NOVELTY - A power source device for sensor nodes (400) of a ubiquitous sensor network (USN) comprises a dye-sensitized solar cell (100) having a self-powering function; a secondary battery (200) storing electricity generated by the solar cell and supplying the electricity to the sensor nodes of the USN; and an interface circuit (300) interfacing the solar cell with the secondary battery, where the solar cell, the secondary battery, and the interface circuit are mounted on the sensor nodes.    USE - As a power source device for sensor nodes of a ubiquitous sensor network (claimed).    ADVANTAGE - The power source device supplies stable power, is relatively inexpensive, and small enough to be installed in the sensor nodes of the USN. The power source device can supply power for at least 10 years and has a width of less than or equal to 30 mmx30 mm and a thickness of less than or equal to 3 mm, i.e. the device is compact so as to be mounted on the sensor nodes. The power source device can continuously store electricity generated from the self-powered dye-sensitized solar cell in the lithium secondary battery and continuously and stably supply a low current necessary for the sensor nodes forming a network. The subminiature power source device can be mounted on the sensor nodes to maintain a power source system of sensor nodes within a network area over a long period of time scattered one time.    DETAILED DESCRIPTION - A power source device for sensor nodes (400) of a ubiquitous sensor network (USN) comprises a dye-sensitized solar cell (100) having a self-powering function; a secondary battery (200) storing electricity generated by the solar cell and supplying the electricity to the sensor nodes of the USN; and an interface circuit (300) interfacing the solar cell with the secondary battery, where the solar cell, the secondary battery, and the interface circuit are mounted on the sensor nodes.    DESCRIPTION OF DRAWING(S) - The figure shows a block diagram of a power source device for sensor nodes of a USN.    solar cell (100)    secondary battery (200)    interface circuit (300)    sensor node. (400)