Casimir and Van der Waals Effects on Voltage Response of Electrostatically Actuated MEMS/NEMS Plates

Author(s):  
Dumitru I. Caruntu ◽  
Reynaldo Oyervides ◽  
Valeria Garcia

This paper deals with electrostatically actuated MEMS plates. The model consists of a flexible MEMS plate above a parallel ground plate. An AC voltage of frequency near natural frequency of the plate provides the electrostatic force that actuates the flexible MEMS plate. This leads to parametric resonance. The effect of Casimir and/or van der Waals forces on the voltage-amplitude response of the plate is investigated.

Author(s):  
Dumitru I. Caruntu ◽  
Reynaldo Oyervides ◽  
Valeria Garcia

This paper deals with electrostatically actuated Micro-Electro-Mechanical Systems (MEMS) circular plates. The system consists of a flexible circular plate with the edge fixed above a parallel ground plate. The forces acting on the MEMS plate are the electrostatic, damping, and elastic restoring force. In this work Casimir and/or van der Waals forces are neglected, since they are significant for gaps less than one micron and/or 50 nanometers, respectively. The electrostatic force is given by a soft Alternate Current (AC) harmonic voltage between the two plates. The electrostatic force leads the flexible plate into vibration. The assumption of axisymmetrical vibrations is valid in this work. The AC frequency is near natural frequency of the flexible circular plate. Since the electrostatic force is proportional to the square of the voltage, this results in an electrostatic force of frequency twice the natural frequency. Therefore the system experiences a parametric resonance. The partial differential equation of motion is non-dimensionalized. Next the resulting lumped parameters are found from a typical MEMS circular plate resonator. Reduced Order Model (ROM) is the method of investigation used in this work, specifically two terms ROM. Numerical simulations are conducted to predict the voltage response of the system. The effects of frequency and damping on the response are predicted as well. MEMS circular plate systems are excellent candidates for resonator sensors, i.e. sensors functioning at resonance. They are capable of detecting cells, viruses, as well as any microparticles provided the plates are coated for such recognition.


Author(s):  
Dumitru I. Caruntu ◽  
Reynaldo Oyervides

This paper investigates parametric resonance of electrostatically actuated MEMS circular plates for resonator sensing applications. The system consists of a clamped circular elastic plate over a ground plate. Soft AC voltage of frequency near natural frequency of the plate gives the electrostatic force that leads the elastic plate into vibration, more specifically into parametric resonance which can be used afterwards for biosensing purposes. Frequency response and corresponding bifurcations are reported. The effects of damping and voltage are predicted.


Author(s):  
Dumitru I. Caruntu ◽  
Reynaldo Oyervides

This paper utilizes Reduced Order Model (ROM) method to investigate the voltage-amplitude response of electrostatically actuated M/NEMS clamped circular plates. Soft AC voltage at frequency near half natural frequency of the plate is used. This results in primary resonance of the system. The effects of nonlinearities of the system including pull-in instability on the voltage-amplitude response are investigated. Namely, the effects of detuning frequency, damping, Casimir force, and van der Waals force on the voltage response of clamped circular plates are reported. Casimir and van der Waals forces are found to have significant effects on the response of clamped circular plates and must be considered to accurately model and predict the behavior of the system.


Author(s):  
Dumitru I. Caruntu ◽  
Reynaldo Oyervides

This paper investigates the voltage–amplitude response of soft alternating current (AC) electrostatically actuated micro-electro-mechanical system (MEMS) clamped circular plates for sensing applications. The case of soft AC voltage of frequency near half natural frequency of the plate is considered. Soft AC produces small to very small amplitudes away from resonance zones. Nearness to half natural frequency results in primary resonance of the system, which is investigated using the method of multiple scales (MMS) and numerical simulations using reduced order model (ROM) of seven terms (modes of vibration). The system is assumed to be weakly nonlinear. Pull-in instability of the voltage–amplitude response and the effects of detuning frequency and damping on the response are reported.


Author(s):  
Dumitru I. Caruntu ◽  
Julio Beatriz ◽  
Jonathan Perez

Abstract This paper deals with voltage-amplitude response of superharmonic resonance of second order of electrostatically actuated clamped MEMS circular plates. A flexible MEMS circular plate, parallel to a ground plate, and under AC voltage, constitute the structure under consideration. Hard excitations due to voltage large enough and AC frequency near one fourth of the natural frequency of the MEMS plate resonator lead the MEMS plate into superharmonic resonance of second order. These excitations produce resonance away from the primary resonance zone. No DC component is included in the voltage applied. The equation of motion of the MEMS plate is solved using two modes of vibration reduced order model (ROM), that is then solved through a continuation and bifurcation analysis using the software package AUTO 07P. This predicts the voltage-amplitude response of the electrostatically actuated MEMS plate. Also, a numerical integration of the system of differential equations using Matlab is used to produce time responses of the system. A typical MEMS silicon circular plate resonator is used to conduct numerical simulations. For this resonator the quantum dynamics effects such as Casimir effect are considered. Also, the Method of Multiple Scales (MMS) is used in this work. All methods show agreement for dimensionless voltage values less than 6. The amplitude increases with the increase of voltage, except around the dimensionless voltage value of 4, where the resonance shows two saddle-node bifurcations and a peak amplitude significantly larger than the amplitudes before and after the dimensionless voltage of 4. A light softening effect is present. The pull-in dimensionless voltage is found to be around 16. The effects of damping and frequency on the voltage response are reported. As the damping increases, the peak amplitude decreases. while the pull-in voltage is not affected. As the frequency increases, the peak amplitude is shifted to lower values and lower voltage values. However, the pull-in voltage and the behavior for large voltage values are not affected.


Author(s):  
Dumitru I. Caruntu ◽  
Reynaldo Oyervides

This paper deals with Casimir and van der Waals effects on the frequency response of parametric resonance of electrostatically actuated NEMS circular plates for bio-sensing applications. The bio-NEMS resonator consists of a clamped circular elastic plate over a fixed electrode plate. A soft AC voltage of frequency near natural frequency between the plates gives an electrostatic force that leads the elastic plate into vibration which leads to parametric resonance that can be used afterwards for biosensing purposes. Frequency response and the effects of Casimir, and van der Waals forces on the response are reported.


Author(s):  
Christopher Reyes ◽  
Dumitru I. Caruntu

This paper investigates the dynamics governing the behavior of electrostatically actuated MEMS cantilever resonators. The cantilever is held parallel to a ground plate (electrode) with an AC voltage between the plate and the electrode causing the electrostatic actuation (excitation). For the purposes of this paper this is soft excitation. The frequency of the excitation is near the natural frequency of the cantilever leading to what is known as parametric resonance. The electrostatic force in the problem investigated throughout the paper is nonlinear in nature and includes the fringe effect. Two methods are used in investigating this problem: the method of multiple scales (MMS) and the homotopy perturbation method (HPM). The two methods work well for small non-linearities and small amplitudes. The influence of voltage, fringe, damping, Casimir, and Van der Waals parameters will be investigated in this paper using MMS and HPM as a means of verifying the results obtained.


Author(s):  
Dumitru I. Caruntu ◽  
Le Luo

This paper deals with electrostatically actuated Carbon Nano-Tubes (CNT) cantilevers using Reduced Order Model (ROM) method. Forces acting on the CNT cantilever are electrostatic, van der Waals, and damping. The van der Waals forces are significant for values of 50 nm or lower of the gap between the CNT and the ground plate. As both forces electrostatic and van der Waals are nonlinear, and the CNT electrostatic actuation is given by AC voltage, the CNT undergoes nonlinear parametric dynamics. The Method of Multiple Scales (MMS), and ROM are used to investigate the system under soft excitations and/or weak nonlinearities. The frequency-amplitude and frequency-phase behaviors are found in the case of parametric resonance.


Author(s):  
Dumitru I. Caruntu ◽  
Julio Beatriz

Abstract This paper investigates the voltage-amplitude response of superharmonic resonance of fourth order of electrostatically actuated clamped MEMS circular plates. The system consists of flexible MEMS circular plate parallel to a ground plate. Hard excitations (voltage large enough) and AC voltage of frequency near one eight of the natural frequency of the MEMS plate resonator lead it into a superharmonic resonance. Hard excitations produce actuation forces large enough to produce resonance away from the primary resonance zone. There is no DC component in the voltage applied. The partial differential equation of motion describing the behavior of the system is solved using two modes of vibration reduced order model (ROM). This model is solved through a continuation and bifurcation analysis using the software package AUTO 07P which produces the voltage-amplitude response (bifurcation diagram of the system, and a numerical integration of the system of differential equations using Matlab that produces time responses of the system. Numerical simulations are conducted for a typical MEMS silicon circular plate resonator. For this resonator the quantum dynamics effects such as Casimir effect or Van der Waals effect are negligible. Both methods show agreement for the entire range of voltage values and amplitudes. The response consists of an increase of the amplitude with the increase of voltage, except around the value of 4 of the dimensionless voltage where the resonance shows two saddle-node bifurcations and a peak amplitude about ten times larger than the amplitudes before and after the dimensionless voltage of 4. The softening effect is present. The pull-in voltage is reached at large values of the dimensionless voltage, namely about 14. The effects of damping and frequency on the voltage response are reported. As the damping increases, the peak amplitude decreases for the resonance. However, the pull-in voltage is not affected. As the frequency increases, the resonance zone is shifted to lower voltage values and lower peak amplitudes. However, the pull-in voltage and the behavior for large voltage values are not affected.


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