 1 , wherein the source of electromagnetic radiation is capable of emitting (i) an analyte beam of radiation comprising a spectral band having a center wavelength, and (ii) a calibration beam of radiation a processor in communication with the detector, and a processor is configured to compare signals corresponding to the analyte beam and the calibration beam.
10. The apparatus of claim 1 , wherein the sample element has a sample cell wall having a non-negligible absorption of the radiation emitted from the source of electromagnetic radiation.
11. The apparatus of claim 1 , wherein the sample supply passage has a length that is greater than a width of the sample cell.