Open-source spring-driven syringe pump with 3D-printed components for microfluidic applications.

The operation of microfluidic devices requires precise and constant fluid flow. Microfluidic systems in low-resource settings require a portable, inexpensive, and electricity-free pumping approach due to the rising demand for microfluidics in point-of-care testing (POCT). Open-source alternatives, employing 3D printing and motors, offer affordability. However, using motors require electrical power, which often relies on external sources, hindering the on-site use of open-source pumps. This study introduces a spring-driven, 3D-printed syringe pump, eliminating the need for an external power source. The syringe pump is operated by the flat spiral spring's torque. By manually winding up the mainspring, the syringe pump can be operated without electricity. Various flow rates can be achieved by utilizing different syringe sizes and choosing the right gear combinations. All the parts of the syringe pump can be fabricated by 3D printing, requiring no additional components that require electricity. It operates by winding a mainspring and is user-friendly, allowing flow rate adjustments by assembling gears that modulate syringe plunger pushing velocity. The fabrication cost is $25-30 and can be assembled easily by following the instructions. We expect that the proposed syringe pump will enable the utilization of microfluidic technologies in resource-limited settings, promoting the adoption of microfluidics. Detailed information and results are available in the original research paper (https://doi.org/10.1016/j.snb.2024.135289).

Pressed Lateral Flow Assay Strips for Flow Delay-Induced Signal Enhancement in Lateral Flow Assay Strips.

This paper proposes that the signal intensity of a lateral flow assay (LFA) strip can be increased by pressing the top of the strip, effectively reducing its flow rate. The reduced flow rate allows more time for antigen-antibody interactions to occur, resulting in increased signal intensity and an improved detection limit. To assess the potential of the pressed LFA (pLFA) strip, C-reactive protein (CRP) diluted in phosphate-buffered saline (PBS) and serum is detected, affording signal enhancement and a lowered limit of detection. Additionally, to show that the signal enhancement by pressure-induced flow delay applies to existing LFA products, commercially available COVID-19 antigen test strips are pressed, and signal enhancement is observed. Lastly, we show that the signal intensity of COVID-19 LFA kits can be increased by approximately two-fold at maximum by applying pressure on top of the manufactured product. This study suggests that pressed LFA strips can be used to reduce the chances of determining ambiguous signals as false-negative results and can potentially improve the detection sensitivity. Supplementary Information: The online version contains supplementary material available at 10.1007/s13206-022-00085-w.