Cantilever systems for the next generation of biomechanical sensors

PhD ceremony: Mr. M. Lazzarino, 9.00 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Cantilever systems for the next generation of biomechanical sensors

Promotor(s): prof. P. Rudolf

Faculty: Mathematics and Natural Sciences

In my thesis work I investigated alternative geometries of nanomechanical oscillators to be employed as biomolecular sensors. Simple mechanical oscillators, such as cantilevers and double clamped beams have been deeply investigated in the last decade and single molecule sensitivity was demonstrated. However, beside few marginal exceptions, the proof of principle demonstrations did not yet evolve into commercial devices. Alternative geometries can, in principle, improve the simple micromechanical systems studied so far, with more complex transfer functions suitable to operate also in demanding environments.

The thesis work was divided in two major sections.

In the first section twin cantilevers are discussed. Couples of cantilevers facing each other and separated by a nanometer gap may change their resonance response when one or more molecules are absorbed in the gap. Two different geometries have been fabricated and tested. One, with identical cantilevers, takes advantage of the shift in resonance frequency occurring upon molecular detection; the second with asymmetrical cantilevers, uses the shortest one to actuate the motion of the longer one through a molecular link.

In the second part the structure of the twin cantilevers is the starting point for creating a spatially confined chemical reaction in the gap between two cantilevers facing each other. This original process is extremely precise and represents an important milestone towards the future realization of complex micro- and nanomechanical systems for biomolecular detection.