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Consider the quality factor Q for one degree of freedom in terms of k

Consider the quality factor Q for one degree of freedom in terms of k

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Consider the quality factor Q for one degree of freedom in

terms of kinetic energy (KE) and potential energy (PE), in

total (KE+PE). For a resonator at any instant to the energy

dissipated in one cycle of vibration. When the quality factor

is much greater thon 1, the quality factor can be calculated

in terms of the resonator mass, damping and

stiffness/frequency. What are these expressions for the

quality factor? What are the consequences of a low quality

value, in which Q is not much greater than 1 anymore, for

a small mass detection with Nano resonators? What two

advantage does the suspended micro channel resonator

offer for working with micro resonator sensors when the

mass detected must be retained in a medium of fluid?

Solution

In general, mechanical biosensors capitalize on attributes

that scale advantageously as physical size is reduced.

First, nanoscale mechanical sensors provide exquisite

mass resolution — the minimum detectable added mass is

proportional to the total mass of the device.

Nanoelectromechanical systems (NEMS) have achieved

zeptogramscale mass resolution while operating in

vacuum, and nanogram resolution while operating in a fluid

environment1.

Second, the mechanical compliance of a device — its

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ability to be displaced or deformed — greatly increases

with uniform reduction of its dimensions.

Mechanical compliance converts an applied force into a

measurable displacement (and is the mechanical analogue

of gain in electronic circuits).

This enhanced force responsivity opens new opportunities

for measuring the miniscule forces that govern biological

interactions.

For example, nanomechanical sensors can resolve forces

of 10 pN, which is sensitive enough to detect the rupturing

of individual hydrogen bonds.

Third, small fluidic mechanical devices can exhibit fast

response times.

This allows biological processes in fluids to be observed

on the timescales of milliseconds or shorter over which

stochastic molecular interactions begin to evolve.

Mechanical biosensors can generally be delineated into

four broad categories based on the chemical interactions

between the sensor and the analyte:

(1) affinity-based assays where highly selective target

identification and capture is achieved by the employing

high specificity (that is, affinity) between the target and the

‘functionalization’ at the device surface.

Highly specific interactions can exist, for example,

between antigens and antibodies;

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Consider the quality factor Q for one degree of freedom in terms of kinetic energy (KE) and potential energy (PE), in total (KE+PE). For a resonator at any instant to the energy dissipated in one cycle of vibration. When the quality factor is much greater thon 1, the quality factor can be calculated in terms of the resonator mass, damping and stiffness/frequency. What are these expressions for the quality factor? What are the consequences of a low quality value, in which Q is not much greater than 1 anymor e, for a small mass detection with Nano resonators? What two advantage does the suspended micro channel resonator offer for working with micro resonator sensors when the mass detected must be retained in a medium of fluid? Solution In general, mechanical biosensors capitalize on attributes that scale advantageously as physical size is reduced. First, nanoscale mechanical sensors provide exquisite mass resolution — the minimum detectable added mass is proportional to the total mass of the device. Nanoelectromechanical systems (NEMS) have achieved zeptogramscale mass resolution while operating in vacuum, and nanogram resolution while operating in a fluid environment1. Second, t ...
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