Label‐free somatic cell cytometry in raw milk using acoustophoresis

Abstract

A microfluidic system for cell enumeration in raw milk was developed. The new method, preconditions the milk sample using acoustophoresis that removes lipid particles which are larger than a few micrometers. The acoustophoretic preprocessing eliminates the need for conventional sample preparation techniques, which include chemical solvents, cell labeling and centrifugation, and facilitates rapid cell enumeration using microscopy or coulter counter measurements. By introducing an acoustic standing wave with three pressure nodes in a microchannel at the same time as the milk sample is laminated to the channel center, lipids are acoustically driven to the closest pressure antinode at each side of the channel center and the cells in the milk sample are focused in the central pressure node. The extracted center fraction with cells becomes sufficiently clean from lipid vesicles to enable enumeration of somatic cells without any labeling step either by direct light microscopy or by coulter counting. Obtained lipid free milk fractions clearly revealed the cell fraction when analyzed by Coulter Counting.

The intersection of flow cytometry with microfluidics and microfabrication

“…Such particles are effective for the isolation of both proteins and cells, and are envisioned to be potentially applicable to inline flow cytometry analysis in the future. This concept is also of use for applications that have cells embedded largely in low-density lipid solutions, such as detection of cells in milk 47, 48 . Both of the above approaches drive cells to the node of a standing wave, while driving the negative contrast particles or lipids to the antinode.…”

“…This makes it simple to generate many flow streams that will enable parallel analysis in the future. Using drive frequencies that match harmonics across the width of the channel and the depth of the channel enables two-dimensional focusing for precise positioning of particles 47, 48 . Acoustic focusing can be implemented in wide range of flow rates, ranging from few μL/min to several mL/min 84, 92, 93 .…”

Acoustofluidic harvesting of microalgae on a single chip

“…18,32,33 In acoustophoresis, the acoustic radiation force F is applied to cells to focus them into either pressure nodes or anti-nodes ( Fig. 1(a)) and is given by Grenvall et al 34 and Jakobsson et al…”

“…F ¼ 4pa 3 UkE sin 2kd; (1) where a is the radius of the cell, k ¼ 2p=k is the wave vector, E is the acoustic energy density, d is the distance from the wall along the axis of the standing waves, and U is the acoustic contrast factor dependent on the density and compressibility of the cells compared to the surrounding medium and is given by Grenvall et al 34 and Jakobsson et al…”

Reconfigurable acquisition system with integrated optics for a portable flow cytometer

“…4,5 The overall focus is on small, inexpensive, portable, and potentially disposable instruments that can be used by first responders, 6,7 or that can be used in resource-poor settings for applications such as the diagnosis of HIV/AIDS (CD4 counting), tuberculosis (lymphocyte counting and other techniques), and malaria (monocyte counting and other techniques). [8][9][10][11][12][13][14][15] These types of instruments can also be used for bio-surveillance applications such as monitoring the food supply, [16][17][18] monitoring water quality; [19][20][21][22][23][24][25][26][27] and they have the potential to be incorporated into remotely operated vehicles for applications such as detection of biothreats. Despite these advances, only a handful of truly portable cytometers have been demonstrated.…”