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High S/N ratio slotted step piezoresistive microcantilever designs for biosensors.

Ansari MZ, Cho C - Sensors (Basel) (2013)

Bottom Line: The cantilever step length and piezoresistor length is varied along with the operating voltage to characterise the surface stress sensitivity and thermal drifting sensitivity of the cantilevers when used as immunosensor.The numerical analysis is performed using ANSYS Multiphysics.Results show the surface stress sensitivity and the S/N ratio of the slotted step cantilevers is improved by more than 32% and 22%, respectively, over its monolithic counterparts.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Inha University, 253 Yonghyun-dong, Nam-Ku, Incheon 402-751, Korea. ansari.zahid@hotmail.com

ABSTRACT
This study proposes new microcantilever designs in slotted step configuration to improve the S/N ratio of surface stress-based sensors used in physical, chemical, biochemical and biosensor applications. The cantilevers are made of silicon dioxide with a u-shaped silicon piezoresistor in p-doped. The cantilever step length and piezoresistor length is varied along with the operating voltage to characterise the surface stress sensitivity and thermal drifting sensitivity of the cantilevers when used as immunosensor. The numerical analysis is performed using ANSYS Multiphysics. Results show the surface stress sensitivity and the S/N ratio of the slotted step cantilevers is improved by more than 32% and 22%, respectively, over its monolithic counterparts.

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Schematic of slotted (top) and monolithic (below) step microcantilever designs with u-shaped piezoresistor.
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f1-sensors-13-04088: Schematic of slotted (top) and monolithic (below) step microcantilever designs with u-shaped piezoresistor.

Mentions: In case of piezoresistive microcantilever sensors, the adsorbate-induced surface stress change on the functionalised surface of the cantilever induces stress in its piezoresistor and changes its electrical resistance. The measurement of the change in resistance provides the information about the type and concentration of the adsorbing analyte. Figure 1 shows the schematic diagrams of the step piezoresistive microcantilever in slotted and monolithic configurations. The fixed-end thickness is 1 µm and the free-end thickness is 0.5 µm. In the slotted designs, a rectangular hole of length 50 µm and width 60 µm is introduced abutting the fixed end. The cantilevers are made of silicon dioxide with a u-shape silicon piezoresistor with p-type dopant. The width of piezoresistor is constant at 20 µm. A thin film of gold is also deposited on the top surface to help monolayer assembly of analyte molecules. The analyte-receptor interactions are assumed occur at the top surface and produce tensile surface stress.


High S/N ratio slotted step piezoresistive microcantilever designs for biosensors.

Ansari MZ, Cho C - Sensors (Basel) (2013)

Schematic of slotted (top) and monolithic (below) step microcantilever designs with u-shaped piezoresistor.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3673072&req=5

f1-sensors-13-04088: Schematic of slotted (top) and monolithic (below) step microcantilever designs with u-shaped piezoresistor.
Mentions: In case of piezoresistive microcantilever sensors, the adsorbate-induced surface stress change on the functionalised surface of the cantilever induces stress in its piezoresistor and changes its electrical resistance. The measurement of the change in resistance provides the information about the type and concentration of the adsorbing analyte. Figure 1 shows the schematic diagrams of the step piezoresistive microcantilever in slotted and monolithic configurations. The fixed-end thickness is 1 µm and the free-end thickness is 0.5 µm. In the slotted designs, a rectangular hole of length 50 µm and width 60 µm is introduced abutting the fixed end. The cantilevers are made of silicon dioxide with a u-shape silicon piezoresistor with p-type dopant. The width of piezoresistor is constant at 20 µm. A thin film of gold is also deposited on the top surface to help monolayer assembly of analyte molecules. The analyte-receptor interactions are assumed occur at the top surface and produce tensile surface stress.

Bottom Line: The cantilever step length and piezoresistor length is varied along with the operating voltage to characterise the surface stress sensitivity and thermal drifting sensitivity of the cantilevers when used as immunosensor.The numerical analysis is performed using ANSYS Multiphysics.Results show the surface stress sensitivity and the S/N ratio of the slotted step cantilevers is improved by more than 32% and 22%, respectively, over its monolithic counterparts.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Inha University, 253 Yonghyun-dong, Nam-Ku, Incheon 402-751, Korea. ansari.zahid@hotmail.com

ABSTRACT
This study proposes new microcantilever designs in slotted step configuration to improve the S/N ratio of surface stress-based sensors used in physical, chemical, biochemical and biosensor applications. The cantilevers are made of silicon dioxide with a u-shaped silicon piezoresistor in p-doped. The cantilever step length and piezoresistor length is varied along with the operating voltage to characterise the surface stress sensitivity and thermal drifting sensitivity of the cantilevers when used as immunosensor. The numerical analysis is performed using ANSYS Multiphysics. Results show the surface stress sensitivity and the S/N ratio of the slotted step cantilevers is improved by more than 32% and 22%, respectively, over its monolithic counterparts.

Show MeSH