  Non-destructive testing and medical diagnostic techniques using ultrasound
has become indispensable in evaluating the state of materials or imaging the
internal human body, respectively. To conduct spatially resolved high-quality
observations, conventionally, sophisticated phased arrays are used both at the
emitting and receiving ends of the setup. In comparison, single-sensor imaging
techniques offer significant benefits including compact physical dimensions and
reduced manufacturing expenses. However, recent advances such as compressive
sensing have shown that this improvement comes at the cost of additional
time-consuming dynamic spatial scanning or multi-mode mask switching, which
severely hinders the quest for real-time imaging. Consequently, real-time
single-sensor imaging, at low cost and simple design, still represents a
demanding and largely unresolved challenge till this day. Here, we bestow on
ultrasonic metasurface with both disorder and artificial intelligence (AI). The
former ensures strong dispersion and highly complex scattering to encode the
spatial information into frequency spectra at an arbitrary location, while the
latter is used to decode instantaneously the amplitude and spectral component
of the sample under investigation. Thus, thanks to this symbiosis, we
demonstrate that a single fixed sensor suffices to recognize complex ultrasonic
objects through the random scattered field from an unpretentious metasurface,
which enables real-time and low-cost imaging, easily extendable to 3D.
