This paper aims to address the typical needs met in designing Bio/CMOS interfaces for the remote monitoring of human metabolism. In particular, the design of robust and reliable interfaces for wearable, implantable, or point-of-care devices is considered as model application. Selectivity, sensitivity, and autonomy of such devices are introduced and discussed as the main features of such personal tools for health monitoring. The typical solutions presented in literature to assure the right selectivity, sensitivity, and autonomy are discussed in detail. Some of those solutions are on board in many technologies introduced into the market already, demonstrating the feasibility of such design approach obtained by integrating three system' layers: bio, nano, and CMOS (Complementary Metal-Oxide-Semiconductor). These largely spread technologies for personal health monitoring (e.g., the glucose auto-monitoring devices for chronic patients with diabetes) provide distributed diagnostics in term of billions of connected devices. Billions of connected personal devices worldwide distributed oblige to consider the several issues related to sustainability in term of minimal environmental impact. Therefore, the paper also introduces some new emerging design strategies by modular design, substrates made of recycled plastic or bioplastics by crop waste, and biodegradable materials.