Modeling of Piezoresistive Cantilevers for Chemical Sensing (original) (raw)
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Simulation and design of piezoelectric microcantilever chemical sensors
2005
This paper presents an analytical modeling of a piezoelectric multi-layer cantilever used as a micro-electro-mechanical-system (MEMS) chemical sensor. Selectively coated microcantilevers have been developed for highly sensitive chemical sensor applications. The proposed piezoelectric chemical sensor consists of an array of multi-layer piezoelectric cantilevers with voltage output in the millivolt range that replaces the conventional laser-based position-sensitive detection systems. The sensing principle is based upon changes in the deflection induced by environmental factors in the medium where a microcantilever is immersed. Bending of the cantilever induces the potential difference on opposite sides of the piezoelectric layer providing an information signal about the detected chemicals. To obtain an application specific optimum design parameters and predict the cantilever performance ahead of actual fabrication, finite element analysis (FEM) simulations using CoventorWare (a MEMS design and simulation program) were performed. Analytical models of multi-layer cantilevers as well as simulation concept are described. Both mechanical and piezoelectric simulation results are carried out. The cantilever structures are analyzed and fabrication process steps are proposed.
Defence Science Journal, 2016
Micro-electro-mechanical systems (MEMS)-based cantilever platform have capability for the detection of chemical and biological agents. This paper reports about the finite element method (FEM) based design and simulations of MEMS-based piezoresistor cantilever platform to be used for detection of chemical and biological toxic agents. Bulk micromachining technique is adopted for the realisation of the device structure. MEMS piezoresistive biosensing platforms are having potential for a field-based label-free detection of various types of bio-molecules. Using the MEMMECH module of CoventorWare® simulations are performed on the designed model of the device and it is observed that principal stress is maximum along the length (among other dimensions of the micro-cantilever) and remains almost constant for 90 per cent of the length of the micro-cantilever. The dimensions of piezoresistor are optimised and the output voltage vs. stress analysis for various lengths of the piezoresistor is performed using the MEMPZR module of the CoventorWare®.
Journal of Physics D: Applied Physics, 2015
Microcantilever platforms with integrated piezoresistors have found versatile applications in the field of clinical analysis and diagnostics. Even though treatise encompasses numerous design details of the cantilever based biochemical sensors, a majority of them focus on the generic slender rectangular cantilever platform mainly due to its evolution from the atomic force microscope (AFM). The reported designs revolve around the aspects of dimensional optimization and variations with respect to the combination of materials for the composite structure. In this paper, a triangular cantilever platform is shown to have better performance metrics than the reported generic slender rectangular and the square cantilever platforms with integrated piezoresistors for biochemical sensing applications. The selection and optimization of the triangular cantilever platform is carried out in two stages. In the first stage, the preliminary selection of the cantilever shape is performed based on the initial design obtained by analytical formulae and numerical simulations. The second stage includes the geometrical optimization of the triangular cantilever platform and the integrated piezoresistor. The triangular cantilever platform shows a better performance in terms of the figure of merit (FoM), ψ Δ = R R f (/) 0 2 and the measurement bandwidth. The simulation results show that the magnitude of ψ of the triangular platform is 77.21% and 65.64% higher than that of the slender rectangular and the square cantilever platforms respectively. Moreover, the triangular platform exhibits a measurement bandwidth that is 70.91% and 2.04 times higher than that of the slender rectangular and square cantilever structures respectively. For a better understanding of the 2D nature of the stress generated on the cantilever platform due to the surface stress, its spatial profile has been extracted and depicted graphically. Finally, a set of design rules are provided for optimizing the triangular cantilever platform and piezoresistor dimensions in terms of the electrical sensitivity and the mechanical stability for biochemical sensing applications.
High sensitivity piezoresistive cantilever design and optimization for analyte-receptor binding
2003
Abstract The mechanical design and optimization of piezoresistive cantilevers for biosensing applications is studied using finite element analysis. The change of relative resistivity of piezoresistive microcantilevers is analyzed in the presence of the chemical reaction at the receptor surface under the condition of oscillating flow. Chemo-mechanical binding forces have been analyzed in order to understand issues of saturation over the cantilever surface.
Engineering Mechanics ..., 2024
The focus of this research project is to enhance cantilever beam designs for biosensing applications by including Stress Concentration Regions (SCRs). The stress distribution across several cantilever beam designs was determined by simulating them using COMSOL Multiphysics. The earliest designs were developed utilizing Polyvinylidene fluoride (PVDF) to showcase improved sensitivity for mechanical detection without the need for labels in biosensor applications. The analysis of cantilever beams involves the examination of their eigenfrequency and stationary behavior in the context of piezoelectric effect physics. An analysis is conducted on several cantilever beam structures to determine the most appropriate one. In this analysis, the various beams are exposed to an identical mechanical force, and their respective displacements, potential voltage, von Mises stress, and eigenfrequencies are examined.
The spring constant calibration of the piezoresistive cantilever based biosensor
2010
Piezoresistive microcantilevers are widely applied to measurements of low forces, masses and viscosity. After surface functionalization they might be used as a biochemical sensors being capable of the intermolecular force investigation. The problem is that such sensors change its mechanical properties in the environment they operate. Therefore there is a need for a high accuracy technique being capable of measuring of mechanical properties of functionalized cantilevers operating in the target environment. We suppose that such conditions meet the analysis of thermomechanical oscillation noise.
This paper considers the use of surface stress based sensors as bio chemical sensors. In principle, adsorption of bio chemical species on a functionalized surface of a microfabricated cantilever will cause surface stress and consequently the cantilever bends. Piezoresistive actuation of a micro cantilever induced by bio molecular binding such as DNA hybridization and antibody-antigen binding is an important principle. This paper presents design and simulation studies of gold coated Piezoresistive cantilever used as Micro Electro Mechanical System (MEMS) based biosensor for the detection of Low Density Lipoproteins (LDL). This paper uses Finite Element Method (FEM) to obtain the performance of piezoresistive microcantilever sensor by optimizing the geometrical dimensions of both cantilever and piezoresistor. A 200µm X 100µm X 1µm Silicon cantilever integrated with 0.3 µm thick Silicon piezoresistor, with 1µm of gold coating was used. The sensor performance was measured on the basis of displacement sensitivity and surface stress sensitivity. The sensor sensitivity was investigated by varying cantilever thickness as well as piezoresistor thickness and its width. Simulation results show that the cantilever sensitivity is good when cantilever, piezoresistor thickness and piezoresistor width are at minimum.
Optimised cantilever biosensor with piezoresistive read-out
Ultramicroscopy, 2003
We present a cantilever-based biochemical sensor with piezoresistive read-out which has been optimised for measuring surface stress. The resistors and the electrical wiring on the chip are encapsulated in low-pressure chemical vapor deposition (LPCVD) silicon nitride, so that the chip is well suited for operation in liquids. The wiring is titanium silicide which-in contrast to conventional metal wiring-is compatible with the high-temperature LPCVD coating process. r