The invention of the embodiment discloses an implantable medical device. The implantable medical device includes chemical sensors with biodegradable mask layers for conducting hierarchical activationon the sensors. In the embodiment, the implantable medical device includes a substrate defining a plurality of traps, the first chemical sensors and the second chemical sensors, wherein the first andsecond chemical sensors are distributed in the separate traps of the substrate. The first chemical sensors and the second chemical sensors can be used for detecting one or more analyzed objects. The device can comprise the first biodegradable mask layers, wherein the first biodegradable mask layers are distributed above the second chemical sensors to seal the second chemical sensors. The device can further include protective flattening layers, wherein the protective flattening layers are distributed above at least one of the first chemical sensors and the second chemical sensors, so that the outermost layer surfaces of the upper portions of the first chemical sensors are flush with the outermost layer surfaces of the upper portions of the second chemical sensors in the medical device. Theinvention also involves other embodiments.