Pumpless Microflow Cytometry Enabled by Viscosity Modulation and Immunobead Labeling

Abstract

Major challenges of miniaturizing flow cytometry include obviating the need for bulky, expensive, and complex pump-based fluidic and laser-based optical systems while retaining the ability to detect target cells based on their unique surface receptors. We addressed these critical challenges by (i) using a viscous liquid additive to control flow rate passively, without external pumping equipment, and (ii) adopting an immunobead assay that can be quantified with a portable fluorescence cell counter based on a blue light-emitting diode. Such novel features enable pumpless microflow cytometry (pFC) analysis by simply dropping a sample solution onto the inlet reservoir of a disposable cell-counting chamber. With our pFC platform, we achieved reliable cell counting over a dynamic range of 9-298 cells/μL. We demonstrated the practical utility of the platform by identifying a type of cancer cell based on CD326, the epithelial cell adhesion molecule. This portable microflow cytometry platform can be applied generally to a range of cell types using immunobeads labeled with specific antibodies, thus making it valuable for cell-based and point-of-care diagnostics.

Computational Hyperspectral Microflow Cytometry

“…The experimental results are in good agreement with simulation results, which show that the Weissenberg number (Wi = 𝜆 ⋅ ̇𝛾 ≈ 19.2) [39,40] and the gradient of the first normal stress (N 1 ) are higher at C PEO = 2.0 wt% than other conditions (Figure 4c), where Wi is defined as the product of the relaxation time (𝜆) and the shear rate ( ̇𝛾), and N 1 is defined as 𝜎 xx − 𝜎 yy . The elastic force (F E ) can be scaled as [41,42] F E ∝ d 3 ∇N 1 (6) where d is the particle diameter. These simulation results demonstrate that particles can migrate rapidly toward the center plane at the optimal concentration of C PEO = 2.0 wt%, at which the following experiments were performed.…”

“…This has led to a growing interest in miniaturizing flow cytometry to expand the range of applications. [1][2][3][4][5][6][7][8][9][10] Despite significant progress in miniaturizing the fluidics system of flow cytometry through sheathless focusing techniques, [11][12][13][14][15][16] its optical system still remains challenging to miniaturize.…”

Advances in passively driven microfluidics and lab-on-chip devices: a comprehensive literature review and patent analysis

“…It also required the adoption of an immune bead assay, which was quantied with a portable uorescence cell counter based on a blue-light-emitting diode. 180 Moonen et al investigated capillary-based passive pumping for optimized neuronal cell trapping across a microsieve with gentle velocity proles and high survival rates. 181 Reports on capillary-based passive pumping in microuidics are summarised in Table 4.…”

An open-source programmable smart pipette for portable cell separation and counting

“…A miniaturized uorescence microscope was fabricated by simply assembling a laser diode (488 nm; DTR Laser, United States), a longpass lter with a cut-on wavelength of 515 nm (Omega Optical, Inc., United States), a 2 objective lens (Edmund Optics, Inc., United States), and a CMOS sensor (FLIR, Inc., Canada) in a 3D-printed housing, as described before. 9,21 The eld-of-view of the miniaturized microscope was 1.446 mm  0.579 mm, which is large enough to capture the region of interrogation, the outlet channel region (400 mm in width) of the sheathless focuser.…”

“…Intensive efforts have been devoted to developing such pumping methods that can be categorized into passive and active approaches, depending on power usage. [14][15][16][17][18][19][20][21][22][23][24][25][26] Passive approaches can simply pump uid samples without power consumption using pressure gradients generated by surface tension, 14 pressure head, 15,16 degassed gas-permeable materials, 17,18 absorbent, 19,20 capillary action, 21,22 pumping lid, 23 smart pipette, 24,25 and osmosis. 26 These passive principles are easy to use without the need for external equipment, and some of them can be embedded directly into microuidic devices, thus resulting in the miniaturization of entire microuidic systems.…”