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

13 April 2022, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


Total and differential white blood cell (WBC) counts are vital metrics used routinely by clinicians to aid in the identification of diseases. However, the equipment necessary to perform WBC counts restricts their operation to centralized laboratories, greatly limiting their accessibility. Established solutions for the development of point-of-care assays, namely lateral flow tests and paper-based microfluidic devices, are inherently limited in their ability to support the detection of WBCs—the pore sizes of materials used to fabricate these devices (e.g., membranes or chromatography papers) do not permit passive WBC transport via wicking. Herein, we identify a material capable of the unimpeded transport of WBCs in both lateral and vertical directions: a coffee filter. Through in situ labeling with an enzyme-labeled affinity reagent, our paper-based cytometer detects WBCs according to their immunophenotype. Using two cultured leukocyte lines (Jurkat D1.1 T cells and MAVER-1 B cells), we demonstrate the specific, colorimetric enumeration of each target cell population across the expected physiological range for total lymphocytes, 1000–4000 cells µL-1. Additionally, we highlight a potential application of this type of device as a screening tool for detecting abnormal cell counts outside the normal physiological range and in sub-classes of cell types, which could aid in the identification of certain diseases (e.g., CD4+ T lymphocytes, an important biomarker for HIV disease/AIDS). These results pave the way for a new class of paper-based devices—those capable of controlled white blood cell transport, labeling, capture, and detection—thus expanding the opportunities for low-cost, point-of-care cytometers.


paper-based microfluidic devices
point of care
porous materials
white blood cell counts
paper analytical device

Supplementary materials

Supporting Information for Murray et al. (Paper Cytometer)
Materials and Methods. Tables and figures depicting results from the material screen, figures and tables depicting results and analyses from the porosimetry characterization of select materials, flow cytometry results, the process for image analyses, results from statistical analyses, full calibration curves for enumerating T and B cells with and without shaded regions indicating the potential for semi- quantitative visual identification, full calibration curves for enumerating CD4+ T lymphocytes, calibration curve parameters for each assay, and results from an additional fluorescent cell mapping experiment. Supplementary references are also included.


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.