Мікро- та наносенсори / L3
.1.pdf
Principles of Electronic Nanobiosensors
Unit 3: Sensitivity
Lecture 3.1: Nanobiosensors:
Sensitivity and Types of Biosensors
By Muhammad A. Alam
Professor of Electrical and Computer Engineering Purdue University
alam@purdue.edu
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Outline
• Background and introduction
– Geometry of diffusion defines the detection limits
– Sensor must be sensitive to the analyte
• Three types of nanobiosensors
– Tags vs. transducers
• Potentiometric sensor
– Basic operation
– Puzzle regarding analyte density
• Conclusions
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importance of sensi8vity
If the sensor does not notice the analyte, it does not exist!
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Part 1: Geometry of di usion
aM |
fM |
pM |
nM |
M |
Regardless the sensors, the diffusion limits must be
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Sensi8vity |
by detec8on |
ts response time
Capture |
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3−DF |
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Limits of |
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Diffusion geometry |
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detection |
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Minimum # molecules |
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Types sensors: tags vs. transducer
Ø Charge Ø Mass
Ø Electron affinity
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Ref
Electrode
of
Virus/bacteria Protein/DNA |
PCR |
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pH-meter |
Genome |
(potentiometric) amperometric) |
sequencer |
Vacuum tube |
MOS |
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Important as pH-meter and genome sequencers
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I = q n υ× A×
υ = µE = µ VLD
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of a
ID,before |
analyte |
ID ,after |
S ≡ |
ID,after − ID,before |
≡ |
ID |
ID,before |
ID |
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