This paper presents a miniature, imperceptible, and biocompatible smart contact lens (SCL) designed for in-situ eye tracking and wireless eye-machine interaction. The SCL employs frequency encoding to detect eye movements and closures, achieving an angular accuracy of <0.5°, which is even better than the central fovea's vision range. It supports multiple applications, including eye-drawing, games, web interaction, camera control, and robot vehicle control. Comprehensive biocompatibility tests, including cytotoxicity and eye irritation assessments, demonstrate low cytotoxicity and minimal eye irritation. The SCL is expected to enhance eye tracking techniques and promote the development of human-machine interaction technology. The paper also includes detailed design, characterization, and experimental results, showcasing the SCL's performance in various tests and its potential for practical applications.This paper presents a miniature, imperceptible, and biocompatible smart contact lens (SCL) designed for in-situ eye tracking and wireless eye-machine interaction. The SCL employs frequency encoding to detect eye movements and closures, achieving an angular accuracy of <0.5°, which is even better than the central fovea's vision range. It supports multiple applications, including eye-drawing, games, web interaction, camera control, and robot vehicle control. Comprehensive biocompatibility tests, including cytotoxicity and eye irritation assessments, demonstrate low cytotoxicity and minimal eye irritation. The SCL is expected to enhance eye tracking techniques and promote the development of human-machine interaction technology. The paper also includes detailed design, characterization, and experimental results, showcasing the SCL's performance in various tests and its potential for practical applications.