Microfluidic device uses tiny beads to detect sepsis within minutes

Measuring several square centimeters in size, the current version of the device incorporates eight microfluidic channels, for measuring multiple biomarkers or blood samples in parallel(Credit: Felice Frankel)

Sepsis occurs when the body’s immune system releases chemicals to fight an infection, triggering widespread inflammation. If not treated soon enough, organ failure and even death can ultimately result. A new device, however, could detect it earlier than ever.

When someone is developing sepsis, levels of an inflammation-associated protein known as interleukin-6 (IL-6) may rise hours before any other symptoms appear. That said, traditional blood assays are still incapable of quickly detecting such an increase.

With that in mind, MIT scientists have developed a compact experimental diagnostic device – working with less than a finger-prick of blood, it spots “clinically significant” IL-6 concentrations within about 25 minutes. It does so utilizing loop-shaped microfluidic channels.

First off, in one of those channels, the blood is mixed with magnetic microbeads that are coated with an antibody which binds with IL-6. After about 10 minutes, all of the IL-6 protein present in the sample will have bound with some of the beads.

The blood/bead mixture is then pumped into another channel, where there’s an electrode that’s coated with another type of IL-6-binding antibody. After a further 10 minutes of circulating within that channel, onlythe beads containing IL-6 will have stuck to that electrode – the other beads get washed out of the channel.

When voltage is subsequently applied within the channel via the electrode, one electrical signal is produced by each bead. By counting those signals, a linked computer is able to determine the concentration of IL-6 within the sample.

As opposed to the 5 microliters of blood required by the device, a traditional blood assay machine needs 100 microliters to accurately detect IL-6 – it also takes hours to deliver a result, plus it’s bulky and expensive. And while other faster, more portable detectors have been developed, many of these are quite costly, as they incorporate fancy optical components.

The scientists are now working on adapting the MIT technology to detect concentrations of other biomarkers, associated either with sepsis or with other conditions.

“For an acute disease, such as sepsis, which progresses very rapidly and can be life-threatening, it’s helpful to have a system that rapidly measures these nonabundant biomarkers,” says PhD student and first author of the study, Dan Wu. “You can also frequently monitor the disease as it progresses.”


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