Flexible X-Ray Detector Based on the Seebeck Effect

Basically, there are two main methods to detect the energy and intensity of an X-ray beam, known as the direct method and the indirect method. In the direct method, the X-rays are absorbed by a pn junction or a photoconductive layer and directly converted into an electric signal. In the indirect method, a scintillator absorbs the X-rays, and converts them into visible or near-visible light. The visible light is then converted to an electrical signal by means of a photodetector. In this article, a theoretical and experimental basis for a new X-ray detector based in the conversion of X-rays into thermal energy is presented. The detector follows the indirect method approach, once the thermal energy is converted into an electrical signal by the Seebeck effect. The detector does not need high operating voltages as the ones needed by the detectors based on the direct method, and it shows higher efficiency in the energy conversion than the X-ray detectors based in the indirect method. Moreover, this technique allows the fabrication of X-ray detectors on flexible substrates, not possible with the other methods. Finally, when disposed into a matrix arrangement will allow the construction of image sensors for digital radiography, reducing the discomfort caused by the rigid flat panel sensors in intraoral radiology, for example.