ABSTRACT
The research on optical surface plasmon resonance (SPR) sensors for chemical and biological molecules
has experienced phenomenal expansion in the past two decades. The SPR phenomenon was reported by
Wood [1] in 1902 to describe the loss of light incident onto a grating. In 1957, surface plasmons (SPs)
were theoretically explained by Ritchie [2]. In 1968, Otto [3] presented the attenuated total reflection
(ATR) method to optically excite SP through an air gap [3]. Then Kretschmann proposed a more
practical approach, in which optical excitation of SPR through ATR is achieved without the aid of an air
gap [4]. Until today, this method has been the most popular technique for generating surface plasmon
wave (SPW). Practical SPR systems for detecting chemical and biological agents were first demonstrated by
Nylander and Liedberg in 1983 [5,6]. Since then SPR sensing techniques have attracted much attention in
the scientific and instrumentation communities, especially for applications concerned with biological
detection. The research for a biosensor that can measure molecular interactions of many types, like
antibody-antigen, receptor-ligand, protein-DNA, and so on is always on the top of the medical healthcare
list [7-9]. In recent years, R&D activities of SPR have been mainly directed toward biosensing applications,
which include drug screening and clinical studies, food and environmental monitoring, and cell mem-
brane mimicry. This is because of the potential of such sensors for applications in the health-related
market. Now, several companies are offering commercial SPR biosensor systems targeting at customers
conducting basic research in the field of life sciences. In fact, SPR biosensors have already become an
important tool for characterizing and quantifying biomolecular interactions in many laboratories.
Recently, applications of the SPR sensing technique are also expanding into the fields of environmental
pollution, chemistry, theoretical physics, and experimental optics. Our literature search shows that the
annual total number of research papers on SPR increased by almost 108-fold, from 6 to 651, during the
period of 1990-2002 [10,74-76]. This clearly indicates the technological importance of SPR sensors.
