Showing papers on "Piezoelectric sensor published in 2011"
TL;DR: In this paper, the authors discuss properties relevant to sensor applications, including piezoelectric materials that are commercially available and those that are under development, including oxyborate [ReCa4O (BO3)3] single crystals.
Abstract: Piezoelectric materials that can function at high temperatures without failure are desired for structural health monitoring and/or nondestructive evaluation of the next generation turbines, more efficient jet engines, steam, and nuclear/electrical power plants. The operational temperature range of smart transducers is limited by the sensing capability of the piezoelectric material at elevated temperatures, increased conductivity and mechanical attenuation, variation of the piezoelectric properties with temperature. This article discusses properties relevant to sensor applications, including piezoelectric materials that are commercially available and those that are under development. Compared to ferroelectric polycrystalline materials, piezoelectric single crystals avoid domain-related aging behavior, while possessing high electrical resistivities and low losses, with excellent thermal property stability. Of particular interest is oxyborate [ReCa4O (BO3)3] single crystals for ultrahigh temperature applications (>1000°C). These crystals offer piezoelectric coefficients deff, and electromechanical coupling factors keff, on the order of 3–16 pC/N and 6%–31%, respectively, significantly higher than those values of α-quartz piezocrystals (~2 pC/N and 8%). Furthermore, the absence of phase transitions prior to their melting points ~1500°C, together with ultrahigh electrical resistivities (>106 Ω·cm at 1000°C) and thermal stability of piezoelectric properties (< 20% variations in the range of room temperature ~1000°C), allow potential operation at extreme temperature and harsh environments.
634 citations
TL;DR: In this article, the voltage responses of ceramic-based piezoelectric fiber composite structures (PFCs) and polymer-based PFC strips, PVDF (polyvinylidene fluoride), were evaluated when subjected to various wind speeds and water droplets in order to investigate the possibility of energy generation from these two natural renewable energy sources for utilization in low power electronic devices.
Abstract: Piezoelectric materials have been in use for many years; however, with an increasing concern about global warming, piezoelectricity has gained significant importance in research and development for extracting energy from the environment. In this work the voltage responses of ceramic based piezoelectric fibre composite structures (PFCs) and polymer based piezoelectric strips, PVDF (polyvinylidene fluoride), were evaluated when subjected to various wind speeds and water droplets in order to investigate the possibility of energy generation from these two natural renewable energy sources for utilization in low power electronic devices. The effects of material dimensions, drop mass, releasing height of the drops and wind speed on the voltage output were studied and the power was calculated. This work showed that piezoelectric polymer materials can generate higher voltage/power than ceramic based piezoelectric materials and it was proved that producing energy from renewable sources such as rain drops and wind is possible by using piezoelectric polymer materials.
230 citations
TL;DR: In this paper, a new geometry for MEMS scale cantilever harvesters with low fundamental frequencies is proposed, modeled, and solved to show that such a structure would be able to vibrate near resonance at the micro-electro-mechanical scale.
Abstract: This paper addresses an issue in energy harvesting that has plagued the potential use of harvesting through the piezoelectric effect at the micro-electro-mechanical systems (MEMS) scale. Effective energy harvesting devices typically consist of a cantilever beam substrate coated with a thin layer of piezoceramic material and fixed with a tip mass tuned to resonant at the dominant frequency of the ambient vibration. The fundamental natural frequency of a beam increases as its length decreases, so that at the MEMS scale the resonance condition occurs orders of magnitude higher than ambient vibration frequencies, rendering the harvester ineffective. Here, we propose a new geometry for MEMS scale cantilever harvesters with low fundamental frequencies. A "zigzag" geometry is proposed, modeled, and solved to show that such a structure would be able to vibrate near resonance at the MEMS scale. An analytical solution is presented and verified against Rayleigh's method and is validated against a macroscale experiment. The analysis is used to provide design guidelines and parametric studies for constructing an effective MEMS scale energy harvesting device in the frequency range common to low frequency ambient vibrations, removing a current barrier.
120 citations
TL;DR: In this paper, a tire-road friction coefficient estimation approach is proposed which makes use of the uncoupled lateral deflection profile of the tire carcass measured from inside the tire through the entire contact patch.
Abstract: A tire-road friction coefficient estimation approach is proposed which makes use of the uncoupled lateral deflection profile of the tire carcass measured from inside the tire through the entire contact patch. The unique design of the developed wireless piezoelectric sensor enables the decoupling of the lateral carcass deformations from the radial and tangential deformations. The estimation of the tire-road friction coefficient depends on the estimation of slip angle, lateral tire force, aligning moment, and the use of a brush model. The tire slip angle is estimated as the slope of the lateral deflection curve at the leading edge of the contact patch. The portion of the deflection profile measured in the contact patch is assumed to be a superposition of three types of lateral carcass deformations, namely, shift, yaw, and bend. The force and moment acting on the tire are obtained by using the coefficients of a parabolic function which approximates the deflection profile inside the contact patch and whose terms represent each type of deformation. The estimated force, moment, and slip angle variables are then plugged into the brush model to estimate the tire-road friction coefficient. A specially constructed tire test rig is used to experimentally evaluate the performance of the developed estimation approach and the tire sensor. Experimental results show that the developed sensor can provide good estimation of both slip angle and tire-road friction coefficient.
119 citations
TL;DR: The shear piezoelectric behavior in relaxor-PbTiO(3) (PT) single crystals is investigated in regard to crystal phase, and the temperature and ac field drive stability for shear piesolectric responses are investigated.
Abstract: The shear piezoelectric behavior in relaxor-PbTiO3 (PT) single crystals is investigated in regard to crystal phase. High levels of shear piezoelectric activity, d15 or d24 >2000 pC N−1, has been observed for single domain rhombohedral (R), orthorhombic (O) and tetragonal (T) relaxor-PT crystals. The high piezoelectric response is attributed to a flattening of the Gibbs free energy at compositions proximate to the morphotropic phase boundaries, where the polarization rotation is easy with applying perpendicular electric field. The shear piezoelectric behavior of pervoskite ferroelectric crystals was discussed with respect to ferroelectric-ferroelectric phase transitions and dc bias field using phenomenological approach. The relationship between single domain shear piezoelectric response and piezoelectric activities in domain engineered configurations were given in this paper. From an application viewpoint, the temperature and ac field drive stability for shear piezoelectric responses are investigated. A temperature independent shear piezoelectric response (d24, in the range of −50°C to O-T phase transition temperature) is thermodynamically expected and experimentally confirmed in orthorhombic relaxor-PT crystals; relatively high ac field drive stability (5 kV cm−1) is obtained in manganese modified relaxor-PT crystals. For all thickness shear vibration modes, the mechanical quality factor Qs are less than 50, corresponding to the facilitated polarization rotation.
115 citations
TL;DR: The presented design concept, which can be applied to any engineering system with multimodal harmonic-vibrating skins, was applied to two case studies: an aircraft skin and a power transformer panel, showing larger power generation than EHskin without segmentation or unimodal EH skin.
Abstract: This paper presents an advanced design concept for a piezoelectric energy harvesting (EH), referred to as multimodal EH skin. This EH design facilitates the use of multimodal vibration and enhances power harvesting efficiency. The multimodal EH skin is an extension of our previous work, EH skin, which was an innovative design paradigm for a piezoelectric energy harvester: a vibrating skin structure and an additional thin piezoelectric layer in one device. A computational (finite element) model of the multilayered assembly-the vibrating skin structure and piezoelectric layer-is constructed and the optimal topology and/or shape of the piezoelectric layer is found for maximum power generation from multiple vibration modes. A design rationale for the multimodal EH skin was proposed: designing a piezoelectric material distribution and external resistors. In the material design step, the piezoelectric material is segmented by inflection lines from multiple vibration modes of interests to minimize voltage cancellation. The inflection lines are detected using the voltage phase. In the external resistor design step, the resistor values are found for each segment to maximize power output. The presented design concept, which can be applied to any engineering system with multimodal harmonic-vibrating skins, was applied to two case studies: an aircraft skin and a power transformer panel. The excellent performance of multimodal EH skin was demonstrated, showing larger power generation than EH skin without segmentation or unimodal EH skin.
82 citations
Patent•
15 Feb 2011TL;DR: In this article, a piezoelectric thin film element and a thin-film device are described, which can be produced in improved yields and can be used to improve the performance and efficiency of the PPI.
Abstract: Disclosed are a piezoelectric thin film element and a piezoelectric thin film device which have improved piezoelectric properties and high performance and can be produced in improved yields The piezoelectric thin film element ( 1 ) comprises: a substrate ( 10 ), and a piezoelectric thin film ( 40 ) which is arranged on the substrate ( 10 ), has at least one crystal structure represented by general formula (Na x K y Li z )NbO 3 (0≦x≦1, 0≦y≦1, 0≦z≦02, x+y+z=1) and selected from the group consisting of pseudo-cubic crystal, a hexagonal crystal, and an orthorhombic crystal, and contains an inert gas element at a ratio of 80 ppm or less by mass
72 citations
TL;DR: In this article, an active vibration control to suppress structural vibration of the smart hull structure was investigated based on optimized actuator configurations using anisotropic piezoelectric composite actuator, Macro-Fiber Composite (MFC), was used for the vibration control.
71 citations
TL;DR: In this paper, the von Karman nonlinear strain-displacement relationship is used to account for the large deflection of the plate, and two control algorithms are employed: classical displacement-velocity feedback control and robust H2 control.
Abstract: In this paper, large amplitude vibration control of functionally graded material (FGM) plates under thermal gradient and transverse mechanical loads using integrated piezoelectric sensor/actuator layers is investigated. In this regard, finite element formulation based on higher order shear deformation plate theory is developed. The von Karman nonlinear strain-displacement relationship is used to account for the large deflection of the plate. The material properties of FGM are assumed to be temperature-dependent and graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents. The temperature field is assumed to be constant in the plane and varied only in the thickness direction of the plate. In order to control the large amplitude vibration of the plate, two control algorithms are employed: classical displacement-velocity feedback control and robust H2 control. Also, the uncertainty which arises from external disturbances (low-frequenc...
68 citations
TL;DR: A novel approach developed for optimizing the location of piezoelectric actuators for vibration suppression of flexible structures by employing a novel numerical stochastic optimization algorithm and three multi-layer perceptron neural networks.
Abstract: The problem of positioning of actuators and sensors on smart materials has been a point of interest in recent years. This is due to the fact that in many practical applications there are limitations in space, weight, etc. of the smart structures, which make the problem of positioning more complex. In addition, it is required that the actuators/sensors have the best possible performance. The development of smart structures technology in recent years has provided numerous opportunities for vibration control applications. The use of piezoelectric ceramics or polymers has shown great promise in the development of this technology. The employment of piezoelectric material as actuators in vibration control is beneficial because these actuators only excite the elastic modes of the structures without exciting the rigid-body modes. This is important since very often only elastic motions of the structures are needed to be controlled. The purpose of this paper is to introduce a novel approach developed for optimizing the location of piezoelectric actuators for vibration suppression of flexible structures. A flexible fin with bonded piezoelectric actuators is considered in this study. The frequency response function (FRF) of the system is then recorded and maximization of the FRF peaks is considered as the objective function of the optimization algorithm to find the optimal placement of the piezoelectric actuators on the smart fin. Three multi-layer perceptron neural networks are employed to perform surface fitting to the discrete data generated by the finite element method (FEM). Invasive weed optimization (IWO), a novel numerical stochastic optimization algorithm, is then employed to maximize the weighted summation of FRF peaks. Results indicate an accurate surface fitting for the FRF peak data and an optimal placement of the piezoelectric actuators for vibration suppression is achieved.
66 citations
TL;DR: In this article, a Lamb wave mode decomposition technique using concentric ring and circular PZTs is proposed to identify individual Lamb wave modes and the subsequent data interpretation are often difficult due to the dispersive and multimodal natures of Lamb waves.
TL;DR: In this paper, a finite element formulation based on higher order shear deformation plate theory is developed to analyze nonlinear natural frequencies, time and frequency responses of functionally graded plate with surface-bonded piezoelectric layers under thermal, electrical and mechanical loads.
TL;DR: The numerical simulation shows that sufficient vibration suppression can be achieved by means of the proposed Particle Swarm Optimization method.
Abstract: Research highlights? We design a vibration control mechanism for a beam with bonded piezoelectric sensors and actuators. ? We apply three different variants of the Particle Swarm Optimization for the vibration control of the beam. ? We use a linear feedback control law and a quadratic cost function. ? We compare the results of the proposed method with the results of a Genetic Algorithm and of a Differential Evolution algorithm. ? We conclude that sufficient vibration suppression can be achieved by means of Particle Swarm Optimization. This paper presents the design of a vibration control mechanism for a beam with bonded piezoelectric sensors and actuators. The mechanical modeling of the structure and the subsequent finite element approximation are based on the classical equations of motion, as they are derived from Hamilton's principle, in connection with simplified modeling of the piezoelectric sensors and actuators. One nature-inspired intelligence method, the Particle Swarm Optimization, is used for the vibration control of the beam. Three different variants of the Particle Swarm Optimization were tested, namely, the simple Particle Swarm Optimization, the inertia Particle Swarm Optimization and the Constriction Particle Swarm Optimization. A linear feedback control law and a quadratic cost function are used, so that the results are comparable with the classical linear quadratic regulator approach. The same problem has been solved with two other stochastic based optimization algorithms, namely a Genetic Algorithm and a Differential Evolution and the results are used for comparison. The numerical simulation shows that sufficient vibration suppression can be achieved by means of this method.
TL;DR: In this article, the active aeroelastic flutter characteristics and vibration control of supersonic beams applying the piezoelectric material are studied further using the assumed mode method.
Abstract: The active vibration control of all kinds of structures by using the piezoelectric material has been extensively investigated. In this paper, the active aeroelastic flutter characteristics and vibration control of supersonic beams applying the piezoelectric material are studied further. The piezoelectric materials are bonded on the top and bottom surfaces of the beams to act as the actuator and sensor so that the active aeroelastic flutter suppression for the supersonic beams can be conducted. The supersonic piston theory is adopted to evaluate the aerodynamic pressure. Hamilton's principle with the assumed mode method is used to develop the dynamical model of the structural systems. By using the standard eigenvalue methodology, the solutions for the complex eigenvalue problem are obtained. A negative velocity feedback control strategy is used to obtain active damping. The aeroelastic flutter bounds are calculated and the active aeroelastic flutter characteristics are analyzed. The impulse responses of the structural system are obtained by using the Houbolt numerical algorithm to study the active aeroelastic vibration control. The influences of the non-dimensional aerodynamic pressure on the active flutter control are analyzed. From the numerical results it is observed that the aeroelastic flutter characteristics of the supersonic beams can be significantly improved and that the aeroelastic vibration amplitudes can be remarkably reduced, especially at the flutter points, by using the piezoelectric actuator/sensor pairs which can provide an active damping. Within a certain value of the feedback control gain, with the increase of it, the flutter aerodynamic pressure (or flutter velocity) can be increased and the control results are also improved.
01 Dec 2011-Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems
TL;DR: In this paper, a MEMS piezoelectric energy harvester with a wide operating frequency range was proposed by incorporating a high-frequency PEC cantilever and a metal base as the top and bottom stoppers with a low frequency PEC.
Abstract: We propose a MEMS piezoelectric energy harvester with a wide operating frequency range by incorporating a high-frequency piezoelectric cantilever and a metal base as the top and bottom stoppers with a low-frequency piezoelectric cantilever. Frequency up-conversion of the piezoelectric energy harvester is realized when the low-frequency piezoelectric cantilever impacts and scrapes through the high-frequency piezoelectric cantilever. For an input acceleration of 0.6 g, with top and bottom stopper distances of 0.75 and 1.1 mm, respectively, the operating frequency ranges from 33 to 43 Hz. The output voltage and power up to 95 mV and 94 nW can be achieved. Experimental results indicate that the frequency up-conversion mechanism significantly improves the effective power.
TL;DR: In this paper, a control law for active structural vibration control using piezoelectric patches at elevated temperatures is derived and experimentally verified using augmented constitutive equations, which includes the temperature dependence of piezolectric stress coefficient (e31) and permittivity.
Abstract: A new scheme for active structural vibration control using piezoelectric patches at elevated temperatures is analytically derived and experimentally verified A control law is derived using augmented piezoelectric constitutive equations which include the temperature dependence of piezoelectric stress coefficient (e31) and permittivity Since the temperature dependence of 'e31' and '' is not analytically known, their experimental values measured at elevated temperatures are used Using augmented constitutive equations, a finite element model of a smart two-dimensional isotropic plate instrumented with a collocated piezoelectric sensor?actuator pair is derived A control law for active vibration control of the first mode of the smart cantilevered plate is derived using negative velocity feedback Active vibration control of the first mode of a smart cantilevered plate is experimentally achieved at elevated temperatures ranging from 25 to 75??C under two cases: (i)?using a control law which ignores the temperature dependence of 'e31' and '' and (ii)?using a control law which includes the temperature dependence of 'e31' and '' A comparison between these two control laws shows that: (i)?active vibration control (AVC) performance is not maintained at elevated temperatures using a control law which ignores the temperature dependence of 'e31' and '' and (ii)?AVC performance is maintained at elevated temperatures when we use a control law which includes the temperature dependence of 'e31' and ''
TL;DR: In this article, a new approach to analyze the response from a piezoelectric wafer in an impedance-based structural health monitoring (SHM) method is proposed.
TL;DR: In this paper, an array of devices that map the strain field on a flexible polyvinylidene difluoride (PVDF) film surface is demonstrated, which can be detected even in the presence of parasitic capacitance.
Abstract: Piezoelectric sensors are useful for a range of applications, but passive arrays suffer from crosstalk and signal attenuation, which have complicated the development of array-based polyvinylidene difluoride (PVDF) sensors. We have used organic field-effect transistors, which are compatible with the low Curie temperature of a flexible piezoelectric polymer, i.e., PVDF, to monolithically fabricate transimpedance amplifiers directly on the sensor surface and convert the piezoelectric charge signal into a current signal, which can be detected even in the presence of parasitic capacitance. The device couples the voltage generated by the PVDF film under strain into the gate of organic thin-film transistors using an arrangement that allows the full piezoelectric voltage to couple to the channel while also increasing charge-retention time. A bipolar detector is created using ultraviolet-ozone treatment to shift the threshold voltage and increase the current of the transistor under both compressive and tensile strain. An array of devices that maps the strain field on a PVDF film surface is demonstrated.
TL;DR: In this paper, the influence of viscoelastic material properties, as featured by fibre reinforced plastics, on the measurement of Lamb waves with the aid of surface-applied piezoelectric sensors is examined.
TL;DR: The results of the paper constitute a sound basis to the equations of the theory of classical plates with piezoelectric effects, and provide a trustworthy algorithm for computation of the stressed state in the three-dimensional problem.
TL;DR: In this article, the authors investigated the combined optimization of bi-material structural layout and actuation voltage distribution of structures with embedded in-plane piezoelectric actuators.
TL;DR: In this article, a finite element (FE) for shell structures including actuators and sensors is presented, which has an enriched description of the transverse kinematics in order to consistently retain the full 3D piezoelectric coupling.
Abstract: This study presents a novel finite element (FE) for shell structures including piezoelectric actuators and sensors. Based on a conventional 8-node shell formulation and the classical displacement-based variational formulation, the present element has an enriched description of the transverse kinematics in order to consistently retain the full three-dimensional (3D) piezoelectric coupling. Furthermore, a layer-wise description of the electric degrees of freedom permits to account for embedded piezoelectric actuators and sensors. The robustness of the FE is enhanced by referring to an established technique that avoids transverse shear locking and membrane locking. Numerical results are given which validate the present implementation and highlight the efficiency and accuracy of the proposed formulation. Additionally, some new reference solutions for the static behavior of piezoelectric shells are provided by means of 3D FE computations with a commercial software.
TL;DR: In this paper, a three-nodded beam finite element is developed for the analysis of composite-laminated beams with distributed piezoelectric sensor/actuator layers.
Abstract: A three-nodded beam finite element is developed for the analysis of composite- laminated beams with distributed piezoelectric sensor/actuator layers. The mechanical part of the proposed element is based on the refined sinus model. This element does not require shear correction factor and ensures continuity conditions for displacements, transverse shear stresses as well as boundary conditions on the upper and lower surfaces of the beam. This conforming finite element is totally free of shear locking, and the number of mechanical unknowns is independent of the number of layers. For each piezoelectric layer, a high-order electrical potential field is considered. The virtual work principle leads to a derivation that could include dynamic analysis. However, in this study, only static problems have been considered. Comparison of numerical results obtained from this formulation with previous works shows that the present finite element is suitable for predicting fully coupled behaviors of both thick and thin smart-laminated beams under mechanical and electrical loadings.
TL;DR: In this paper, a piezoelectric transducer composed of a Molybdenum (Mo) top electrode, the Aluminum Nitride active layer and a Mo bottom electrode on a polymeric tape is reported.
TL;DR: In this paper, an active nonlinear acousto-ultrasonic piezoelectric sensor enabling low-cost and wide-frequency operational bandwidth is presented for the detection of delamination cracks in composites.
Abstract: A novel structural health monitoring (SHM) methodology, based on nonlinear wave modulation spectroscopy, is presented for the detection of delamination cracks in composites. The basic element is a novel active nonlinear acousto-ultrasonic piezoelectric sensor enabling low-cost and wide-frequency operational bandwidth. The active sensor configuration involves two piezoceramic wafer actuators, each one excited with a low- and high-frequency signal respectively, and a piezoceramic sensor, all permanently bonded on the tested structure. Experiments are conducted on two sets of composite strips containing delamination cracks of different sizes. Measured results illustrate first the efficiency of the nonlinear ultrasonics methodology to detect delamination cracks, as well as, the potential and benefits of the new active sensor. The sensitivity of the active sensor response to the crack size and the applied high-frequency carrier signals at the actuators, vary at various frequency and voltage levels indicating t...
01 Apr 2011-Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology
TL;DR: In this article, a modified Prandtl-Ishlinskii (PI) operator and its inverse is utilized for both identification and real time compensation of the hysteresis effect.
Abstract: Control of piezoelectric actuators is under the effects of hysteresis that could affect actuators micropositioning accuracy. In this paper a modified Prandtl–Ishlinskii (PI) operator and its inverse is utilized for both identification and real time compensation of the hysteresis effect. As a result, the actuator dynamic model would be transformed to the second order linear dynamic model. Considering the parametric uncertainties, PI estimation error and probably unmodeled dynamics, a variable structure controller coupled with adaptive perturbation estimation is proposed for trajectory tracking of the piezoelectric position. Considering the very noisy output of the actuator, a high-gain observer would estimate full states from the only measurable position trajectory. The stability of the controller in the presence of the estimated state is demonstrated with the Lyapunov criterion. Comparing to the widely used proportional–integral controller, the experimental results depicts that the proposed approach is greatly achieved in precisely tracking of multiple frequency trajectories.
TL;DR: In this paper, a brand new cement-based piezoelectric composite sensor was introduced with improved performance, particularly concerning its acoustic emission (AE) signals detection capacity in the high frequency domain.
Abstract: Damage process monitoring of concrete structures using acoustic emission (AE) technology has been drawn more and more attention due to its powerful capability. In this paper, a brand new cement-based piezoelectric composite sensor was introduced with improved performance, particularly concerning its AE signals detection capacity in the high frequency domain. Such sensors were embedded into the foundation of reinforced concrete (RC) frames during construction, and appointed to monitor concrete damage due to shake table excitation. A standard ground motion record of 1999 Taiwan earthquake with 840 gal and 1300 gal peak ground accelerations were employed in the tests as the excitation inputs. The signals detected by the sensors were stored and analyzed by commercial available data acquisition devices. Advanced stochastic signal analysis methods were adopted to effectively interpret the frequency domain components and identify the useful information representing the damage processes of the RC frames. The results were compared with the eye observations of structural damage and corresponding cyclic loading tests results. It is shown that the health monitoring method using cement-based piezoelectric composite sensors and advanced stochastic signal analysis are capable of detecting and evaluating the damage process of RC frames due to seismic loading. An effective damage indicator of the RC frames is possible to be evaluated from extracted AE information.
TL;DR: In this article, a configuration of piezoelectric transducers was proposed for damage detection and localization in an equilateral triangle that has a 2×2 transducer array in each vertex and a special algorithm was implemented to process these signals and extract features related to damage.
TL;DR: In this paper, the authors surveyed ReCa 4 O(BO 3 ) 3 (Re: rare earth element; abbreviated as ReCOB) piezoelectric crystals for their potential use in high temperature sensing applications.
TL;DR: In this article, a resonant sensor is built using cantilever structure with piezoelectric excitation, sensing and microcontroller based closed loop electronics to measure the unknown mass by measuring the shift in resonance frequency.