  Nonlocal deformation sensing achieved by integrating atomic force microscopy
indentation with nanodiamond-based orientation tracking features high precision
and high spatial resolution, providing a useful technique for studying the
mechanical properties of soft biological systems. However, this technique is
currently limited to lifeless systems because it cannot differentiate the
indentation-induced deformation from that associated with live activities or
other external perturbations. Here we develop a dynamic nonlocal deformation
sensing method using oscillatory nanoindentation and spectroscopic analysis to
overcome this limitation. The method realizes both temporally and spatially
resolved mechanical analysis, with tens of microsecond time-lag precision,
nanometer vertical deformation precision, and sub-hundred nanometer lateral
spatial resolution, leading to the disclosure of surface/interface effects in
the mechanical response of viscoelastic materials and live cells. Neglecting
surface tension would underestimate the liquid-like characteristics of the
materials. This work demonstrates nanodiamond sensors as a useful tool for
spatial-temporal mechanical analysis of soft, complex bio-relevant materials.
