An Artificial Nose Based on Microcantilever Array Sensors

Abstract

We used microfabricated cantilever array sensors for an artificial nose setup. Each cantilever is coated on its top surface with a polymer layer. Volatile gaseous analytes are detected by tracking the diffusion process of the molecules into the polymer layers, resulting in swelling of the polymer layers and therewith bending of the cantilevers. From the bending pattern of all cantilevers in the array, a characteristic 'fingerprint' of the analyte is obtained, which is evaluated using principal component analysis. In a flow of dry nitrogen gas, the bending of the cantilevers is reverted to its initial state before exposure to the analyte, which allows reversible and reproducible operation of the sensor. We show examples of detection of solvents, perfume essences and beverage flavors. In a medical application, the setup provides indication of presence of diseases in patient's breath samples.

A gas micromechanical sensor based on surface plasmons resonance

“…The most common way of exciting SP is the attenuated total reflection technique based on an evanescent light wave coupling through a prism, for instance in the Kretschmann-Raether configuration, [13][14][15][16][17][18]. In this case, the SPR incident angle, wherein the resonance conditions are fulfilled, can be calculated as follow: (2) , where n prism is index of the prism and ε r (ω) is the real part of the dielectric function of the metal.…”

“…The most common principles of chemical transducing use either surface stress change/volume dilatation occurring as a result of selective immobilization of target molecules on the cantilever, or an environment temperature change induced by exothermic/endothermic chemical reactions to be detected, [1][2][3][4][5][6][7][8][9][10].…”

“…Let us notice that, in both cases, the sensitivity of the cantilever based transducer is proportional to the square of the cantilever length, and it depends on the nature of the transducing interaction, and the cantilever design parameters, [1][2][3][4][5][6][7][8][9][10][11]. Finally, the chemical sensing is achieved by monitoring the transducer mechanical response.…”

“…Commonly, in sensing applications, optical readout techniques are preferred because it provides higher signal-to-noise and ratio much faster response time than the electronic methods, [1][2][3][4][5][6][7][8][9][10][11]. In addition, the optical readout means are insensitive to electromagnetic noise and they can function reliably in aggressive environment (for example, at a high level of radioactivity and at a high temperature).…”

High Precision Electrohydrodynamic Printing of Polymer Onto Microcantilever Sensors

“…Integration of multiple polymers onto multiple cantilevers in an array, without cross contamination, is challenging and requires micrometer control over the size and position of the functional layer. Individual cantilevers in arrays can be functionalized with polymer using drop-coating, microarray spotting pins, immersion in capillaries, and inkjet printing [21]- [23], [26]. These techniques are limited to resolutions in the hundreds of micrometers and lack the ability to print patterns or precisely locate polymer onto microcantilever sensors.…”