© 2015, Wydawnictwo SIGMA - N O T Sp. z o.o. All rights reserved. Sensing on the microscale using microelectromechanical systems (MEMS) has established itself commercially as one of the dominant world-wide sensing technologies, providing commercialised sensing solutions for pressure, inertia, temperature, as well as for more challenging applications in remote infrared imaging and energy harvesting. However, to date MEMS has not delivered any commercially successful chem/bio sensor, even though it has been established for some time that microcantilever-based sensing can detect chem/bio agents at the level of single molecules or even zeptograms (10-21 g). The widespread application of this class of sensors has been largely impeded by the lack of a technology capable of performing high-resolution measurements of large arrays of MEMS devices. We demonstrate a technology capable of filling that need that is based on MEMS suspended microcantilevers and an on-chip optical read-out, and show an implementation of an effective toluene sensor.