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A HIGH SENSITIVITY CARBON NANOTUBES ENHANCED PZT
DIAPHRAM-BASED IMMUNOSENSOR ARRAY
T. Xu1, J.M. Miao1*, Z.H. Wang1, Y.S. Liu2 and C.M. Li2
1Micromachines Centre, Nanyang Technological University, Singapore
2School of Chemical and Biomedical Engineering, Nanyang Technological University,
Singapore
Professor: Cheng-Hsien, Liu
Student: Yi-Jou, Lin
Date: 2009/11/03
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Introduction
Piezoelectric Biosensors
- Micro-machined catilever
- Quartz-Crystal Microbalance System (QCMS)
- Micro-diaphragm
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Introduction
Piezoelectric Biosensors
Micro-machined
catilever
Quartz-Crystal Microbalance
System (QCMS)
Micro-diaphram
 Transduce different phenomena,
such as changes of mass,
temperature, heat, or stress, into
bending or a change in resonant
frequency
 High sensitivity
 Label-free detection
 Low quality merit factor
 Fragility of the devices
Fig 1. Scheme of the cantilever bending due
to a biomolecular interaction between an
immobilized receptor and its target. Only the
specific recognition causes a change on the
surface stress driving to the bending of the
cantilever.
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Introduction
Piezoelectric Biosensor
Micro-machined
catilever
Quartz-Crystal Microbalance
System (QCMS)
Micro-diaphram
 based on quartz crystal resonators,
and measured by a resonance
frequency decrease, as a result of
the superficial mass increase
Good frequency stability and
reproducibility
Unable to full fill the requirements as
the solid quartz crystal lacks of
integration
Fig.
3. Scheme
of DNA immobilization
Fig.2
Libra DNA-sensor
and
and
hybridization
on golden quartz.
piezoelectric
quartz.
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Introduction
Piezoelectric Biosensors
Micro-machined
catilever
Quartz-Crystal Microbalance
System (QCMS)
Micro-diaphram
A HIGH SENSITIVITY CARBON NANOTUBES ENHANCED PZT
DIAPHRAM-BASED IMMUNOSENSOR ARRAY
T. Xu1, J.M. Miao1*, Z.H. Wang1, Y.S. Liu2 and C.M. Li2
1Micromachines Centre, Nanyang Technological University, Singapore
2School of Chemical and Biomedical Engineering, Nanyang Technological University,
Singapore
High sensitivity
generate stronger output signal
High limit of detection
detect the minimum concentration of the analyte
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Introduction
Piezoelectric Biosensors
Micro-machined
catilever
A HIGH SENSITIVITY CARBON NANOTUBES ENHANCED
PZT DIAPHRAM-BASEDIMMUNOSENSOR ARRAY
T. Xu1, J.M. Miao1*, Z.H. Wang1, Y.S. Liu2 and C.M. Li2
1Micromachines Centre, Nanyang Technological University,
Singapore
2School of Chemical and Biomedical Engineering, Nanyang
Technological University, Singapore
Quartz-Crystal Microbalance
System (QCMS)
Micro-diaphram
 How to improve the sensitivity?
(1) Gold-nanoparticles
 Provide a 3D platform
 The high density and weight
of the gold might deposit and
cause peizoelectric diaphragm
deformation
 reliability problems during the
immobilization process
(2) Carbon nanotubes (CNTs)
 Extremely high surface area, 400
m2/g theoretically
 Enhance the electrochemical
reactivity of some molecules
 Useful for label-free
electrochemical detection
 Deposit on the electrodes with
applied voltage
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Fabrication of piezoelectric
diaphragm-based biosensor array
SOI wafer
PZT=
Pb(Zr0.52Ti0.48)O3
deposit
Sputtered &
patterned
Deposit
TiO2/Pt
DRIE
Top electrode
bottom electrode
Si3N4
Patterned
&etching
Ti/Pt
7/12
Fabrication of piezoelectric
diaphragm-based biosensor array
-goat IgG
Anti-goat IgG
Fig 5. Sketched immobilization processes for the CNT
enhanced PZT biosensor.
Fig. 4. Images of the fabricated biosensor array. (a)
Top view of an optical image of the device.
(b)Enlarged optical image of the active PZT
diaphragm. (c) SEM image of the reaction chamber
on the backside of the diaphragm.
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Results
 FSEM & AFM images
82-105 nm
58-66 nm
Fig 6. FESEM (a, b) and AFM (c, d) micrographs of CNTs. (a) & (c) CNTs were
pretreated by SDS. (b) & (d) CNTs after absorbing goat IgGs.
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Results
High sensitivity
High limit of detection
Figure 4. Detailed frequency shift of the two-sensor array (a)without CNTs, (b) with CNTs
after each immobilization processes
Figure 5. Relationship between the frequency depression and
concentration of the added anti-goat IgG.
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References
 L.G. Carrascosa, M. Moreno, M. Alvarez, L. M.Lechuga, “Nanomechanical
biosensors: a new sensing tool”, Trend Anal. Chem., vol. 25, pp. 196-206, 2006.
 R. Raiteri, M. Grattarola, H. J. Butt, and P. Skladal, “Micromechanical cantileverbased biosensors”, Sens. Actuators B, vol. 79, pp. 115-126, 2001.
 N. Perrot, E. Antoine, and C. Compere, “In situ QCM DNA-biosensor probe
modification” Sens. Actuators B, vol. 120, pp. 329-337, 2006.
 Myriam Passamano , Monica Pighini, “QCM DNA-sensor for GMOs detection”,
Sens. Actuators B, vol. 118, pp. 177-181, 2006.
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Thank you for your attention!!
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