Advancements in the field of wearable and implantable technologies have the potential to improve significantly the healthcare monitoring and the therapy efficiency, while reducing medical costs. To achieve a continuous, unobtrusive and local monitoring of physiological parameters, it is essential the development of highly miniaturized and energy efficient devices equipped with sensing, computing and wireless communication capabilities. Recent research effort has raised the prospect of moving beyond the well-established concept of implantable and wearable systems, through the conceptualization of the "Smart Dust". The tight resource-constraints of such systems generate many challenges, which can be addressed through new design approaches and optimization strategies, especially concerning size and power consumption.