Magnetic-adhesive based valves for microfluidic devices used in low-resource settings

Abstract

Since the introduction of micro total analytical systems (μTASs), significant advances have been made toward development of lab-on-a-chip platforms capable of performing complex biological assays that can revolutionize public health, among other applications. However, use of these platforms in low-resource environments (e.g. developing countries) has yet to be realized as the majority of technologies used to control microfluidic flow rely on off-device hardware with non-negligible size, cost, power requirements and skill/training to operate. In this paper we describe a magnetic-adhesive based valve that is simple to construct and operate, and can be used to control fluid flow and store reagents within a microfluidic device. The design consists of a port connecting two chambers on different planes in the device that is closed by a neodymium disk magnet seated on a thin ring of adhesive. Bringing an external magnet into contact with the outer surface of the device unseats and displaces the valve magnet from the adhesive ring, exposing the port. Using this configuration, we demonstrate on-device reagent storage and on-demand transport and reaction of contents between chambers. This design requires no power or external instrumentation to operate, is extremely low cost ($0.20 materials cost per valve), can be used by individuals with no technical training, and requires only a hand-held magnet to actuate. Additionally, valve actuation does not compromise the integrity of the completely sealed microfluidic device, increasing safety for the operator when toxic or harmful substances are contained within. This valve concept has the potential to simplify design of μTASs, facilitating development of lab-on-a-chip systems that may be practical for use in point-of-care and low-resource settings.

Microfluidic Passive Valve with Ultra-Low Threshold Pressure for High-Throughput Liquid Delivery

“…Other materials, such as thermal plastic polymer [11,12], shape memory alloy [13,14], glass [15], and more are also used in certain situations. As for the deflection of the membrane, various mechanical [16,17], electrostatic [18,19], pneumatic [20,21], magnetic [22,23], piezoelectric [24], or thermal [25] mechanisms have been proposed. Among the actuation mechanisms, pneumatic actuation is apparently the most commonly used technology.…”

Microfluidic Passive Flow Regulatory Device with an Integrated Check Valve for Enhanced Flow Control

“…According to the working principle of a microfluidic valve, the reported valves can be classified as active type and passive type [9]. Active valves usually use external actuators such as pressurized gas [10,11,12], magnetic [13,14], electric [15,16], or thermal forces [17] to adjust the flow resistances of microchannels. As many actuators are highly sensitive, liquid can be controlled consciously and precisely, which enables the high compatibility of active valves in microfluidic large-scale integration [18,19,20].…”

Point-of-Care Diagnostics: Recent Developments in a Connected Age

“…Optically-driven photodeformable polymers could be manipulated to exert control over a variety of fluids 223 , which could represent a new tool in microfluidic design 223 , although feasibility of actuating one component without affecting others in a high density chip would still need to be demonstrated. Valves based on magnetic adhesives have been developed for mixing reagents, requiring no power 224 . A wax-based valve that was thermally actuated and could be used repeatedly was demonstrated on lateral flow assays to increase flexibility and complexity 225 .…”