Piezoresistive Microcantilevers-Based Cocaine Biosensors

An aptamer-coated, piezoresistive, microcantilever-based biosensor has been fabricated and tested as presented here to measure the relative concentration of freebase cocaine in solution. Aptamers were used as the cocaine receptor due to their known high selectivity and affinity for the target molecules in buffered solutions. A Wheatstone bridge composed of four microcantilevers was utilized in converting the biological signal to an electrical signal. The approach here provides a prototype that will lead to a compact and low cost device that will be applicable for in-vivo applications. The performance of this sensor is demonstrated in an in-vitro experiment conducted by flowing a cocaine solution in distilled water over the microcantilever arrays. The response of the device had a limit of detection of 1 ng/ml, which is comparable to the conventional method of cocaine detection in the body performed using gas/liquid chromatography and mass spectrophotometry.