A complete blood count (CBC) is a basic and important diagnostic
procedure in pathological laboratories [1]. Red blood cell (RBC)
concentration, white blood cell (WBC) concentration, and percentages
ofthe subpopulations of WBCs (neutrophils, lymphocytes, and
monocytes), determined by a CBC, are the major parameters corresponding
to a specific disease or disorder [2–4]. The complete blood
count (CBC) is traditionally performed with a hemocytometer, a
device designed for cell counting comprising a microscopic glass
slide with a rectangular indentation that creates a chamber 100 m
deep, under a conventional optical microscope. Hemocytometry is
a time-consuming process as identification and counting of cells
are conducted manually [5,6]. This manual method therefore suffers
from low throughput, subjective operator errors, and high risk
for operator’s infection. In contrast, the impedance [7] or flowcytometry
[8] based automated electrical or optical cell counting
approaches provides quick and accurate results. Using hydrodynamic
focusing devices, these automated modalities measure
direct current impedance, radio frequency impedance, forward
laser scattering, and side laser scattering of the suspended cells
in a specimen at the micro-orifice or interrogation site to provide
information on the size, internal complexity, surface morphology,
and granularity of the cells. These techniques evolved from surface
chemistry (e.g., fluorescence or nanoparticle labeling), and
have become the gold standards in the fields of clinical diagnostic
practice and trials. However, the high cost of instrumentation
and maintenance, bulky size, and high-level of operator training
severely limit their use for most research studies.
There is an emerging demand for a compact point-of-care (POC)
system for determining CBC withoutthe use of a label. For instance