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Study of parasitic resistance effects in nanowire and nanoribbon biosensors.

Zeimpekis I, Sun K, Hu C, Thomas O, de Planque MR, Chong HM, Morgan H, Ashburn P - Nanoscale Res Lett (2015)

Bottom Line: Measurements of pH with polysilicon nanoribbon biosensors are used to demonstrate a reduction in sensitivity as the sensor length is reduced.These results are interpreted using a simple empirical model, which is also used to demonstrate how the sensitivity degradation can be alleviated by a suitable choice of sensor window length.Furthermore, a differential sensor design is proposed that eliminates the detrimental effects of parasitic resistance.

View Article: PubMed Central - PubMed

Affiliation: Zepler Institute, School of Electronics & Computer Science, University of Southampton, Southampton, SO17 1BJ UK.

ABSTRACT
In this work, we investigate sensor design approaches for eliminating the effects of parasitic resistance in nanowire and nanoribbon biosensors. Measurements of pH with polysilicon nanoribbon biosensors are used to demonstrate a reduction in sensitivity as the sensor length is reduced. The sensitivity (normalised conductance change) is reduced from 11% to 5.5% for a pH change from 9 to 3 as the sensing window length is reduced from 51 to 11 μm. These results are interpreted using a simple empirical model, which is also used to demonstrate how the sensitivity degradation can be alleviated by a suitable choice of sensor window length. Furthermore, a differential sensor design is proposed that eliminates the detrimental effects of parasitic resistance. Measurements on the differential sensor give a sensitivity of 15%, which is in good agreement with the predicted maximum sensitivity obtained from modeling.

No MeSH data available.


Schematic cross-section and plan views of the polysilicon nanoribbon biosensor.
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Fig2: Schematic cross-section and plan views of the polysilicon nanoribbon biosensor.

Mentions: To study the relationship between sensitivity and sensor dimensions, a simple model is presented in Figure 2. The model includes three sections; the wet section (Rsense) where the sensor is exposed to liquid and two dry sections (Rpar) where it is protected from liquid by SU8. All sections contribute to the overall resistance (R), which can be measured directly from electrical measurements. The dry section includes the contact resistance from the TiN/Si contacts (Rc) and the parasitic resistance of the nanoribbon region covered by SU8 (Rrbd).Figure 2


Study of parasitic resistance effects in nanowire and nanoribbon biosensors.

Zeimpekis I, Sun K, Hu C, Thomas O, de Planque MR, Chong HM, Morgan H, Ashburn P - Nanoscale Res Lett (2015)

Schematic cross-section and plan views of the polysilicon nanoribbon biosensor.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385057&req=5

Fig2: Schematic cross-section and plan views of the polysilicon nanoribbon biosensor.
Mentions: To study the relationship between sensitivity and sensor dimensions, a simple model is presented in Figure 2. The model includes three sections; the wet section (Rsense) where the sensor is exposed to liquid and two dry sections (Rpar) where it is protected from liquid by SU8. All sections contribute to the overall resistance (R), which can be measured directly from electrical measurements. The dry section includes the contact resistance from the TiN/Si contacts (Rc) and the parasitic resistance of the nanoribbon region covered by SU8 (Rrbd).Figure 2

Bottom Line: Measurements of pH with polysilicon nanoribbon biosensors are used to demonstrate a reduction in sensitivity as the sensor length is reduced.These results are interpreted using a simple empirical model, which is also used to demonstrate how the sensitivity degradation can be alleviated by a suitable choice of sensor window length.Furthermore, a differential sensor design is proposed that eliminates the detrimental effects of parasitic resistance.

View Article: PubMed Central - PubMed

Affiliation: Zepler Institute, School of Electronics & Computer Science, University of Southampton, Southampton, SO17 1BJ UK.

ABSTRACT
In this work, we investigate sensor design approaches for eliminating the effects of parasitic resistance in nanowire and nanoribbon biosensors. Measurements of pH with polysilicon nanoribbon biosensors are used to demonstrate a reduction in sensitivity as the sensor length is reduced. The sensitivity (normalised conductance change) is reduced from 11% to 5.5% for a pH change from 9 to 3 as the sensing window length is reduced from 51 to 11 μm. These results are interpreted using a simple empirical model, which is also used to demonstrate how the sensitivity degradation can be alleviated by a suitable choice of sensor window length. Furthermore, a differential sensor design is proposed that eliminates the detrimental effects of parasitic resistance. Measurements on the differential sensor give a sensitivity of 15%, which is in good agreement with the predicted maximum sensitivity obtained from modeling.

No MeSH data available.