Thermally-actuated microfluidic membrane valve for point-of-care applications

Microfluidics has enabled low volume biochemistry reactions to be carried out at the point-of-care.A key component in microfluidics is the microfluidic valve.Microfluidic valves are not only useful for directing flow at intersections but also allow mixtures/dilutions to be tuned real-time and even provide peristaltic pumping capabilities.In the transition from chip-in-a-lab to lab-on-a-chip,it is essential to ensure that microfluidic valves are designed to require less peripheral equipment and that they are transportable.In this paper,a thermally-actuated microfluidic valve is presented.The valve itself is fabricated with off-the-shelf components without the need for sophisticated cleanroom techniques.It is shown that multiple valves can be controlled and operated via a power supply and an Arduino microcontroller;an important step towards transportable microfluidic devices capable of carrying out analytical assays at the point-of-care.It is been calculated that a single actuator costs less than$1,this highlights the potential of the presented valve for scaling out.The valve operation is demonstrated by adjusting the ratio of a water/dye mixture in a continuous flow microfluidic chip with Y-junction channel geometry.The power required to operate one microfluidic valve has been characterised both theoretically and experimentally.Cyclical operation of the valve has been demonstrated for 65 h with 585 actuations.The presented valve is capable of actuating rectangular microfluidic channels of 500μm×50μm with an expected temperature increase of up to 5°C.The fastest actuation times achieved were 2 s for valve closing(heating)and 9 s for valve opening(cooling).