  We study the bi-laplacian Schr\"odinger equation with a general interaction
term, which can be either linear or nonlinear, and is time-dependent. We prove
that the global solutions for this equation are asymptotically given by a free
wave and a weakly localized part. The proof relies on constructing the Free
Channel Wave Operator in a new way, based on the method developed from recent
studies \cite{SW20221}.
