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Size matters: problems and advantages associated with highly miniaturized sensors.

Dahlin AB - Sensors (Basel) (2012)

Bottom Line: Still, all issues discussed are generic in the sense that the conclusions apply to practically all types of surface sensitive techniques.Instead, it is suggested that sensing on the microscale often offers a good compromise between utilizing some possible advantages of miniaturization while avoiding the complications.This means that ensemble measurements on multiple nanoscale sensors are preferable instead of utilizing a single transducer entity.

View Article: PubMed Central - PubMed

Affiliation: Division of Bionanophotonics, Department of Applied Physics, Chalmers University of Technology, Göteborg, Sweden. adahlin@chalmers.se

ABSTRACT
There is no doubt that the recent advances in nanotechnology have made it possible to realize a great variety of new sensors with signal transduction mechanisms utilizing physical phenomena at the nanoscale. Some examples are conductivity measurements in nanowires, deflection of cantilevers and spectroscopy of plasmonic nanoparticles. The fact that these techniques are based on the special properties of nanostructural entities provides for extreme sensor miniaturization since a single structural unit often can be used as transducer. This review discusses the advantages and problems with such small sensors, with focus on biosensing applications and label-free real-time analysis of liquid samples. Many aspects of sensor design are considered, such as thermodynamic and diffusion aspects on binding kinetics as well as multiplexing and noise issues. Still, all issues discussed are generic in the sense that the conclusions apply to practically all types of surface sensitive techniques. As a counterweight to the current research trend, it is argued that in many real world applications, better performance is achieved if the active sensor is larger than that in typical nanosensors. Although there are certain specific sensing applications where nanoscale transducers are necessary, it is argued herein that this represents a relatively rare situation. Instead, it is suggested that sensing on the microscale often offers a good compromise between utilizing some possible advantages of miniaturization while avoiding the complications. This means that ensemble measurements on multiple nanoscale sensors are preferable instead of utilizing a single transducer entity.

No MeSH data available.


First report of label-free biomolecule detection from serum with single molecule resolution using an optical microcavity (whispering gallery mode) resonator. The resonator shape and size is illustrated in (A). Examples of binding curves with discretized signal steps is shown in (B) when interleukin binds to the sensor surface. Reproduced with permission from Reference [35] (Copyright 2007 American Association for the Advancement of Science).
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f4-sensors-12-03018: First report of label-free biomolecule detection from serum with single molecule resolution using an optical microcavity (whispering gallery mode) resonator. The resonator shape and size is illustrated in (A). Examples of binding curves with discretized signal steps is shown in (B) when interleukin binds to the sensor surface. Reproduced with permission from Reference [35] (Copyright 2007 American Association for the Advancement of Science).

Mentions: Resolving single molecule binding events appears to be a dream for most researchers working with sensor development. When the sensor signal is determined by Γ, reducing A is the most obvious way to get a fewer number of molecules corresponding to the same signal. The smallest sensors to date are probably single plasmonic nanoparticles [32], which seem to be just at the limit of resolving single biomolecular binding events [33,34]. It is clear that as long as A is ∼1 μm2 or higher, single molecule resolution cannot be realized because the detection limit in Γ is always so high that the signal to noise ratio is lower than the number of bound molecules. It thus appears reasonable to claim that nanosensors are required for resolving single molecules. In this context it is interesting to note that detection of single molecule binding events were first reported with a relatively large (microscale) optical sensor (Figure 4) utilizing so called whispering gallery modes [35]. Since then the heating mechanism suggested to be responsible for the large signal per molecule has been questioned [36], but development of the sensor continues [6]. Although it represents an impressive engineering achievement worthy of attention, it is worth to ask the question what the single molecule resolution feature contributes with in terms of sensor efficiency.


Size matters: problems and advantages associated with highly miniaturized sensors.

Dahlin AB - Sensors (Basel) (2012)

First report of label-free biomolecule detection from serum with single molecule resolution using an optical microcavity (whispering gallery mode) resonator. The resonator shape and size is illustrated in (A). Examples of binding curves with discretized signal steps is shown in (B) when interleukin binds to the sensor surface. Reproduced with permission from Reference [35] (Copyright 2007 American Association for the Advancement of Science).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376590&req=5

f4-sensors-12-03018: First report of label-free biomolecule detection from serum with single molecule resolution using an optical microcavity (whispering gallery mode) resonator. The resonator shape and size is illustrated in (A). Examples of binding curves with discretized signal steps is shown in (B) when interleukin binds to the sensor surface. Reproduced with permission from Reference [35] (Copyright 2007 American Association for the Advancement of Science).
Mentions: Resolving single molecule binding events appears to be a dream for most researchers working with sensor development. When the sensor signal is determined by Γ, reducing A is the most obvious way to get a fewer number of molecules corresponding to the same signal. The smallest sensors to date are probably single plasmonic nanoparticles [32], which seem to be just at the limit of resolving single biomolecular binding events [33,34]. It is clear that as long as A is ∼1 μm2 or higher, single molecule resolution cannot be realized because the detection limit in Γ is always so high that the signal to noise ratio is lower than the number of bound molecules. It thus appears reasonable to claim that nanosensors are required for resolving single molecules. In this context it is interesting to note that detection of single molecule binding events were first reported with a relatively large (microscale) optical sensor (Figure 4) utilizing so called whispering gallery modes [35]. Since then the heating mechanism suggested to be responsible for the large signal per molecule has been questioned [36], but development of the sensor continues [6]. Although it represents an impressive engineering achievement worthy of attention, it is worth to ask the question what the single molecule resolution feature contributes with in terms of sensor efficiency.

Bottom Line: Still, all issues discussed are generic in the sense that the conclusions apply to practically all types of surface sensitive techniques.Instead, it is suggested that sensing on the microscale often offers a good compromise between utilizing some possible advantages of miniaturization while avoiding the complications.This means that ensemble measurements on multiple nanoscale sensors are preferable instead of utilizing a single transducer entity.

View Article: PubMed Central - PubMed

Affiliation: Division of Bionanophotonics, Department of Applied Physics, Chalmers University of Technology, Göteborg, Sweden. adahlin@chalmers.se

ABSTRACT
There is no doubt that the recent advances in nanotechnology have made it possible to realize a great variety of new sensors with signal transduction mechanisms utilizing physical phenomena at the nanoscale. Some examples are conductivity measurements in nanowires, deflection of cantilevers and spectroscopy of plasmonic nanoparticles. The fact that these techniques are based on the special properties of nanostructural entities provides for extreme sensor miniaturization since a single structural unit often can be used as transducer. This review discusses the advantages and problems with such small sensors, with focus on biosensing applications and label-free real-time analysis of liquid samples. Many aspects of sensor design are considered, such as thermodynamic and diffusion aspects on binding kinetics as well as multiplexing and noise issues. Still, all issues discussed are generic in the sense that the conclusions apply to practically all types of surface sensitive techniques. As a counterweight to the current research trend, it is argued that in many real world applications, better performance is achieved if the active sensor is larger than that in typical nanosensors. Although there are certain specific sensing applications where nanoscale transducers are necessary, it is argued herein that this represents a relatively rare situation. Instead, it is suggested that sensing on the microscale often offers a good compromise between utilizing some possible advantages of miniaturization while avoiding the complications. This means that ensemble measurements on multiple nanoscale sensors are preferable instead of utilizing a single transducer entity.

No MeSH data available.