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Diagnosis in the Fast Lane

A simple device, plus saliva, can equal a test result in just eight minutes.

By Logan Ward // Fall 2008

With two microscope slides, one computer chip and nine volts of electricity, a new saliva analyzer can return results in eight minutes, as opposed to several hours. Here’s how it works.

Minutes 0 to 2: A negative electrode is attached to the antibody well (full of fluorescent antibodies to protein biomarkers present in the disease being tested for), and a positive one to the sample waste well. When a current is applied, the antibodies are drawn by the positive charge into a membrane, where they lodge, too large to pass through.

Minutes 2 to 4: Voltage drives the saliva to the membrane, where any proteins get stuck alongside the antibodies. If any of the proteins are biomarkers, they will bind to the antibodies.

Minutes 4 to 5: Voltage is applied to drive buffer fluid to the sample waste well, flushing out any remaining saliva.

Minutes 5 to 8: Voltage drives the antibodies and proteins up a long channel, which contains sieving gel. Each molecule, when subjected to a charge, travels a certain distance through the gel based on its mass. Because these distances are quantifiable, the device can recognize which proteins are bound to antibodies. The device then measures the ratio of bound proteins (signifying the presence of the disease) to unbound (healthy) proteins.


Studies in Miniature


Liquids act differently in tiny spaces, enabling lab-on-a-chip technology to transform research, drug discovery and disease diagnosis.

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