Micro/nanomechanical resonators for distributed mass sensing with capacitive detection (original) (raw)
Related papers
Sensing applications of micro- and nanoelectromechanical resonators
Proceedings of the Institution of Mechanical Engineers, Part N: Journal of Nanoengineering and Nanosystems, 2007
The sensitivity of micro- and nanoscale resonator beams for sensing applications in ambient conditions was investigated. Micro-electromechanical (MEMS) and nanoelectromechanical systems (NEMS) were realized using silicon carbide (SiC) and polycrystalline aluminium nitride (AlN) as active layers on silicon substrates. Resonant frequencies and quality factors in vacuum as well as in air were measured. The sensitivity behaviour under ambient conditions with a mass loading in the range of picogram (pg) was verified and measurements with biological mass loading were performed. In addition, the sensitivity to pressure variations was analysed.
Microelectronic Engineering, 2002
We have fabricated micromechanical single crystal silicon bridges for mass sensor application using silicon-on-insulator (SOI) substrate. Bridge structures, i.e. both-ends-supported beams, have a 6.3-times higher fundamental resonance frequency compared to one-end-supported cantilevers and, thus, have a higher mass sensitivity. The resonators are driven electrostatically and read out optically by means of the laser beam deflection method. Measurements of the resonator oscillation are in good agreement with the calculated fundamental resonance frequency of 262 kHz in the case shown; however, further improvements for a higher quality factor are required.
Capacitive Based Micromachined Resonators for Low Level Mass Detection
Micromachines
Advancements in microfabrication technologies and novel materials have led to new innovations in miniaturized gas sensors that can identify miniscule changes in a complex environment. Micromachined resonators with the capability to offer high sensitivity and selectivity in array integration make mass loading a potential mechanism for electronic nose applications. This paper investigates the mass sensing characteristics of progressive capacitive based micromachined resonators as potential candidates for volatile organic compound detection where also there is a need for miniaturized array configuration. In this paper, a detailed investigative review of the major three geometric designs of capacitive based micromachined resonators, namely, the microcantilever, the microbridge and the clamped membrane sensors is performed. Although many reviews are present in literature regarding mass sensors, however there is a gap in the literature regarding the common capacitive based micromachined m...
Design, fabrication and testing of a novel MEMS resonator for mass sensing applications
Microelectronic Engineering, 2007
Micro- and nanoelectromechanical systems (MEMS/NEMS) have a high potential for mass sensing application. By miniaturization of the dimensions, higher and higher sensitivities can be achieved. Here we are presenting finite element modelling and optimization of a free–free beam type mechanical resonator. The hope is to optimize the mass sensitivity by increasing the Q-factor, which in turn, decreases the frequency noise
Nanotechnology, 2001
A simple linear electromechanical model for an electrostatically driven resonating cantilever is derived. The model has been developed in order to determine dynamic quantities such as the capacitive current flowing through the cantilever-driver system at the resonance frequency, and it allows us to calculate static magnitudes such as position and voltage of collapse or the voltage versus deflection characteristic. The model is used to demonstrate the theoretical sensitivity on the attogram scale of a mass sensor based on a nanometre-scale cantilever, and to analyse the effect of an extra feedback loop in the control circuit to increase the Q factor.
Nanotechnology, 2005
A resonator system has been fabricated directly on a pre-processed CMOS chip. The system is to be used for high sensitivity mass sensing applications in air and vacuum. The resonator system, corresponding of a cantilever and structures for electrostatic actuation and capacitive read-out, have been defined by electron beam lithography on top of a charge and radiation sensitive CMOS layer in predefined areas as a post-process step. This has been accomplished without affecting the electronic properties of the pre-processed CMOS circuits. The subsequent etching steps to fully release the cantilevers have been obtained without stiction of the cantilevers to the substrate. Cantilevers are driven at their mechanical resonance in a lateral mode, and the frequency is monitored by capacitive read-out on the chip. CMOS integration enables signal detection directly on the chip, which radically decreases the parasitic capacitances. Consequently, low-noise electrical measurements with a very high mass sensitivity are obtained. Fabricated resonator systems were characterized to have resonance frequencies of approximately 1.49 MHz, which is in good agreement with a theoretical estimation of 1.41 MHz. The theoretical mass resolution, ∂m/∂ f , is approximately 17 ag Hz −1 , using a Young modulus value of 160 GPa.
CMOS micromachined capacitive cantilevers for mass sensing
Journal of Micromechanics and Microengineering, 2006
In this paper, we present the design, fabrication and characterization of the CMOS micromachined cantilevers for mass sensing in the femtogram range. The cantilevers consisting of multiple metal and dielectric layers are fabricated after completion of a conventional CMOS process by dry etching steps. The cantilevers are electrostatically actuated to resonance by in-plane electrodes. The mechanical resonant frequency is detected capacitively with on-chip circuitry, where the modulation technique is applied to eliminate capacitive feedthrough from the driving port and to lessen the effect of flicker noise. The highest resonant frequency of the cantilevers is measured at 396.46 kHz with a quality factor of 2600 at 10 mTorr. The resonant frequency shift after deposition of a 0.1 µm SiO 2 layer is 140 Hz, averaging 353 fg Hz −1 .
Self-oscillation conditions of a resonant nanoelectromechanical mass sensor
Journal of Applied Physics, 2009
This article presents a comprehensive study and design methodology of co-integrated oscillators for nano mass sensing application based on resonant Nano-Electro-Mechanical-System (NEMS). In particular, it reports the capacitive with the piezoresistive transduction schemes in terms of the overall sensor performance. The developed model is clearly in accordance with the general experimental observations obtained for NEMS-based mass detection. The piezoresistive devices are much sensitive (up to 10 zg/√Hz) than capacitive ones (close to 100 zg/√Hz) since they can work at higher frequency. Moreover, the high doped silicon piezoresistive gauge, which is of a great interest for very large scale integration displays similar theoretical resolution than the metallic gauge already used experimentally.