Patent Publication Number: US-2007109544-A1

Title: Surface Plasmon Resonance Sensing System

Description:
BACKGROUND OF THE INVENTION  
      (a) Field of the Invention  
      The present invention is related to a surface plasmon resonance (SPR) sensing system, and more particularly to an SPR sensing system, apparatus, and method excited by noble metal nanoparticles.  
      (b) Description of the Prior Art  
      Surface plasmon resonance phenomenon is that when a light source illuminates a metal surface at a fixed incident angle, the reflection intensity detected by a light detector would be near zero, which means the reflectivity of the metal film is near zero. The light which is not reflected will propagate along interface direction at a certain velocity to resonantly excite the surface plasmon of the metal. The method of measuring the reflected light is known as Attenuated Total Reflection (ATR).  
      A surface plasmon resonance sensing system uses a sensing system made by surface plasmon resonance phenomenon. Because the surface plasmon resonance sensor has high sensitivity, is label-free for detecting molecules, and can analyze the interaction between molecules at real-time. Other advantages include short analysis time and capability of simultaneous parallel detection. The system is therefore in widespread use on detecting biomolecules.  
      Recently, the development of nanomaterials is applied to optoelectronics, communication and medical equipment. Nanomaterials may provide specific characteristics which completely differ from traditional materials. The prior art works on localized surface plasmon resonance (LSPR) excited by noble metal nanoparticles to replace the conventional propagating surface plasmon resonance (PSPR) excited by gold film for additional advantages such as shorter electromagnetic field decay length, smaller pixel size, faster response time, and capability of simultaneous LSPR sensing and surface-enhanced Raman scattering. Furthermore, LSPR sensors can be constructed by simple and low-cost optical designs while PSPR sensors require bulky and expensive optical equipment. Today, the roadmap for the development of SPR sensor is heading for a miniaturized design. Should the SPR sensor be made in smaller size for easy portability and available in simpler design of detection method and operation performance, its applications could have been significantly extended.  
     SUMMARY OF THE INVENTION  
      The primary purpose of the present invention is to provide a surface plasmon resonance sensing system, apparatus, and method to further promote sensitivity of the sensing system, and reduce reaction time and consumption of test solution.  
      To achieve the foregoing object, an optical fiber is adapted instead of the conventional prism in the design of the sensing system since the optical fiber provides characteristics of low loss, high frequency band, free of EMI (electromagnetic interference), light-weighted, and small volume for significantly reducing the size of the sensing system. Whereas a micro-fluidic chip is essentially comprised of micro-fluidic devices including micro-fluidic channel, micro-pump, micro-valve, actuator, and micro-sensor for providing functions of multi-tasking process, movement, reaction, detection, and sample collection of test solution. The micro-fluidic chip is integrated in the present invention to further promote the sensitivity of the sensing system and reduce reaction time and consumption of the test solution.  
      Accordingly, the present invention is related to a surface plasmon resonance sensing system including an incidence illuminant, an optical fiber device, a noble metal nano-particles layer, a micro-fluidic module, and an illuminant detector. Wherein, the optical fiber device is an optical fiber where a portion of a protection layer and a cladding layer are stripped off; the noble metal nano-particle layer covers over the surface of the optical fiber device; the micro-fluidic module relates to a micro-fluidic chip to accommodate the optical fiber device and the sample; and the illuminant detector is operated to detect the emitted emergent light from the optical fiber device.  
      Whereas the present invention is adapted with the optical fiber with noble metal nano-particles instead of the conventional prism, the size of the SPR sensing system is significantly reduced, sensitivity further promoted, reaction time shortened, and consumption of test solution reduced by taking advantage of the micro-fluidic chip. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a schematic view showing a construction of optical fiber;  
       FIG. 2  is a schematic view showing that an optical fiber device is covered up by noble metal nano-particles;  
       FIG. 3  is a schematic view showing that a micro-fluidic chip is applied in the optical fiber sensing system;  
       FIG. 4  is a block chart of a surface plasmon resonance sensing system of the present invention;  
       FIG. 5  is a schematic view showing a preferred embodiment of the present invention; and  
       FIG. 6  is a process flow chart of the surface plasmon resonance sensing method of the present invention.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring to  FIG. 1  for a schematic view showing construction of an optical fiber, the optical fiber is essentially comprised of three layers, respectively the innermost a core  11 , a cladding  12  in the middle, an outermost protection  13  with materials and functions different from one another. As illustrated in  FIG. 2  for a schematic view showing the optical fiber device covered with noble metal nano-particles, the optical fiber device is an optical fiber wherein a portion of a protection layer and a cladding layer are stripped off and preserved only a core layer  21  and, if exist, a residual cladding layer  22 , and then a noble metal nano-particle layer  23  is covered up the surface of the optical fiber device. It should be noted that the cladding layer  22  could be totally stripped off to directly cover up the noble metal nano-particle layer.  
      The present invention is related to a sensing system integrated with a micro-fluidic chip and the optical fiber clad by noble metal nano-particles. Wherein, the micro-fluidic chip is essentially comprised of micro-fluidic devices including micro-fluidic channel, micro-pump, micro-valve, actuator, and micro-sensor to provide functions of multi-tasking process, movement, reaction, detection, and sample collection of the test sample. With the integrated micro-fluidic chip, the present invention further promotes the sensitivity of the sensing system and shortens the reaction time. As illustrated in  FIG. 3  showing that the micro-fluidic chip is applied in an optical fiber sensing system. A micro-fluidic chip  31  contains multiple micro-fluidic channels to accommodate the sample and an optical fiber device  32  and drives the sample to contact the noble metal nano-particles layer  33  on the surface of the optical fiber device  32 .  
      Now referring to  FIGS. 4 and 5  respectively show a block chart and a preferred embodiment of the present invention. The system includes an incidence illuminant  41 , an optical fiber device  42 , a noble metal nano-particle layer  43 , a micro-fluidic module  44 , and an illuminant detector  45 . Wherein, the incidence illuminant  41  relates to a single frequency light, a narrow band light or a white light; the optical fiber device  42  is related to an optical fiber where a portion of a protection layer and a cladding layer are stripped off; the noble metal nano-particle layer  43  is comprised of gold or silver nano-particles clad on the surface of the optical fiber device  42 ; the micro-fluidic module  44  is related to a micro-fluidic chip to accommodate the optical fiber device  42  and a sample  46  and drive the sample  46  to contact the noble metal nano-particle layer  43 ; the illuminant detector  45  is operated to detect an emergent light  47  from the optical fiber device  42 ; and the emergent light  47  may be related to a transmitted light, a reflected light, or leaked light from the region clad by noble metal nano-particles.  
      As illustrated in  FIG. 6  for the process flow chart of the SPR sensing method of the present invention, the process includes the following steps:  
      S 61 : Provide an incidence illuminant;  
      S 62 : Provide an optical fiber device;  
      S 63 : Prepare a noble metal nano-particle layer to cover up the surface of the optical fiber device;  
      S 64 : Provide a micro-fluidic module to drive the sample to contact the noble metal nano-particle layer; and  
      S 65 : Use an illuminant detector to detect the emergent light from the optical fiber device.  
      The noble metal nano-particle layer is comprised of gold or silver nano-particles.  
      It is to be noted that the preferred embodiments disclosed in the specification and the accompanying drawings are not limiting the present invention; and that any construction, installation, or characteristics that is same or similar to that of the present invention should fall within the scope of the purposes and claims of the present invention.