Development of a microfabrication technology for microcantilever-based detection modules in Lab-On-a-Chip application

Nowadays, the development of Lab-On-a-Chip (LOC) technologies has opened up new perspectives in the field of personalized diagnosis and treatment, by taking advantage of reduced size, low volume requirement for samples, and rapid analysis. In particular, MEMS, microelectronics and nanobiotechnology are enabling technologies for the realization of biosensors by combining both microsystems for sample handling, signal read-out and functionalization methodologies able to detect specific bioaffinity reactions. In this frame, LOC technologies are a powerful tool to perform a wide range of proteomic and genomic tests starting from fluid biological samples such as blood or saliva. In this work we present the design and realization of the first prototypes for testing a technology for LOC detection module for pre-screenings of autoimmune diseases such as multiple sclerosis and rheumatoid arthritis in point-of-care applications. This module is based on arrays of silicon microcantilevers, which are typically suspended beams realised with MEMS fabrication technologies, suitable for biological and chemical sensing. Sensitivity to specific analytes can be achieved by coating the beam surface with proper films, able to selectively bind a particular target molecule. A self assembled monolayer (SAM) of known ss-DNA probes will represent the functional layer. The following hybridization of the complementary target sequence induces a differential stress between the top and the bottom surfaces of a cantilever, driving the deflection of the beam. The proposed technological approach is based on the fabrication of microcantilevers starting from Silicon-On-Insulator (SOI) substrates, allowing an extreme reduction in the thickness of the beams (380 nm), parameter that is related to the sensitivity of the overall biosensor. Both analytical and finite element analysis have been performed, focused on the general validation of the approach and on the design optimization respectively. Preliminary results on the fabrication and testing will be also highlighted