  Object localization through active elastic waves is a crucial technology, but
generally requires a transducer array with complex hardware. Although
computational sensing has been demonstrated to be able to overcome the
short-comings of transducer array by merging artificially designed structures
into sensing process, coding spatial elastic waves for active object
identification is still a knowledge gap. Here we propose a scattering-coded
elastic meta-boundary composed of randomly distributed scatterers for
computational identification of objects with a single transducer. The multiple
scattering effect of the meta-boundary introduces complexity into scattered
fields to achieve a highly uncorrelated scattering coding of elastic waves,
thereby eliminating the ambiguity of the object location information. We
demonstrate that the locations of objects can be uniquely identified by using
the scattering coding of our designed meta-boundary, delivering a design of
meta-boundary touchscreen for human-machine interaction. The proposed
scattering-coded meta-boundary opens up avenues for artificially designed
boundaries with the capability of information coding and identification, and
may provide important applications in wave sensing, such as structural
monitoring, underwater detection, indoor localization, and biomedical imaging.
