Preparation of Piezoresistive Microcantilever for Biosensor Application (original) (raw)
Related papers
Fabrication of piezoresistive microcantilever using surface micromachining technique for biosensors
2005
A microcantilever-based biosensor with piezoresistor has been fabricated using surface micromachining technique, which is cost effective and simplifies a fabrication procedure. In order to evaluate the characteristics of the cantilever, the cystamine terminated with thiol was covalently immobilized on the gold-coated side of the cantilever and glutaraldehyde that would be bonded with amine group in the cystamine was injected subsequently. This process was characterized by measuring the deflection of the cantilever in real time monitoring. Using a piezoresistive read-out and a well-known optical beam deflection method as well, the measurement of deflection was carried out. The sensitivity of piezoresistive method is good enough compared with that of optical beam deflection method.
Sains Malaysiana, 2011
In principle, adsorption of biological molecules on a functionalized surface of a microfabricated cantilever will cause a surface stress and consequently the cantilever bending. In this work, four different type of polysilicon-based piezoresistive microcantilever sensors were designed to increase the sensitivity of the microcantilevers sensor because the forces involved is very small. The design and optimization was performed by using finite element analysis to maximize the relative resistance changes of the piezoresistors as a function of the cantilever vertical displacements. The resistivity of the piezoresistivity microcantilevers was analyzed before and after dicing process. The maximum resistance changes were systematically investigated by varying the piezoresistor length. The results show that although the thickness of piezoresistor was the same at 0.5 μm the resistance value was varied.
Design and Analysis of Microcantilevers for Biosensing Applications
Journal of the Association for Laboratory Automation, 2003
W e have analyzed the detection of microcantilevers utilized in biosensing chips. First, the primary deflection due to the chemical reaction between the analyte molecules and the receptor coating, which produces surface stresses on the receptor side is analyzed. Oscillating flow conditions, which are the main source of turbulence in cantilever based biosensing chips, are found to produce substantial deflections in the microcantilever at relatively large frequency of turbulence. Then mechanical design and optimization of piezoresistive cantilevers for biosensing applications is studied. Models are described for predicting the static behavior of cantilevers with elastic and piezoresistive layers. Chemo-mechanical binding forces have been analyzed to understand issues of saturation over the cantilever surface. Furthermore, the introduction of stress concentration regions during cantilever fabrication has been discussed which greatly enhances the detection sensitivity through increased surface stress, and novel microcantilever assemblies are presented for the first time that can increase the deflection due to chemical reaction. Finally an experiment was made to demonstrate the shift of resonant frequency of cantilever used as biosensor. The relation between resonant frequency shift and the surface stress was analyzed.
Microcantilever based Biosensor for Disease Detection Applications
Journal of Medical and Bioengineering, 2015
The fast development of micro-electromechanical system (MEMS) technology has brought many great ideas in the field of biomedical applications. A biosensor is a chemical sensing device in which a biologically derived recognition analyte coupled to a transducer to allow the quantitative development of biochemical parameter. A biosensor consists of a bio-element and a sensor-element. The bio-element may be an enzyme, antibody, living cells, tissue, etc., and the sensing element may be electric current, electric potential, and so on and specificity of analyte is the important concept in biosensor. In this paper we review the principle of microcantilever, biosensing mechanism and applications of microcantilevers for bio detection for early detection of diseases accurately. Biosensors can have a variety of biomedical, industry, and military applications. The main advantages of MEMS based sensors are specificity, portability, simplicity, high sensitivity, potential ability for real-time and on-site analysis coupled with the high speed and low cost.
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.
Effects of design parameters on sensitivity of microcantilever biosensors
IEEE/ICME International Conference on Complex Medical Engineering, 2010
Microcantilever biosensors produce cantilever bending due to differential surface stress between upper and lower surfaces of the cantilever. The bending is associated with concentration of ligands and adsorbed ligand-receptor intermolecular forces. Sample volume sizes in clinical diagnostic applications are usually very minute requiring a highly sensitive microcantilever for disease detection. This paper investigates a number of parameters that influence the sensitivity of microcantilever biosensors. The parameters include length, thickness, shape, and material of the cantilever beam. Biosensors of varying parameters are modeled and simulated. The results show that increasing the length of the cantilever beam enhances its sensitivity. However, increasing the thickness of the cantilever beam reduces its sensitivity. In static analysis, the shape of the cantilever beam does not notably impact upon its sensitivity. Also, using materials with lower Young's modulus improves the sensitivity.
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.
Biosensors and Bioelectronics, 2005
We report an electro-mechanical biosensor for electrical detection of proteins with disease markers using self-sensing piezoresistive microcantilevers. Electrical detection, via surface stress changes, of antigen-antibody (Ag-Ab) specific binding was accomplished through a direct nano-mechanical response of micro-fabricated self-sensing micro-cantilevers. A piezoresistive sensor measures the film resistance variation with respect to surface stress caused by biomolecules specific binding. When specific binding occurred on a functionalized Au surface, surface stress was induced throughout the cantilever, resulting in cantilever bending and resistance change of the piezoresistive layer. The cantilever biosensors were used for the detection of prostate specific antigen (PSA) and C-reactive proteins (CRP), which are a specific marker of prostate cancer and cardiac disease. From the above experiment, it was revealed that the sensor output voltage was proportional to the injected antigen concentration (without antigen, 10 ng/ml, 100 ng/ml, 1 g/ml). PSA and CRP antibodies were found to be very specific for their antigens, respectively. This indicated that the self-sensing micro-cantilever approach is beneficial for detecting disease markers, and our piezoresistive micro-cantilever sensor system is applicable to miniaturized biosensor systems.