McGill University scientists have developed a way to place electric charges onto quantum dots (particles sized <10 nm). This in turn created a strong electric field within the dots leading to a very fast piezoelectric effect that contracted and expanded the dots. This is apparently the first case of a piezoelectric effect controlled at the nanoscale, which should help miniaturize many existing sensors and therapeutic devices and lead to new ones that work on smaller scale biological processes.
Cadmium Selenide quantum dots can be used in a wide range of technological applications. Solar power is one area that has been explored, but this new discovery has paved way for other nanoscale device applications for these dots. This discovery offers a way of controlling the speed and switching time of nanoelectronic devices, and possibly even developing nanoscale power supplies, whereby a small compression would produce a large voltage.
"The piezoelectric effect has never been manipulated at this scale before, so the range of possible applications is very exciting," explained Pooja Tyagi, a PhD researcher in Professor Patanjali Kambhampati’s laboratory. "For example, the vibrations of a material can be analyzed to calculate the pressure of the solvent they are in. With further development and research, maybe we could measure blood pressure non-invasively by injecting the dots, shining a laser on them, and analyzing their vibration to determine the pressure." Tyagi notes that Cadium Selenide is a toxic metal, and so one of the hurdles to overcome with regard to this particular example would be finding a replacement material.
More from McGill: Good Vibrations: new atom-scale products on horizon…
Abstract in NANO Letters: Controlling Piezoelectric Response in Semiconductor Quantum Dots via Impulsive Charge Localization