MEMS (Micro-Electro-Mechanical Systems) are very small systems with the size of few hundred micrometers that use both mechanical and electrical elements to achieve sensing or actuating functions.
As sensors, MEMS are particularly attractive in the food and agriculture sectors where specific and sensitive biosensors are required because they are sensitive due to their small size, and also because, today, the new technologies offer the possibility to implement them in an all-organic approach. Hence, they can be more functional by the integration of not expensive materials with specific properties (electrical, optical, mechanical, and chemical) allowing the tailor-made design of low-cost and fully-integrated biosensors operating uniquely.
A MEMS-based biosensor works generally in the following manner: a sensitive layer deposited on the top of a microcantilever, ensures the biological recognition, afterward, the detection of the analyte by the receptors of the sensitive layer creates a difference of stress between the sensitive layer and the microcantilever that results in the deformation of the microcantilever. But, to make it very sensitive it is important to reduce the rigidity of the microcantilever to obtain high deflection.
One original example developed at the BioSense Institute, uses the mechanical properties offered by the plastic substrates to fabricate flexible microcantilevers that can create high deflection. However, the resulting deflections cannot be read directly by the user and the sensor needs to be connected to a read out device.
One simple and effective solution developed at the Biosense Institute, consists in the integration of a piezoresistor at the clamp of the microcantilever that transforms the mechanical effect to an electrical value readable by the user.
The flexible MEMS-based biosensor, due to its small size and its flexibility, is then able to detect very small elements such as chemical molecules, bacterias and mycotoxin in low concentration while offering a read-out system adapted to the user.
One of the original concepts of biosensor developed and fabricated at the BioSense Institute uses laser-micromachined flexible organic substrate.