Plasmonics Promises Better Biosensors

But the near-term goal, bloodless blood-glucose monitoring, is likely out of reach

4 min read

7 March 2012—Drawing blood is a daily reality for most people with diabetes. And while checking glucose levels probably isn’t the worst part of the disease, it’s such a pervasive nuisance that someone from nearly every scientific discipline has tried to invent a better way to do it. They’ve pasted transdermal patches to the skin and shone near-infrared light through the earlobes, but still nothing can beat the accuracy of a little drop of blood. 

Evidently, the quest for a better way is not over. Last month, engineers came up with new artillery—a plasmonic interferometer that can detect very low concentrations of glucose in water and, with some reengineering, may also work with saliva. If things go as hoped, people with diabetes will one day measure glucose levels by spitting instead of sticking.

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Restoring Hearing With Beams of Light

Gene therapy and optoelectronics could radically upgrade hearing for millions of people

13 min read
A computer graphic shows a gray structure that’s curled like a snail’s shell. A big purple line runs through it. Many clusters of smaller red lines are scattered throughout the curled structure.

Human hearing depends on the cochlea, a snail-shaped structure in the inner ear. A new kind of cochlear implant for people with disabling hearing loss would use beams of light to stimulate the cochlear nerve.

Lakshay Khurana and Daniel Keppeler

There’s a popular misconception that cochlear implants restore natural hearing. In fact, these marvels of engineering give people a new kind of “electric hearing” that they must learn how to use.

Natural hearing results from vibrations hitting tiny structures called hair cells within the cochlea in the inner ear. A cochlear implant bypasses the damaged or dysfunctional parts of the ear and uses electrodes to directly stimulate the cochlear nerve, which sends signals to the brain. When my hearing-impaired patients have their cochlear implants turned on for the first time, they often report that voices sound flat and robotic and that background noises blur together and drown out voices. Although users can have many sessions with technicians to “tune” and adjust their implants’ settings to make sounds more pleasant and helpful, there’s a limit to what can be achieved with today’s technology.

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