Prototyping of a Microsensor for Organic Vapours and Solutions

The cost and requirement of special devices and clean room are limitations for microfabrication technique. This paper addresses the low cost method for prototyping and fabrication of micro-chemisensor for the detection of organic molecules. Porous silicon layer is fabricated on the (100) plane of p-type silicon wafer using metal assisted chemical etching method. According to the characterization results the metal assisted chemical etching method gives good porous morphological structure which is suitable for sensor fabrication. The microelectrodes for the sensor were prepared on the porous layer using cost effective microfabrication technique. The electrode patterns to be fabricated are designed using free design software to generate the high resolution image file. Transparency-based photo-masks are made by offset printing technique which is very cost effective for rapid prototyping. The contact mask aligner provides the transferring of pattern onto the substrates. The fabricated sensor exhibits very sensitive and reversible response during the real-time measurements of capacitance in ethanol vapour. The change in surface charges upon ethanol infiltration into the porous structure produces the response in electrical properties of sensor