  Nanoelectromechanical systems (NEMS) have proven outstanding performance in
the detection of small masses down to single proton sensitivity. To obtain a
high enough throughput for the application in practical mass spectrometry, NEMS
resonators have to be arranged in two-dimensional (2D) arrays. However, all
state-of-the-art electromechanical transduction methods rely on electrical
lines placed close to the mechanical resonators, which drastically restricts
the density of 2D resonator arrays. An exception is the transduction by surface
acoustic waves (SAWs), which has so far only been shown for the transduction of
single nanomechanical pillar resonators. Here, we demonstrate the transduction
of pillar pairs by surface acoustic waves. The pillars have a diameter of 700
nm and show a mass responsivity of -588$\pm$98 ng$^{-1}$. The distances between
the pillar pairs are 70 nm and 14.3 $\mu$m. SAW transduction enabled us to
measure both pillars of each pair with electrical lines no closer than 300
$\mu$m, illustrating the potential of SAWs to transduce dense arrays of pillar
resonators, a crucial step towards practical mass spectrometry with NEMS.
