Microscopy for the Identification of Oxyhemoglobin Species in Red Blood Cells

This novel invention combines a Solid Immersion Lens (SIL) microscope with the Surface Plasmon Resonance (SPR) effect to achieve precise measurement of refractive index of a target, with high spatial resolution. When used to examine Red Blood Cells (RBC) at multiple wavelengths, the refractive index measurement yields the variation in oxygen content of hemoglobin across a 2D array of pixels, while also imaging the RBCs. The simultaneous measurement of refractive index and optical imaging of RBCs is extremely valuable where oxygen saturation level also affects the shape of the RBCs, such as in sickle cell anemia.

Background:

Current methods of measuring blood oxygen levels suffer from either a lack of high accuracy, such as with pulse oximeters, or require blood being taken to a lab for higher accuracy analysis. Currently, there are no devices available that could examine blood at the bed side with high accuracy. Furthermore, neither the pulse oximeter nor the co-oximeter can examine the blood cell size or shape in-vivo, and the higher accuracy methods.
 

Applications:

• Emergency room & bed side analysis of arterial or veinous blood oxygen levels and blood cell shape and size with high precision
• Rapid analysis of various species of hemoglobin in the RBCs, and imaging the variations at the sub-cellular level

Advantages:

• Measurement of refractive index of hemoglobin in RBCs and its corresponding relationship with oxygen bonding states
• High resolution optical imaging of RBCs and refractive index map of individual RBCs in one simple apparatus
• Parameters of interest measured directly; no complicated numerical procedures required
• Accounts for changes in refractive index of hemoglobin due to change in oxygen saturation level and changes in concentration of hemoglobin without regard to pathlength, which other techniques cannot do

Status: issued U.S. patent #9,072,473