Simplified White Blood Cell Differential: An Inexpensive, Smartphone- and Paper-Based Blood Cell Count

Abstract

Sorting and measuring blood by cell type is extremely valuable clinically and provides physicians with key information for diagnosing many different disease states including: leukemia, autoimmune disorders, bacterial infections, etc. Despite the value, the present methods are unnecessarily costly and inhibitive particularly in resource poor settings, as they require multiple steps of reagent and/or dye additions and subsequent rinsing followed by manual counting using a hemocytometer, or they require a bulky, expensive equipment such as a flow cytometer. While direct on-paper imaging has been considered challenging, paper substrate offers a strong potential to simplify such reagent/dye addition and rinsing. In this work, three-layer paper-based device is developed to automate such reagent/dye addition and rinsing via capillary action, as well as separating white blood cells (WBCs) from whole blood samples. Direct on-paper imaging is demonstrated using a commercial microscope attachment to a smartphone coupled with a blue LED and 500 nm long pass optical filter. Image analysis is accomplished using an original MATLAB code, to evaluate the total WBC count, as well as differential WBC count, i.e., granulocytes (primarily neutrophils) vs. agranulocytes (primarily lymphocytes). Only a finger-prick of whole blood is required for this assay. The total assay time from finger-prick to data collection is under five minutes. Comparison with a hemocytometry-based manual counting corroborates the accuracy and effectiveness of the proposed method. This approach could be potentially used to help make blood cell counting technologies more readily available, especially in resource poor, point-of-care settings.

Immunomagnetic leukocyte differential in whole blood on an electronic microdevice

“…Recently, alternative methods have been developed to address the limitations of the existing instrumentation by using machine learning for classification from cell images, 22 using refractive index tomography, 23 Raman spectroscopy, 24 miniaturized laser setups with fluorescent dyes [25][26][27][28] or lowcost systems such as smartphone-coupled paper-based assays 29,30 and microfluidic platforms with impedance measurements [31][32][33] and capture arrays. 34,35 However, these works were often unable to process the samples with erythrocytes present due to the overwhelming interference they would cause.…”

Establishment of pediatric reference intervals for complete blood count parameters in capillary blood in Beijing

“…Complete blood count (CBC) is one of the routine blood tests used for clinical diagnosis, disease treatment, and health assessment 1 . Comparing test results with the appropriate reference intervals (RIs) is the first step in the clinical interpretation of these laboratory results 2 .…”

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Complete blood count (CBC) is one of the routine blood tests used for clinical diagnosis, disease treatment, and health assessment. 1 Comparing test results with the appropriate reference intervals (RIs) is the first step in the clinical interpretation of these laboratory results. 2 However, there are no consensus-based CBC RIs for children, and many medical institutions still apply RIs determined from adults, from children in other countries, or from children in a different age range.

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A Novel Paper-Based Cytometer for the Detection and Enumeration of White Blood Cells According to their Immunophenotype

“…40 Analogous paper-based devices designed to enumerate WBCs operate by "WBC trapping" or retaining WBCs based on their size in devices that only incorporate vertical flow and require off-chip labeling. [41][42][43] While this design may be adequate for some applications (e.g., total WBC count), the restriction to vertical flow and lack of assay integration greatly limits their potential applications and complicates user operation. 24 The inclusion of lateral, directed flow in patterned paper devices allows for many more opportunities in paper-based device design, including the ability to incorporate complex sample-processing (e.g., selective lysis), multiplexing, and to allow for proper mixing of any affinity-based labeling reagents in situ.…”