Clinical Engineering is the specialization of Bioengineering that focuses on the most practical aspect of biomedicine to improve the quality of health services. It is about theories and methodologies from the broad biomedical knowledge application.
It includes the appropriate management of life science technologies (purchasing, installation, revision, risk controlling), development, and adjustment of informative systems or telemedicine networks.
It includes therefore almost all the other fields, from human physiology and biomechanics to robotics, electronics, computer science, and it intends to anchor them in a specific context. Clinical engineers are mostly needed in Hospitals, but they can also work for other entities. They do management and logistics.
It's an always growing field, as biomedical technology increases toward ever more complex systems.
This little schema below summarizes well the tasks of clinical engineers and how they closely work with other fields. As you may see, it's the person who keeps everything together. They play an essential role.
I think is a field very interesting as it gives you a complete overview of the real integration of biomedicine in a concrete environment, and thus allows you to do a multidisciplinary job. Furthermore, I think it is particularly important in developing countries to help the population to create an efficient and modern healthcare system.