The invention provides systems and methods for wearable and tissue-mounted electronics for monitoring exposure of a subject or object to electromagnetic radiation, particularly electromagnetic radiation in the visible, ultraviolet and infrared portions of the electromagnetic spectrum. In some embodiments, the devices are purely passive devices where absorption of incident electromagnetic radiation by the device provides at least a portion of the power for the measurement of the radiant exposure or flux of the incident electromagnetic radiation. Devices of the invention may include near field communication components, for example, for enabling readout by an external device, such as a computer or mobile device.