Transferrin Electronic Detector for Iron Disease Diagnostics

Field effect transistor (FET) structure with suspended bridge shows the ability to detect proteins with very high sensitivity. This sensor is tested for the transferrin, a specific blood plasma protein, relevant in iron disease diagnostic. This system is based on field effect transistor with a suspended bridge used as a gate electrode. The sensitive layer is made of silicon nitride as in the ISFET (ion sensitive field effect transistor) technology. The surface micro-technology ensures a small height suspended-bridge (0.5 mum) composed of poly-silicon insulated with silicon nitride. To improve sensitivity and to limit biofouling, proteins are selected by antibodies covalently bound to organic layers. The specific charge of the fixed transferrins translates the transistor transfer characteristics. For low concentration, resulting shift is important and confers a good sensitivity to our electronic transducer.