  This article discusses the employment of simultaneously transmitting and
reflecting surface (STARS) for integrated sensing and communication (ISAC)
networks. First, two fundamental configurations of STARS-enabled ISAC systems
are introduced, namely integrated full-space configuration and separated
half-space configuration, as well as their respective advantages and common
challenges are identified. To address the aforementioned challenges, a novel
sensing-at-STARS design is proposed, where the sensing functionality is
achieved at the STARS instead of at the base station. Such a design
significantly improves the echo signal energy by eliminating undesired echo
energy attenuation/leakage, in addition to establishing favorable echo
propagation paths to facilitate sensing information extraction. We also present
three practical implementations for sensing-at-STARS, including separated
elements, mode-selection elements, and power-splitting elements. Each
implementation enables flexible sensing-communication tradeoffs. Numerical
results are provided to demonstrate the superiority of the proposed
STARS-enabled ISAC design. Finally, we discuss several future research
directions.
