Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Fabrication of mass sensor based on submicron cantilevers on CMOS substrates

A mass sensor based on a resonating cantilever integrated monolithicaly with the CMOS readout circuitry has been achieved.

Mass detection principle is based on the shift of the cantilever resonance frequency, produced when the mass to be measured is deposited in the moving end of the cantilever. The smaller the cantilever, the smaller its mass and, consequently, the larger its mass sensitivity. In this project, cantilevers with typical dimensions of 20 microns in length, 600 nm in thickness and 400 nm in width, give mass sensitivities in the ag/Hz range. Typical applications can be found in bio analysis: detection of single antibody-antigen interactions.

Technology compatibilization of standard CMOS processes with non-standard nanolitography techniques has been demonstrated. This means that all the procedures for combining nanotransducers with readout control and processing microelectronic CMOS circuitry have been stabilised and tested. Thus, the sensitivity of the mass sensors or whatever sensor which sensitivity increases by scaling down dimensions, can be potentially improved by fabricating the transducer as small as the nanolithigraphic technique will allow.

The electrostatic excitation and capacitive readout scheme used in this project has demonstrated to be the most simple technological option for monolithic integration of transducer and circuitry. The same strategy can be extended to the field of RF-MEMS, where low compliant mechanical resonators can be combined with microelectronic circuitry, to integrate blocs of communications systems like oscillators, switches, filters or mixers, that traditionally are implemented using electronic devices.

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Reported by

Department of Electronic Engineering
Edifici Q. Escola Tècnica Superior d’Enginyeria
08193 Bellaterra (Barcelona)