Detection of Small Toxin Molecules by Si Photovoltaic Integrated Circuit

Abstract

We propose a new type of photosensitive biosensor with a CMOS compatible Si photovoltaic integrated circuit, for the high-sensitive detection of small mycotoxin molecules requiring competitive assay approach. In this work, a photodiode is connected to the gate of a field effect transistor (FET) so that the open circuit voltage (VOC) of the illuminated photodiode is transferred into the drain/source current of the FET. The sensing scheme employs competitive binding of toxin molecules (within the sample solution) and toxin-BSA conjugates (immobilized on the photodiode surface) with Au-nanoparticle-labeled antibodies, followed by silver enhancement to generate opaque structures on the photodiode surface. As the amount of toxin increases, less opaque becomes the photodiode surface resulting in a higher VOC. By monitoring the channel current of the FET whose gate is driven by the VOC, quantitative detection of Aflatoxin B1 has been achieved in the range of 0∼15 ppb.