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Micro-nano cantilever based detection of small electromagnetic forces

English title Micro-nano cantilever based detection of small electromagnetic forces
Applicant Popovic Radivoje
Number 110923
Funding scheme SCOPES
Research institution Institut de microtechnique EPFL - STI - IMT
Institution of higher education EPF Lausanne - EPFL
Main discipline Microelectronics. Optoelectronics
Start/End 01.09.2005 - 31.03.2009
Approved amount 71'990.00
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All Disciplines (3)

Discipline
Microelectronics. Optoelectronics
Information Technology
Electrical Engineering

Keywords (4)

cantilevers; magnetic tip; piezoresistors; force sensitivity

Lay Summary (English)

Lead
Lay summary
Microcantilevers are very attractive as central components for a number of extremely sensitive new-generation sensors. For detection of cantilever deflection various mechanisms are used (optical, capacitive, piezoresistive, piezoelectric). Among all these methods, piezoresistive is the most compact one and allows fabrication of stand-alone (autonomous) miniature sensors. Our goal is to study possibilities of detection of small electromagnetic forces using microcantilevers with built-in piezoresistive sensors. In order to determine minimum detectable force it is necessary to study (a) the noise mechanisms inherently related with cantilevers (mechanical-thermal noise due to Brownian motion, adsorption-desorption noise, thermal noise due to temperature fluctuations of the microcantilever), (b) the noise related with piezoresistors (1/f noise, thermal noise, generation-recombination noise), (c) the influence of these noise mechanisms on fluctuations of resonant frequency of the detection oscillatory cicuit (which requires the calculation of phase noise in self-oscillatory circuits).
The experimental part of this project consists in the fabrication of microcantilever with a miniature magnet on the cantilever tip. The magnetic tip will be realized using sputtering technique or by deposition of epoxy powder with magnetic particles. Measurement of small forces will be done using the interaction between the miniature permanent magnets and currents in Au conductor lines on Si-SiO2. Next, we plan to perform measurements of noise caused by the above stated mechanisms. Special attention will be payed to measurement of 1/f noise in piezoresistors.
The results obtained during the study of noise generation mechanisms in microcantilevers and determination of the phase noise in detection oscillatory circuit should enable us to theoretically determine minimum detectable force. The above experiments for measuring of small forces and noise will serve for verification of theoretical results. Finally, this will lead us to design an optimal system for detection of small forces using magnetic microcantilevers.
Direct link to Lay Summary Last update: 21.02.2013

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