Surface plasmon resonance sensor

Abstract

An SPR sensor comprising a thin conducting layer comprising at least one conductive element formed on a surface of a transparent substrate, a light source that illuminates an interface between the conducting layer and the substrate, a photosensitive surface that generates signals from light reflected from the interface, a flow cell formed with at least one flow channel having a lumen defined by a wall formed from an elastic material and from a region of the conducting layer, and at least one hollow fluid-providing flow control apparatus having a lumen and an orifice communicating with its lumen. Fluid flow is enabled between the flow channel and the lumen of the flow control apparatus by forcing an end of the flow control apparatus through the elastic material so that the orifice communicates with the flow channel lumen.

What is claimed is: 
     
         1 . A surface plasmon resonance (SPR) system using a ligand, the system comprising:
 a) a thin conducting layer suitable for SPR formed on a transparent substrate, the conducting layer comprising a plurality of electrodes;   b) at least one flow channel crossing the electrodes at crossover regions;   c) a power supply connected to the electrodes, and differently electrifying the electrodes at two different cross-over regions, such that the ligand flowing through the flow channel is attracted to and immobilized on the electrode at one of the cross-over regions, and repelled by and substantially prevented from immobilizing on the electrode at the other of the cross-over regions; and   d) a photosensitive surface that generates SPR signals in response to light reflected from the crossover region at which the ligand is immobilized, that can be used to determine an SPR parameter, and generates reference SPR signals in response to light reflected from the crossover region at which the ligand is prevented from immobilizing, that can be used to normalize and correct the SPR signals from the crossover region at which the ligand is immobilized.   
     
     
         2 . A system according to  claim 1 , wherein the at least one flow channel comprises a plurality of flow channels. 
     
     
         3 . A system according to  claim 2 , wherein the electrodes comprise a strip electrode crossed by the plurality of flow channels. 
     
     
         4 . A system according to  claim 2 , wherein the electrodes comprise a pixel electrode crossed by only one of the flow channels. 
     
     
         5 . A method for characterizing an interaction of a target material with a ligand on an SPR surface, the method comprising:
 a) electrifying a first electrode comprising a conducting layer suitable for SPR formed on a transparent substrate, so that it attracts the ligand;   b) electrifying a second electrode differently from the first electrode, so that it repels the ligand, the second electrode also comprising a conducting layer suitable for SPR formed on a transparent substrate;   c) passing a fluid containing the ligand through a flow channel crossed by the first and second electrodes while electrifying them, immobilizing the ligand on the first electrode and substantially not on the second electrode;   d) passing the target material through the flow channel after the ligand has been immobilized;   e) detecting light reflected from the first and second electrodes, after passing at least some of the target material through the flow channel;   f) generating SPR signals from the detected light reflected from the first electrode, and SPR reference signals from the detected light reflected from the second electrode; and   g) determining an SPR parameter that characterizes the interaction from the SPR signals, normalized and corrected by the SPR reference signals.   
     
     
         6 . A method according to  claim 5 , also comprising:
 a) electrifying a third electrode, comprising a conducting layer suitable for SPR formed on a transparent substrate, that also crosses the fluid channel, after the ligand is immobilized on the first electrode, while passing fluid containing a second ligand through the flow channel, so that the second ligand is attracted to and immobilized on the third electrode, and electrifying the first and second electrodes differently so that the second ligand is repelled by and substantially not immobilized on the first and second electrodes;   b) detecting light reflected from the third electrode, after passing at least some of the target material through the flow channel;   c) generating additional SPR signals from the detected light reflected from the third electrode; and   d) determining an SPR parameter characterizing an interaction of the target material with the second ligand from the additional SPR signals.