A frugal microfluidic pump

Design and numerical study of a bidirectional acoustic microfluidic pump enabled by microcantilever arrays

Microfluidics offers a versatile and promising platform for various applications in biomedical and other fields, boasting cost-effectiveness, rapid analysis time, and a compact equipment footprint. However, achieving controlled and versatile microfluidic motion within implantable devices presents a significant challenge. In this study, we propose a novel bidirectional micro-pump design that leverages two sharp-edge microcantilever arrays, driven by ultrasound, to enable selective flow direction by manipulating the ultrasound frequency. Through systematic numerical simulation, we demonstrate the feasibility of this design and further optimize its performance through comprehensive parametric analysis. This work provides valuable guidance for the practical development of sharp-edge-based acoustic micro-pumps, particularly for potential implantable applications such as controlled drug release and in vivo sampling for advanced diagnostics.

Programmable Gravity Self-Driven Microfluidic Chip for Point-of-Care Multiplied Immunoassays

Point-of-care testing (POCT) is experiencing a groundbreaking transformation with microfluidic chips, which offer precise fluid control and manipulation at the microscale. Nevertheless, chip design or operation for existing platforms is rather cumbersome, with some even heavily depending on external drivers or devices, impeding their broader utilization. This study develops a unique programmable gravity self-driven microfluidic chip (PGSMC) capable of simultaneous multi-reagent sequential release, multi-target analysis, and multi-chip operation. All necessary reagents are introduced in a single step, and the process is initiated simply by flipping the PGSMC vertically, eliminating the need for additional steps or devices. Additionally, it demonstrates successful immunoassays in less than 60 min for antinuclear antibodies testing, compared to more than 120 min by traditional methods. Assessment using 25 clinically diagnosed cases showcases remarkable sensitivity (96%), specificity (100%), and accuracy (99%). These outcomes underscored its potential as a promising platform for POCT with high accuracy, speed, and reliability, highlighting its capability for automated fluid control.

Microfluidic pumps for cell sorting

Microfluidic cell sorting has shown promising advantages over traditional bulky cell sorting equipment and has demonstrated wide-reaching applications in biological research and medical diagnostics. The most important characteristics of a microfluidic cell sorter are its throughput, ease of use, and integration of peripheral equipment onto the chip itself. In this review, we discuss the six most common methods for pumping fluid samples in microfluidic cell sorting devices, present their advantages and drawbacks, and discuss notable examples of their use. Syringe pumps are the most commonly used method for fluid actuation in microfluidic devices because they are easily accessible but they are typically too bulky for portable applications, and they may produce unfavorable flow characteristics. Peristaltic pumps, both on- and off-chip, can produce reversible flow but they suffer from pulsatile flow characteristics, which may not be preferable in many scenarios. Gravity-driven pumping, and similarly hydrostatic pumping, require no energy input but generally produce low throughputs. Centrifugal flow is used to sort cells on the basis of size or density but requires a large external rotor to produce centrifugal force. Electroosmotic pumping is appealing because of its compact size but the high voltages required for fluid flow may be incompatible with live cells. Emerging methods with potential for applications in cell sorting are also discussed. In the future, microfluidic cell sorting methods will trend toward highly integrated systems with high throughputs and low sample volume requirements.

Multi-objective optimisation of polymerase chain reaction continuous flow systems

A surrogate-enabled multi-objective optimisation methodology for a continuous flow Polymerase Chain Reaction (CFPCR) systems is presented, which enables the effect of the applied PCR protocol and the channel width in the extension zone on four practical objectives of interest, to be explored. High fidelity, conjugate heat transfer (CHT) simulations are combined with Machine Learning to create accurate surrogate models of DNA amplification efficiency, total residence time, total substrate volume and pressure drop throughout the design space for a practical CFPCR device with sigmoid-shape microfluidic channels. A series of single objective optimisations are carried out which demonstrate that DNA concentration, pressure drop, total residence time and total substrate volume within a single unitcell can be improved by up to [Formula: see text]5.7%, [Formula: see text]80.5%, [Formula: see text]17.8% and [Formula: see text]43.2% respectively, for the practical cases considered. The methodology is then extended to a multi-objective problem, where a scientifically-rigorous procedure is needed to allow designers to strike appropriate compromises between the competing objectives. A series of multi-objective optimisation results are presented in the form of a Pareto surface, which show for example how manufacturing and operating cost reductions from device miniaturisation and reduced power consumption can be achieved with minimal impact on DNA amplification efficiency. DNA amplification has been found to be strongly related to the residence time in the extension zone, but not related to the residence times in denaturation and annealing zones.