In this paper, we present a new method to measure light intensity in a floating body partially depleted SOI MOSFET. The photo-generated charge density in the MOSFET is converted into a charge pumping frequency needed to maintain the drain current at a constant value. This new approach contrasts with conventional techniques that rely on an accurate drain current evaluation. According to our measurements, flux densities as low as 2 mW/m2 were obtained using a regular SOI MOSFET, thus confirming the potentials of this approach. © 2007 Elsevier Ltd. All rights reserved.