A simple and reliable microfabrication process for a programmable microvalve array

A programmable microfluidic platform to monitor calcium dynamics in microglia during inflammation

Neuroinflammation is characterized by the elevation of cytokines and adenosine triphosphate (ATP), which in turn activates microglia. These immunoregulatory molecules typically form gradients in vivo, which significantly influence microglial behaviors such as increasing calcium signaling, migration, phagocytosis, and cytokine secretion. Quantifying microglial calcium signaling in the context of inflammation holds the potential for developing precise therapeutic strategies for neurological diseases. However, the current calcium imaging systems are technically challenging to operate, necessitate large volumes of expensive reagents and cells, and model immunoregulatory molecules as uniform concentrations, failing to accurately replicate the in vivo microenvironment. In this study, we introduce a novel calcium monitoring micro-total analysis system (CAM-μTAS) designed to quantify calcium dynamics in microglia (BV2 cells) within defined cytokine gradients. Leveraging programmable pneumatically actuated lifting gate microvalve arrays and a Quake valve, CAM-μTAS delivers cytokine gradients to microglia, mimicking neuroinflammation. Our device automates sample handling and cell culture, enabling rapid media changes in just 1.5 s, thus streamlining the experimental workflow. By analyzing BV2 calcium transient latency to peak, we demonstrate location-dependent microglial activation patterns based on cytokine and ATP gradients, offering insights contrasting those of non-gradient-based perfusion systems. By harnessing advancements in microsystem technology to quantify calcium dynamics, we can construct simplified human models of neurological disorders, unravel the intricate mechanisms of cell-cell signaling, and conduct robust evaluations of novel therapeutics.

Integrated high performance microfluidic organic analysis instrument for planetary and space exploration

The exploration of our solar system to characterize the molecular organic inventory will enable the identification of potentially habitable regions and initiate the search for biosignatures of extraterrestrial life. However, it is challenging to perform the required high-resolution, high-sensitivity chemical analyses in space and in planetary environments. To address this challenge, we have developed a microfluidic organic analyzer (MOA) instrument that consists of a multilayer programmable microfluidic analyzer (PMA) for fluidic processing at the microliter scale coupled with a microfabricated glass capillary electrophoresis (CE) wafer for separation and analysis of the sample components. Organic analytes are labeled with a functional group-specific (e.g. amine, organic acid, aldehyde) fluorescent dye, separated according to charge and hydrodynamic size by capillary electrophoresis (CE), and detected with picomolar limit of detection (LOD) using laser-induced fluorescence (LIF). Our goal is a sensitive automated instrument and autonomous process that enables sample-in to data-out performance in a flight capable format. We present here the design, fabrication, and operation of a technology development unit (TDU) that meets these design goals with a core mass of 3 kg and a volume of <5 L. MOA has a demonstrated resolution of 2 × 105 theoretical plates for relevant amino acids using a 15 cm long CE channel and 467 V cm-1. The LOD of LIF surpasses 100 pM (0.01 ppb), enabling biosignature detection in harsh environments on Earth. MOA is ideally suited for probing biosignatures in potentially habitable destinations on icy moons such as Europa and Enceladus, and on Mars.

A Programmable Microfluidic Platform to Monitor Calcium Dynamics in Microglia during Inflammation

Calcium dynamics significantly influence microglial cell immune responses, regulating activation, migration, phagocytosis, and cytokine release. Understanding microglial calcium signaling is vital for insights into central nervous system immune responses and their impact on neuroinflammation. We introduce a calcium monitoring micro-total analysis system (CAM-μTAS) for quantifying calcium dynamics in microglia (BV2 cells) within defined cytokine microenvironments. The CAM-μTAS leverages the high efficiency pumping capabilities of programmable pneumatically actuated lifting gate microvalve arrays and the flow blocking capabilities of the Quake valve to deliver a cytokine treatment to microglia through a concentration gradient, therefore, biomimicking microglia response to neuroinflammation. Lifting gate microvalves precisely transfer a calcium indicator and culture medium to microglia cells, while the Quake valve controls the cytokine gradient. In addition, a method is presented for the fabrication of the device to incorporate the two valve systems. By automating the sample handling and cell culture using the lifting gate valves, we could perform media changes in 1.5 seconds. BV2 calcium transient latency to peak reveals location-dependent microglia activation based on cytokine and ATP gradients, contrasting non-gradient-based widely used perfusion systems. This device streamlines cell culture and quantitative calcium analysis, addressing limitations of existing perfusion systems in terms of sample size, setup time, and biomimicry. By harnessing advancements in microsystem technology to quantify calcium dynamics, we can construct simplified human models of neurological disorders, unravel the intricate mechanisms of cell-cell signaling, and conduct robust evaluations of novel therapeutics.

Operation of a programmable microfluidic organic analyzer under microgravity conditions simulating space flight environments

A programmable microfluidic organic analyzer was developed for detecting life signatures beyond Earth and clinical monitoring of astronaut health. Extensive environmental tests, including various gravitational environments, are required to confirm the functionality of this analyzer and advance its overall Technology Readiness Level. This work examines how the programmable microfluidic analyzer performed under simulated Lunar, Martian, zero, and hypergravity conditions during a parabolic flight. We confirmed that the functionality of the programmable microfluidic analyzer was minimally affected by the significant changes in the gravitational field, thus paving the way for its use in a variety of space mission opportunities.