Nanometer Precise Red Blood Cell Sizing Using A Cost-effective Quantitative Dark Field Imaging System

As a part of immune system,blood interacts with every part of the body.Thus,when illness occurs,changes always show up first in the blood.Meanwhile,blood analysis is easy and relatively non-invasive,thus is very common in initial medical di-agnosis.The complete blood count(CBC)is one of the most common blood analysis methods,which gives a snapshot of a patient’s health via red blood cell counting,white blood cell counting,platelet counting and determining mean corpuscular volume,mean corpuscular hemoglobin concentration,red blood cell distribution width.At present,flow cytometry is widely used for blood detection in the hospitals.It is powerful and automated but not suitable for field use due to its huge size,complexity and the require-ment of medical professionals to operate and maintain it.Standard imaging methods could be more compact,inexpensive,and with less calibration requirements.However,due to the diffraction limit,imaging lacks the nanometer precision required to measure blood cell volumes.To address this challenge,we expand on prior work to design an optical system which utilizes Mie scattering theory to measure mean corpuscular volume(MCV),mean corpuscular hemoglobin concentration(MCHC)and red blood cell distribution width(RDW).This system is a custom-built dark-field scattering microscope with symmet-rically oblique illumination at a fixed angle to record dark-field images of diluted and sphered blood samples.Scattering intensities of each cell under three wavelengths are obtained by segmenting images via digital image processing.These scattering inten-sities are then used to determine size and hemoglobin information via Mie theory and machine learning.Validation on 90 clinical blood samples confirmed the ability to ob-tain mean corpuscular volume(MCV),mean corpuscular haemoglobin concentration(MCHC)and red cell distribution width(RDW)with high accuracy.Simulations based on historical data suggest that an instrument with the accuracy achieved in this study could be used for widespread anemia screening.