Bioanalysis Zone

Modular valve for microfluidic chips allows on the spot diagnosis of disease

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Researchers have swapped delicate microscopic flow valves for a universal modular valve system allowing a significant decrease in the cost and complexity of microfluidic diagnostic chips. The team have developed devices the size of business card that allow on the spot detection of a range of disease biomarkers in blood.

“Microfluidic chips are advancing point-of-care diagnosis for many diseases,” explained Alicia Toh from A*STAR’s Singapore Institute of Manufacturing Technology (SIMTech). “Inside these chips, tiny microvalves precisely direct microlitres of fluid through a series of microchannels for automated analysis.”

“However, integrating microvalves into the microchannels is complex and highly susceptible to fabrication defects, which translates into a higher cost per device. In the medical diagnostic sector the race is on to lower the cost per diagnosis by producing cheaper microfluidic diagnostic chips.”

Toh and her colleagues Zhiping Wang and Zhenfeng Wang moved the microvalves off the main microfluidic chip and, after fabrication, fitted a modular valve to the surface of the chip.

The valves are made up of a microfluidic channel connecting to surface ports on the chip as well as an air chamber that allows the channel to be pinched by increasing the air pressure. It was demonstrated by the team using fluidic routing that their modular valves could precisely manipulate chemical concentrations – a crucial facet of advanced diagnostic applications.

“By mass producing these microvalve modules separate from the microfluidic chip and testing valve function prior to chip integration, we can achieve much lower defect rates, which boosts yields and results in a much lower cost per device,” says Toh. “This technology will reduce waste and help contribute to sustainable manufacturing practices for microfluidic chips.”

The process of designing the valve was, however, complicated. State-of-the-art software was used by the team to allow prediction of interaction between the fluid in the microchannel and the flexible elastomeric silicone membrane.

Constraints were also placed on development of the device because of the need to use materials that are compatible with the latest microfluidics technologies.

“The industry is rapidly moving toward more cost effective thermoplastic materials,” says Toh. “By using compatible materials, we can achieve reliable integration without additional surface modification or adhesives.”

A variety of novel materials are now being explored by the team which can be used in the production of microvalve modules. “Greater adoption of microfluidic technology will mean that we could see our modular microvalves being used in a wide spectrum of applications,” she added.

Source: Toh AG, Wang Z, Wang Z. Modular membrane valves for universal integration within thermoplastic devices. Microfluid Nanofluid 20(6), (2016).

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