The torsion balance contains a rigid balance beam
suspended by a fine thread as an ancient scientific instrument that
continues to form a very sensitive force sensor to date. The force
sensitivity is proportional to the lengths of the beam and thread
and inversely proportional to the fourth power of the diameter of
the thread; therefore, nanomaterials that support the torsion
balances should be ideal building blocks. In a new report now
published on Science Advances, Lin Cong and a research team in
quantum physics, microelectronics and nanomaterials in China have
detailed a torsional balance array on a chip with the highest
sensitivity level. The team facilitated this by using a carbon
nanotube as the thread and a monolayer graphene coated with
aluminum films as the beam and mirror. Using the experimental
setup, Cong et al. measured the femtonewton force exerted by a weak
laser. The balances on the chip served as an ideal platform to
investigate fundamental interactions up to zeptonewton in
accuracy.
On-chip torsion balance with femtonewton force resolution at
room temperature
