Abstract: Implementations of data logger systems may include: a data logger coupled with an energy storage device. The data logger may be configured to couple to a living subject and record data related to one of the living subject's activities and a vital parameter of the living subject. The data logger system may also include an energy harvester electrically coupled with the energy storage device, where the energy harvester is configured to harvest energy from one of an external environment, the living subject, and both the external environment and the subject. The data logger may be configured to communicate with a remote communication system.