A system comprising an electronic device (1, 2, 3, 4, 5) and an energy harvesting module, the electronic device comprising: a first housing; a second housing; a support configured to couple the first housing and the second housing such that the first housing is rotatable with respect to the second housing; a spring configured to apply an elastic force to the first housing and the second housing such that one end of the first housing abuts against one end of the second housing; a connector disposed within the first housing; a secondary battery configured to store therein power that is supplied from the energy harvesting module via a connector of the energy harvesting module; and a load circuit element capable of consuming power supplied from the energy harvesting module or power supplied from the secondary battery, wherein the secondary battery and the load circuit element are disposed within either of the first housing and the second housing, wherein the first housing, the second housing, the support and the spring function as a clip capable of clamping an object between the one end of the first housing and the one end of the second housing, and wherein the connector is mechanically and electrically attachable to or detachable from the connector of the external energy harvesting module through an opening provided in a side surface of the first housing, and characterized in that a whole of the external energy harvesting module is detachable, and the connector of the energy harvesting module is connected with the connector of the electronic device (1, 2, 3, 4, 5) by inserting the connector of the energy harvesting module into the opening. a first housing; a second housing; a support configured to couple the first housing and the second housing such that the first housing is rotatable with respect to the second housing; a spring configured to apply an elastic force to the first housing and the second housing such that one end of the first housing abuts against one end of the second housing; a connector disposed within the first housing; a secondary battery configured to store therein power that is supplied from the energy harvesting module via a connector of the energy harvesting module; and a load circuit element capable of consuming power supplied from the energy harvesting module or power supplied from the secondary battery, wherein the secondary battery and the load circuit element are disposed within either of the first housing and the second housing, wherein the first housing, the second housing, the support and the spring function as a clip capable of clamping an object between the one end of the first housing and the one end of the second housing, and wherein the connector is mechanically and electrically attachable to or detachable from the connector of the external energy harvesting module through an opening provided in a side surface of the first housing, and characterized in that a whole of the external energy harvesting module is detachable, and the connector of the energy harvesting module is connected with the connector of the electronic device (1, 2, 3, 4, 5) by inserting the connector of the energy harvesting module into the opening.