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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.

Show MeSH
The longitudinal thermal stress distribution (MPa) in different (l, lp) microcantilever designs for bias voltage 5 V.
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f4-sensors-13-04088: The longitudinal thermal stress distribution (MPa) in different (l, lp) microcantilever designs for bias voltage 5 V.

Mentions: Figure 4 shows the self-heating-induced longitudinal thermal stress (σl,T) distribution in the piezoresistor of slotted and monolithic cantilevers subjected to a bias voltage of 5 V. The top edge is the fixed end of the cantilever where the bias voltages are applied. It is interesting to note that the maximum thermal stress in all the cantilevers is nearly same in magnitude. In other words, the change in the piezoresistor or the step length has negligible effect on the maximum thermal stress in the cantilevers. This is in contrast to the mechanical stress values shown in Figure 2 wherein the stress values for (100, 50) and (150, 50) designs are the highest for the two step lengths. Another observation in Figure 4 is that the values of thermal stress are much larger than mechanical stress shown in Figure 3. This means the resistance change produced by the self-heating effect in form of bimetallic bending will be much larger than that by the surface stress-induced bending (i.e., signal) and therefore will produce large noise in the measurements.


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

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

The longitudinal thermal stress distribution (MPa) in different (l, lp) microcantilever designs for bias voltage 5 V.
© Copyright Policy
Related In: Results  -  Collection

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

f4-sensors-13-04088: The longitudinal thermal stress distribution (MPa) in different (l, lp) microcantilever designs for bias voltage 5 V.
Mentions: Figure 4 shows the self-heating-induced longitudinal thermal stress (σl,T) distribution in the piezoresistor of slotted and monolithic cantilevers subjected to a bias voltage of 5 V. The top edge is the fixed end of the cantilever where the bias voltages are applied. It is interesting to note that the maximum thermal stress in all the cantilevers is nearly same in magnitude. In other words, the change in the piezoresistor or the step length has negligible effect on the maximum thermal stress in the cantilevers. This is in contrast to the mechanical stress values shown in Figure 2 wherein the stress values for (100, 50) and (150, 50) designs are the highest for the two step lengths. Another observation in Figure 4 is that the values of thermal stress are much larger than mechanical stress shown in Figure 3. This means the resistance change produced by the self-heating effect in form of bimetallic bending will be much larger than that by the surface stress-induced bending (i.e., signal) and therefore will produce large noise in the measurements.

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