Pumpless Microflow Cytometry Enabled by Viscosity Modulation and Immunobead Labeling

Computational Hyperspectral Microflow Cytometry

Miniaturized flow cytometry has significant potential for portable applications, such as cell-based diagnostics and the monitoring of therapeutic cell manufacturing, however, the performance of current techniques is often limited by the inability to resolve spectrally-overlapping fluorescence labels. Here, the study presents a computational hyperspectral microflow cytometer (CHC) that enables accurate discrimination of spectrally-overlapping fluorophores labeling single cells. CHC employs a dispersive optical element and an optimization algorithm to detect the full fluorescence emission spectrum from flowing cells, with a high spectral resolution of ≈3 nm in the range from 450 to 650 nm. CHC also includes a dedicated microfluidic device that ensures in-focus imaging through viscoelastic sheathless focusing, thereby enhancing the accuracy and reliability of microflow cytometry analysis. The potential of CHC for analyzing T lymphocyte subpopulations and monitoring changes in cell composition during T cell expansion is demonstrated. Overall, CHC represents a major breakthrough in microflow cytometry and can facilitate its use for immune cell monitoring.

Towards practical sample preparation in point-of-care testing: user-friendly microfluidic devices

Microfluidic technologies offer a number of advantages for sample preparation in point-of-care testing (POCT), but the requirement for complicated external pumping systems limits their wide use. To facilitate sample preparation in POCT, various methods have been developed to operate microfluidic devices without complicated external pumping systems. In this review, we introduce an overview of user-friendly microfluidic devices for practical sample preparation in POCT, including self- and hand-operated microfluidic devices. Self-operated microfluidic devices exploit capillary force, vacuum-driven pressure, or gas-generating chemical reactions to apply pressure into microchannels, and hand-operated microfluidic devices utilize human power sources using simple equipment, including a syringe, pipette, or simply by using finger actuation. Furthermore, this review provides future perspectives to realize user-friendly integrated microfluidic circuits for wider applications with the integration of simple microfluidic valves.

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

The development of passively driven microfluidic labs on chips has been increasing over the years. In the passive approach, the microfluids are usually driven and operated without any external actuators, fields, or power sources. Passive microfluidic techniques adopt osmosis, capillary action, surface tension, pressure, gravity-driven flow, hydrostatic flow, and vacuums to achieve fluid flow. There is a great need to explore labs on chips that are rapid, compact, portable, and easy to use. The evolution of these techniques is essential to meet current needs. Researchers have highlighted the vast potential in the field that needs to be explored to develop rapid passive labs on chips to suit market/researcher demands. A comprehensive review, along with patent analysis, is presented here, listing the latest advances in passive microfluidic techniques, along with the related mechanisms and applications.

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

Microfluidics offers great potential for biomedical applications, but the complexity, inconvenience, and low pumping equipment accessibility of operating microfluidic devices have limited their widespread use. Here we describe an open-source, programmable smart (OS) pipette as an easy-to-use, simple, handheld microfluidic pump that overcomes the major limitations of previous commercial- or research-level pumps for microfluidics. The OS pipette pumps fluid into a microfluidic device by precisely controlling the position of the plunger of a positive-displacement micropipette with stepper motor control. The intuitive pumping mechanism of the OS pipette enables the novel features of simple fabrication, straightforward device operation, and precise, predictable, and programmable flow-rate generation as an open-source pumping tool. Controlling the OS pipette using an open-source microcontroller board not only allows straightforward generation of constant flow rates with simple source code commands, but also permits varying flow rates to be programmed (including stepwise increase and decrease of the flow rate over time, and flow-rate pulse generation). We successfully validate the OS pipette's capabilities for portable microfluidic cell separation and counting. The OS pipette has promise as a rapidly evolving and potentially transformative pumping tool that freely allows unrestricted use, distribution, reproduction, and modification even by non-expert users, and further enables diverse usages, even beyond microfluidics.