The American Heart Association has given high blood pressure the nickname “silent killer” for very good reasons. However, all of that could change with new implantable, biocompatible nanowires being developed at the Georgia Institute of Technology.
Nanowires that produce a current during bending could one day be implanted into the body to monitor changes in blood pressure, researchers claim.
Zhong Lin Wang and colleagues at the Georgia Institute of Technology in Atlanta, US, took advantage of the piezoelectric effect in semiconducting zinc oxide nanowires to create a new class of components. They can detect forces as small as a few piconewtons (10-12 N), roughly the force required to “unzip” a strand of DNA.
Zinc oxide nanowires show a powerful piezoelectric effect – that is, they produce a current when they are bent. Normally, the positive and negative charges of zinc and oxygen ions in the crystalline nanowires cancel each other out.
However, when the wires – which Wang’s team built to stand vertically on top of an electrode – are bent, this displaces the ions. This unbalances the charges, creating an electric field that produces an electric potential across the nanowire, which affects the current flowing through it.
Zinc oxide is “biocompatible”, so the nanowire sensors could be implanted in an arm, says Wang. Once in place, tiny changes in pressure from pulsing blood vessels would bend them, creating a current and allowing blood pressure to be continuously measured. The sensor could then wirelessly transmit the pressure reading to an external receiver device, perhaps worn on the wrist, which would then display the data.
The researchers add that such a pressure sensor could even be self-powered in the future by combining it with a “nanogenerator” (pictured above), which the Georgia Tech group made last year. The nanogenerator uses the piezoelectric effect to generate power as the patient moves and this would power the pressure sensor without the need for batteries.
“This is really great work,” Yi Ciu of Stanford University told New Scientist. “The wires have high sensitivity because they are very small, so tiny pressures can be measured.”
New Scientist Tech . . .
Abstract . . .
Georgia Institute of Technology press rellease: New Electronic Devices Created from Bent Nanowires. . .
(hat tip: Engadget)