A team of researchers from the University of Florida, led by Dr. Philip Feng, in collaboration with Prof. Steven Shaw in Florida Institute of Technology, has now demonstrated extremely high-efficient mechanical signal amplification in nanoscale mechanical resonators operating at radio frequency. The devices employed in this research might be the tiniest mechanical resonators exhibiting amplification, and the gain achieved is the highest known for all mechanical devices reported to date.
The displacement amplification is realized based on “parametric pumping or parametric amplification” of mechanical motion. Parametric amplification can be mainly achieved when a parameter of system is modulated by twice multiples of the frequency. A simple example of parametric amplification is a child playing a swing. The child can periodically stand and squat twice in a single period of the swing to increase or “amplify” the swing amplitude without anyone helping to push.
The researchers have realized the parametric amplification in the tiny nanoscale devices. The nanoscale drumhead mechanical parametric amplifiers demonstrated in this research consist of an atomically thin two-dimensional semiconducting molybdenum disulfide (MoS2) membrane where the thickness of the drumheads is 0.7, 2.8, 7.7 nanometer with 1.8 micrometer in diameter and 0.0018–0.020 m3 in volume. The nanodrums are fabricated by transferring nanosheet exfoliated from bulk crystal over microcavities to make suspended atomically thin nanodrums.
