David R. Ballerini

Exploration of microfluidic devices based on multi-filament threads and textiles: A review.

In this paper, we review the recent progress in the development of low-cost microfluidic devices based on multifilament threads and textiles for semi-quantitative diagnostic and environmental assays. Hydrophilic multifilament threads are capable of transporting aqueous and non-aqueous fluids via capillary action and possess desirable properties for building fluid transport pathways in microfluidic devices. Thread can be sewn onto various support materials to form fluid transport channels without the need for the patterned hydrophobic barriers essential for paper-based microfluidic devices. Thread can also be used to manufacture fabrics which can be patterned to achieve suitable hydrophilic-hydrophobic contrast, creating hydrophilic channels which allow the control of fluids flow. Furthermore, well established textile patterning methods and combination of hydrophilic and hydrophobic threads can be applied to fabricate low-cost microfluidic devices that meet the low-cost and low-volume requirements. In this paper, we review the current limitations and shortcomings of multifilament thread and textile-based microfluidics, and the research efforts to date on the development of fluid flow control concepts and fabrication methods. We also present a summary of different methods for modelling the fluid capillary flow in microfluidic thread and textile-based systems. Finally, we summarized the published works of thread surface treatment methods and the potential of combining multifilament thread with other materials to construct devices with greater functionality. We believe these will be important research focuses of thread- and textile-based microfluidics in future.

Red blood cell transport mechanisms in polyester thread-based blood typing devices

AbstractA recently developed blood typing diagnostic based on a polyester thread substrate has shown great promise for use in medical emergencies and in impoverished regions. The device is easy to use and transport, while also being inexpensive, accurate, and rapid. This study used a fluorescent confocal microscope to delve deeper into how red blood cells were behaving within the polyester thread-based diagnostic at the cellular level, and how plasma separation could be made to visibly occur on the thread, making it possible to identify blood type in a single step. Red blood cells were stained and the plasma phase dyed with fluorescent compounds to enable them to be visualised under the confocal microscope at high magnification. The mechanisms uncovered were in surprising contrast with those found for a similar, paper-based method. Red blood cell aggregates did not flow over each other within the thread substrate as expected, but suffered from a restriction to their flow which resulted in the chromatographic separation of the RBCs from the liquid phase of the blood. It is hoped that these results will lead to the optimisation of the method to enable more accurate and sensitive detection, increasing the range of blood systems that can be detected. Graphical AbstractAgglutinated FITC stained A+ blood on anti-A antibody treated thread. Sheet like structures composed of agglutinated RBCs can be seen, wrapped around fibres and occupying the spaces between them

Thread as a Low-Cost Biodiagnostic Substrate

State of the art diagnostics taken for granted in the developed world are prohibitively expensive to countries which are economically challenged. Development of inexpensive diagnostic devices which are affordable to 3 rd world markets is therefore important for improving global public health.

Thread as a substrate for low-cost point-of-care diagnostics

This study presents new applications of thread-based microfluidic systems in chemical and biochemical diagnostics. Our recent reports have demonstrated the capability of fabricating low-cost microfluidic devices using ubiquitous multifilament materials such as threads. The gaps between fibres in threads provide capillary wicking channels for liquid transport; therefore, liquid can penetrate along threads without the need of external forces. The new threadbased system, combined with the cheap dosing tools, is capable of easily and rapidly semi-quantifying the concentration of analytes in human body fluids. The utility of this system is further extended for the rapid and easy blood grouping with only small amount of whole blood (~ 2 µL for ABO blood typing), which is an essential test before blood transfusion. These low-cost and portable microfluidic devices are easy to fabricate, simple to use, and do not require powers such as electricity; thus providing a desirable analytical platform for point-of-care applications.