Amorphous silicon photosensors for food quality control applications

In this paper we present an innovative, low cost and portable detection system for food quality control based on Thin Layer Chromatography method. The operating principle relies on the real-time monitoring of the chromatographic run through the measurement of the photocurrent induced in amorphous silicon (a-Si:H) photosensors by naturally fluorescent molecules present in the investigated sample. The integration in the system of the array of a-Si: H photosensor allows to achieve a sensitive and compact system without external optics for focusing the fluorescent light. The presented system was designed for detection and quantification of Ochratoxin A (OTA), a toxin due to food contamination by fungi. Tests for the detection of OTA were successfully performed achieving a minimum detectable quantity of 0.2 ng for both red wine extract and OTA standard solutions. Taking into account a 90 % of extraction efficiency and a volume of 2 mu l which can be spotted on the HPTLC plate, we infer that a volume of only 5.5 ml of red wine is necessary to compare OTA level with the law limit.