Passive Directional Valve Technology: Towards More User-friendly and Accessible Microfluidic Devices for Diagnostic and Research Applications

The Problem

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Automated fluid-transporting and processing systems that function on the scale of micrometers (microfluidic systems) are becoming increasingly important for advancing various diagnostic, drug fabrication and delivery, and tissue engineering applications. Efforts to create smaller microfluidic devices with functionalities realized at larger scales rely heavily on valves to enable the regulated transport of samples and fluids, fluid mixing, incubation, processing, and analysis. The prevailing valve designs are largely mechanical and require external connections to power or pressure sources, which complicates the overall architecture of devices and stands in the way of using multiple valves in the same device, and miniaturizing and commercializing robustly functioning devices. In addition, current efforts to engineer chain reactions in microfluidic devices are met with the challenge that the materials require precise surface treatments and are incompatible with reagents and samples commonly used in many diagnostic or research-related assays, like oily substances, alcohols, and organic acids, bases and solvents.

Our Solution

We have addressed these challenges by pioneering a novel passive directional valve technology, which enables the design and fabrication of microfluidic devices capable of handling real-world samples and reagents within multiple applications. Passive directional valves facilitate complex microfluidic operations without the need for external peripherals or power sources by leveraging controllable channels that are integrated with uniquely designed stop valves, and enable programmed fluid movements. Passive directional valves are fabricated with patterned layers of hydrophilic and hydrophobic films enabling spatial “wettability” in different sections of the valve, as well as geometries that dictate pressure differentials across the length of the valves. Their fabrication is compatible with common polymer substrates and eliminates the need for additional surface treatments, thereby allowing an easy scale up of microfluidic device manufacturing.

Passive directional valves have enormous potential to advance a broad spectrum of chemical and biological assays, including assays based on DNA extraction and amplification, CRISPR-based diagnostics, as well as multiplexed ultra-sensitive diagnostic sensing. Passive directional valves could also enable transistor-like logic AND, OR, and NOT operations on microfluidic chips in the future to unlock true research and clinical “lab-on-chip” applications.

Product Journey

The passive directional valve technology was developed by present and former members of the Wyss Institute’s Advanced Technology Team, including Mohammed Yafia, Pawan Jolly, and Adama Sesay, who worked with Wyss Founding Director Donald Ingber on this new microfluidic approach. Originally conceived as an enhancement for human Organ Chips in Ingber’s lab to enable next-level microfluidic operations and analysis in engineered microtissues, the valves have since become promising components for multiple other applications with research and diagnostic potential, including point-of-care diagnostic testing.

In a 2022 study, the team collaborated with Wyss Core Faculty member James Collins to provide proof-of-concept for their invention in a multi-functional COVID-19 diagnostic device. By engineering a 3D-printed lab-on-a-chip device using their passive valve technology in combination with advanced nucleic acid and protein detection technologies and other features, they were able to simultaneously detect RNA and different proteins of the SARS-CoV-2 virus. The device automatedly extracted, amplified, and CRISPR-analyzed RNA and detected multiple viral proteins with inexpensive electrochemical sensors, thus becoming a prototype for future point-of-care diagnostic applications with multiplexed detection capabilities, with simplicity comparable to lateral flow devices used, for example, in COVID-19 and pregnancy tests.