Cantilever based sensors are promising miniaturized sensing tools for bio-chemical applications . These micromechanical
sensors can be employed to sense very small amounts of dangerous substances like explosive molecules,
biological threats and hazardous compounds, both in air or liquid environment. In our project we focus on the
development of a new readout system for employing of this sensing technique for detection of explosives like TNT,
RDX and PETN, under the framework of the Xsense project.
At present available optical equipments for cantilever sensing are typically big and bulky, making the in situ employment
of this technology still very hard.
Here we present a novel approach to measure the absorption of masses on the cantilever surfaces by using a light,
compact, portable and high throughput optical device. Our setup is able to measure real time both the deflection of the
beams and their vibrational frequencies, employing the same laser source and the same photodetector.
The optical readout of cantilever-based sensors was re-designed and developed combining the technology of commercial
DVD-ROM readers  with polymer based holding substrates structured with UV-lithography or imprint technology.
Cantilever chips are clamped on a predefined holding substrate structured in SU-8 or in Cyclic Olefin Copolymer (COC),
while the DVD-ROM reader is placed 1 mm below the substrate.
The laser beam is collimated and focused on cantilevers with a 0.75 μm spot diameter and the reflected light is then
recorded using an astigmatism-based 4-quadrant photodetector.
The integration of the DVD-ROM reader with the on-substrate holding approach leads to a high throughput flexible
platform with easy auto-alignment and replacement of the cantilevers chips.
With this new on-substrate approach tens of chips can be placed on the Polymer holder and be read sequentially in a very
light and compact device.