Midterm Report

Professor: Cheng-Hsien, LiuStudent: Yi-Jou, Lin Date: 2009/11/03

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. Li21Micromachines Centre, Nanyang Technological University, Singapore

2School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore

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IntroductionPiezoelectric Biosensors

- Micro-machined catilever - Quartz-Crystal Microbalance System (QCMS) - Micro-diaphragm

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IntroductionPiezoelectric Biosensors

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

Micro-machined catilever

Quartz-Crystal Microbalance System (QCMS)

Micro-diaphram

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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IntroductionPiezoelectric Biosensor

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

Micro-machined catilever

Quartz-Crystal Microbalance System (QCMS)

Micro-diaphram

Fig.2 Libra DNA-sensor and piezoelectric quartz.

Fig. 3. Scheme of DNA immobilization and hybridization on golden quartz.

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IntroductionPiezoelectric Biosensors

High sensitivity High limit of detection

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. Li21Micromachines Centre, Nanyang Technological University, Singapore

2School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore

generate stronger output signal

detect the minimum concentration of the analyte

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IntroductionPiezoelectric Biosensors

How to improve the sensitivity? (1) Gold-nanoparticles (2) Carbon nanotubes (CNTs)

Micro-machined catilever

Quartz-Crystal Microbalance System (QCMS)

Micro-diaphram

A HIGH SENSITIVITY CARBON NANOTUBES ENHANCED PZT DIAPHRAM-BASEDIMMUNOSENSOR ARRAYT. 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

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

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 6/12

Fabrication of piezoelectricdiaphragm-based biosensor array

SOI wafer

PZT=Pb(Zr0.52Ti0.48)O3

TiO2/Pt

Si3N4

Ti/Pt

deposit

Deposit

Patterned &etching

Sputtered & patterned

DRIETop electrode

bottom electrode

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Fabrication of piezoelectricdiaphragm-based biosensor array

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.

Fig 5. Sketched immobilization processes for the CNT enhanced PZT biosensor.

-goat IgG

Anti-goat IgG

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Results

FSEM & AFM images

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.

58-66 nm82-105 nm

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Results

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.

High sensitivity

High limit of detection

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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 cantilever-based 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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