This article proposes a flexible, autonomous device for direct monitoring of the temperature in a rotating machine. The used temperature sensor is a platinum resistance thermometer. The sensor's power is supplied wirelessly using a flexible photovoltaic panel coupled with a DC-DC converter which is placed in the rotating instrumentation. As a whole, the system is characterized with a pulsed LED light on the photovoltaic panel simulating the machine's rotation. Finally, the light emitted by a LED is retrieved from a distance using a photometer placed at the temperature sensor output. Experimental results are presented in this article to show system efficiency.