Sensors and Actuators B 137 (2009) 345–349 Contents lists available at ScienceDirect Sensors and Actuators B: Chemical journal homepage: www.elsevier.com/locate/snb Biochemistry nanosensor-based hybrid metallic nanostructures array Shaoli Zhu a,∗ , Chunlei Du a , Yongqi Fu b a Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, Sichuan Province, PR China b School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan Province, PR China article info Article history: Received 25 September 2008 Received in revised form 17 November 2008 Accepted 18 November 2008 Available online 27 November 2008 Keywords: Hybrid nanostructures Transmission Nanosensor LSPR abstract A biochemistry nanosensor was put forward on the basis of a new structure: hybrid metallic nanostructure array (spherical and pyramidal-shaped nanoparticles) in this paper. The hybrid metallic nanostructure array consists of two types of Ag nanostructures: spherical and pyramidal structures patterned with the same period. Design, fabrication and characterization of the Ag nanostructures were presented. Rele- vant experimental results were obtained by means of detecting the transmittance spectra of the hybrid metallic nanostructure. Apparent shifting of peak wavelength of the transmittance spectra occurs while varies the periods and the effective refractive index of surrounding mediums. Moreover, there are some sharp and narrow peaks of the transmittance spectra by which it can improve the resolving power of the biochemistry nanosensor. Crown Copyright © 2008 Published by Elsevier B.V. All rights reserved. 1. Introduction Recently, biochemistry nanosensor is an active research topic in both life sciences and engineering [1]. It involves the interdis- ciplinary areas of life sciences and information sciences such as bioinformatics, biochemistry chip, biocybernetics, bionics, and bio- computer. Their common characteristics are exploring and opening out the basic rules for the production, storage, transmission, pro- cess, transition, and control of the information in the biological systems, and discussing the basic methods which are employed for the human economy activity. The biosensor related research focuses on combination of the sensors and the diversified biological active materials as well as their relevant applications. The localized surface plasmon resonance (LSPR)-based nanosensor becomes the hotspot problem because they have begun development situation and important position in the life sciences research [2–8]. LSPR nanosensor can be imple- mented using extremely simple, small, light, robust, and low cost equipments. It has many advantages such as convenience, high sen- sitivity, wide application and real-time detection. Thus it is deemed to be a type of furthest potential biosensor. Optical properties of the metal nanoparticles’ mainly depend on their size, shape, metal composition and the refractive index of the surrounding mediums. Previous research has shown that the LSPR-based nanosensor, is a refractive index-based sensing device which strongly relies on the extraordinary optical properties of noble (e.g., Ag, Au and Cu) metal ∗ Corresponding author. Tel.: +65 6790 5985 11. E-mail address: slzhu@ntu.edu.sg (S. Zhu). nanoparticles [9–12]. The Ag nanoparticles have endowed the device with excellent optical characteristics. Especially, the peak wavelength of the transmittance spectrum  max is unexpectedly sensitive to size and shape of the nanoparticle, and local external dielectric environment. Its sensitivity to the nanoenvironment has given us the foundation to develop a new serial of nanoscale affinity biochemosensors. In this paper, we proposed a new type of hybrid metallic nanostructure array which consists of two shapes of nanostructures: spherical and pyramidal structures with the same period. The former is composed of Ag and polystyrene, and the latter is pure Ag nanoparticles only. The hybrid metallic nanostructure array can excite the LSPR phenomena and there are some sharp and narrow peaks of the transmittance spectra which can improve the resolving power of the biochemistry nanosensor. 2. Design theory of the biochemistry nanosensor A local surface plasma wave (LSPW) will be excited when the incident photon frequency is resonant with the collective oscilla- tion of the conduction electrons and is known as the LSPR. The LSPR spectrum is the connection curve between the incident wavelength and the absorption spectrum. The LSPR spectrum peak wavelengths are sensitive to the electric mediums on surface of the metals. Using this characteristic, we can fabricate the LSPR-based biosensor. The characteristic and functioning mechanism of our LSPR-based biochemosensor are employment of a layer of inorganic adhesive so as to change the effective refractive index of the surrounding medium. We measured the variation of the refractive index of the surrounding mediums so as to know the effect on optical proper- ties of the nanosensor. Our design is using two Ag layers for the 0925-4005/$ – see front matter. Crown Copyright © 2008 Published by Elsevier B.V. All rights reserved. doi:10.1016/j.snb.2008.11.019