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Journal of Zhejiang University SCIENCE C

ISSN 1869-1951(Print), 1869-196x(Online), Monthly

A micro-machined thin film electro-acoustic biosensor for detection of pesticide residuals

Abstract: Increasing awareness concerning food safety problems has been driving the search for simple and efficient biochemical analytical methods. In this paper, we develop a portable electro-acoustic biosensor based on a film bulk acoustic resonator for the detection of pesticide residues in agricultural products. A shear mode ZnO film bulk acoustic resonator with a micro-machining structure was fabricated as a mass-sensitive transducer for the real-time detection of antibody-antigen reactions in liquids. In order to obtain an ultra-low detection level, the artificial antigens were immobilized on the sensing surface of the resonator to employ a competitive format for the immunoassays. The competitive immunoreactions can be observed clearly through monitoring the frequency changes. The presence of pesticides was detected through the diminution of the frequency shift compared with the level without pesticides. The limit of detection for carbaryl (a widely used pesticide for vegetables and crops) is 2×10−10 M. The proposed device represents a potential alternative to the complex optical systems and electrochemical methods that are currently being used, and represents a significant opportunity in terms of simplicity of use and portability for on-site food safety testing.

Key words: Biosensors, Electro-acoustic resonator, Pesticide residues, Immunoreactions

Chinese Summary  <31> 基于薄膜电声谐振器的农药残留传感器

研究目的:过量农药残留是目前食品安全中的重要问题之一。现有的标准色谱、质谱方法和酶联免疫等生物传感器无法进行高灵敏的、普及化的、在线和迅速的农药残留检测。本文基于微机电系统技术,提出基于薄膜体声波电声谐振器(film bulk acoustic resonator, FBAR)的高灵敏生物传感器,并将其应用于农药残留检测。对该传感器的灵敏性、特异性、可靠性等应用特性进行研究。
创新要点:将ZnO压电薄膜作为产生GHz频段体声波谐振的功能层,通过设计激励电极,实现了在水中具有高Q值和高灵敏度的剪切波模式质量敏感换能器。在器件表面组装具有特异敏感性的生物抗体,实现对待测物质的生物识别;采用基于竞争性免疫反应的检测方法,达到对典型农药2×10−10 M的检测极限。
器件特色:基于薄膜电声谐振器的生物传感器,采用标准硅基半导体工艺进行制造,能够容易地实现大规模阵列和集成化。由于压电薄膜的谐振频率高,质量灵敏性比传统石英晶体高2个数量级。器件采用横向激励的剪切波模式谐振,在反应液中的Q值达到470,为生物免疫反应的在线检测提供了高性能的质量敏感平台。器件以生物免疫分子作为特异性吸附的功能层,采用竞争性反应吸附检测方法,解决了质量敏感的选择性问题。
重要结论:本文结合薄膜体声波电声谐振器的高质量敏感性和生物免疫反应的特异性,实现了一种高性能的农药残留生物传感器。该传感器灵敏度与传统检测方法相当,具有毫米量级器件尺寸,操作方法简单,并能够在线检测,有望成为目前复杂光学检测系统和电化学系统的替代技术。

关键词组:生物传感器;电声谐振器;农药残留;免疫反应


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DOI:

10.1631/jzus.C1300289

CLC number:

TP212.3

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On-line Access:

2014-05-06

Received:

2013-10-16

Revision Accepted:

2014-03-06

Crosschecked:

2014-04-11

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