Amorphous silicon sensors for Lab-on-Chip applications

In this work, amorphous silicon (a-Si:H) based devices have been utilized as active sensors in Lab- on-Chip systems. The basic structure is a p-type a-SiC:H (amorphous silicon carbide)/ i-type a-Si:H/ n-type a-Si:H stacked structure deposited on a glass substrate covered with a transparent conductive oxide. The a-Si:H devices implement both on-chip light detection for quantitative analysis of biomolecules and spatial monitoring of temperature for thermal treatment of analytes. As photodiodes, the a-Si:H structures allow to quantify the fluorescence of labeled or naturally fluorescent molecules. In particular, detection of labeled DNA and micotoxins have been performed with detection limit around 10 nmol/l and 0.1ng, respectively. As temperature sensor, the diodes are integrated in a system implementing the Polymerase Chain Reaction technique for DNA amplification. Electrical characterization of the diodes biased with a constant forward current shows a sensitivity of -3.3 mV/K demonstrating their suitability in this application.