"We can detect tiny motion more locally and precisely with these plasmonic resonators than any other way of doing it," said NIST physicist Vladimir Aksyuk.
Applications include sensing trace amounts of hazardous biological or chemical agents; perfecting the movement of miniature robots; accurately deploying airbags; and detecting weak sound waves travelling through thin films.
According to Aksyuk, interaction between the device’s laser light and the plasmons is critical for sensing tiny displacements from nanoscale particles.
With the right choice of wavelength, the laser light causes plasmons of a particular frequency to resonate along a small air gap.
Meanwhile, as the nanoparticle moves, it changes the width of the gap and the frequency at which the plasmons resonate.
Light can't easily detect the location or motion of an object smaller than the wavelength of the laser, but converting the light to plasmons overcomes this limitation. Because the plasmons are confined to a gap, they are more sensitive than light for sensing the motion of small objects.
The amount of reflected laser light reveals the width of the gap and the motion of the nanoparticle.
