Nanomechanical Biosensors

The aim of this research line is the development of highly sensitive nanomechanical-based biosensing platforms. We work on different approaches for the development of nanomechanical platforms based in specially designed micro-electromechanical systems (MEMs). Our work involves the MEMs design, fabrication (using standard silicon technology) and characterization, as well as the integration of the MEMs devices with a microfluidic system and an optical detection system, looking for final totally integrated lab-on-a-chip.

We are currently working in three different Nanomechanical platforms arrays of silicon microcantilevers (MC), arrays of optical waveguide microcantilevers (OWC) and hollow microbridges (HMB).

Arrays of silicon microcantilevers (MC)

Nanomechanical platform based on arrays of silicon microcantilevers (MC). We fabricate arrays of up to 20 microcantilevers with a low spring constant for the development of surface stress-based nanomechanical biosensors. A high integration of the system (palm size) is achieved by using an array of 20 VCSEL, and a 20 channel microfluidic cell. The microcantilevers movement is detected by using a large area PSD and a sequential switch of the lasers.

Arrays of optical waveguide microcantilevers (OWC)

Nanomechanical platform based on arrays of optical waveguide microcantilevers (OWC). We have introduced a new type of read-out technique based on silicon oxide microcantilevers acting as optical waveguides and operated in visible range, in order to achieve highly integrated microsystem. The principle of operation is based on the sensitivity of the energy transfer between two butt coupled waveguides to their misalignment with respect to each other. With the proposed method, sub-nanometer displacement of cantilever free end can be registered with a conventional photodetector, being possible to measure the surface stress change or the resonance frequency shift. No preliminary alignment or adjustment of the optical subsystem, except for light coupling, is required.

Hollow microbridges (HMB)

Nanomechanical platform based on hollow microbridges (HMB). We are fabricating arrays of four hollow microbridges for the development of resonance-based nanomechanical biosensors. The hollow microbridges allow performing the bioreaction inside the microbridge, reducing the damping effect when working with resonance-based biosensors under physiological conditions. The microbridge resonance shift is measured by using interferometric techniques.