Flexure-FET Biosensor Promises High Sensitivity for Medical Diagnostics

Researchers from Purdue University are reporting in the Proceedings of the National Academy of Sciences the development of a novel new biosensor that combines mechanical and electrical components that together make the device more sensitive than either alone.

The device, known as Flexure-FET biosensor, measures a sample’s mass, size, and electrical charge. If the sample is not charged, the mechanical measurements are still effective, making the sensor applicable in a variety of situations. The device is able to detect DNA fragments and proteins in a sample, making it potentially a highly useful tool in detecting cancer and generally for the growing field of personalized medicine.

Some details of how it functions, from a Purdue announcement:

In early cancer diagnostics, the sensor makes possible the detection of small quantities of DNA fragments and proteins deformed by cancer long before the disease is visible through imaging or other methods, Alam [Muhammad A. Alam, a Purdue University professor of electrical and computer engineering] said.

The sensor’s mechanical part is a vibrating cantilever, a sliver of silicon that resembles a tiny diving board. Located under the cantilever is a transistor, which is the sensor’s electrical part.

In other mechanical biosensors, a laser measures the vibrating frequency or deflection of the cantilever, which changes depending on what type of biomolecule lands on the cantilever. Instead of using a laser, the new sensor uses the transistor to measure the vibration or deflection.

The sensor maximizes sensitivity by putting both the cantilever and transistor in a “bias.” The cantilever is biased using an electric field to pull it downward as though with an invisible string.

“This pre-bending increases the sensitivity significantly,” Jain said.

The transistor is biased by applying a voltage, maximizing its performance as well.

“You can make the device sensitive to almost any molecule as long as you configure the sensor properly,” Alam said.

A key innovation is the elimination of a component called a “reference electrode,” which is required for conventional electrical biosensors but cannot be miniaturized, limiting practical applications.

Link @ Purdue: Ultrasensitive biosensor promising for medical diagnostics…