Sensor apparatus and method using optical interferometry

Abstract

A sensor apparatus and method includes a sensor head with at least two surfaces separated by a gap. One surface is mechanically fixed, a second surface is free to move and deflections of the second surface relative to the first surface are monitored by optical interferometry. In one embodiment, an optical fiber is used to direct light from a light source to the sensor and collect light reflected by the sensor. In alternate embodiments the sensor apparatus includes integrated optical elements, free-space optics, and direct laser-diode sensing. In operation, interaction of molecules or other objects in the sample with the second surface is detected as a change in amplitude and/or phase of deflection the second surface in response to an applied driving signal. A layer of binding molecules may be immobilized on the second surface and this surface exposed to a sample. The invention includes a method for detecting an analyte in a sample, including detecting the presence of analyte, the amount of analyte or the rate of association and/or dissociation of the analyte with a binding partner.

1 . A device comprising:
 a support including a first surface;   a second surface positioned proximate to the first surface, the second surface free to deflect in response to a driving force;   a driving means capable of generating a driving force to deflect the second surface;   a detector operable to monitor deflections of the second surface;   a sample including at least one analyte, the sample exposed to the second surface and the analyte able to interact with the second surface;   where interaction of the analyte with the second surface is detected as a change in the deflection of the second surface.   
     
     
         2 . The device of  claim 1  where the driving means is an external transducer. 
     
     
         3 . The device of claim where there the driving means is integrated into the device. 
     
     
         4 . The device of  claim 1  where the driving force is an electrostatic force. 
     
     
         5 . The device of  claim 1  where the driving means includes a transducer capable of generating acoustic or ultrasonic pressure waves. 
     
     
         6 . The device of  claim 1  where the second surface includes a film including a magnetized material disposed on at least one side of said second surface. 
     
     
         6 a. The device of  claim 1  where the second surface is electrically conductive. 
     
     
         7 . The device of  claim 1  where the driving means comprises:
 a signal source;   a magnetic field generator generating a magnetic field directed toward the second surface and driven by the signal source.   
     
     
         7 a. The device of  claim 1  where the driving means comprises:
 a signal source generating a current in the second surface:   a magnetic field generator,   where the magnetic field generates a force on the current in the second surface causing a deflection of the second surface.   
     
     
         8 . The device of  claim 1  including a synchronous detector with the signal from the detector monitoring second surface deflections as input and the signal from the driving means as reference. 
     
     
         9 . The device of  claim 1  where the detector is an optical interferometer capable of monitoring deflections of the second surface relative to the first surface. 
     
     
         10 . The device of  claim 1  where both first and second surfaces are capable of reflecting light. 
     
     
         11 . The device of  claim 1  where the second surface is a thin circular membrane held in tension 
     
     
         12 . The device of  claim 1  where the detector monitors changes in the amplitude of deflection of the second surface. 
     
     
         13 . The device of  claim 1  where the detector monitors changes in the phase of the deflection of the second surface relative to the phase of the driving force. 
     
     
         14 . The device of  claim 1  where the driving means operates in a pulsed mode and the dissipation of the oscillation of the second surface is monitored. 
     
     
         15 . The device of  claim 1  where the second surface includes a layer of analyte binding molecules. 
     
     
         16 . The device of  claim 1  operating to detect specific molecular binding of at least one analyze to the second surface. 
     
     
         17 . The device of  claim 1  where the sample is a fluid. 
     
     
         18 . The device of  claim 1  where specific analyte binding to the second surface changes the detected deflection of the second surface. 
     
     
         19 . A method of detecting analyte binding comprising;
 positioning a first surface proximate a second surface, the first surface including a   exposing the second surface to a sample including at least one analyte so that the analyte is free to internet with the second surface.   applying a driving force to deflect the second surface,   monitoring the deflection of the second surface in response to the driving force,   detecting the interaction of the analyte with the second surface as a change in the deflection of the second surface.   
     
     
         20 . A device comprising:
 a support including a first surface;   a second surface positioned proximate to the first surface;   a solenoid coil proximate the second surface;   a signal generator;   an optical interferometer monitoring deflections of the second surface;   a synchronous detector with the optical interferometer signal as input and the signal generator as reference;   a sample including at least one analyte;   where the first and second surfaces can reflect light,   where the second surface includes a magnetic film,   where the signal generator drives the solenoid coil to generate a magnetic field,   where the magnetic field generates a deflection of the second surface,   where the second surface is free to deflect in response to a driving force,   where the sample is exposed to second surface,   where the at least one analyte can specifically bind to the second surface,   where the optical interferometer measures the deflection of the second surface relative to the first surface,   where the synchronous detector monitors the amplitude of the second surface deflection,   where the synchronous detector monitors the phase of the second surface deflection relative to the phase of the signal generator,   where the binding of the analyte to the second surface is detected as a change in the deflection of the second surface and monitored by the synchronous detector.   
     
     
         20 a. A device comprising:
 a support including a first surface;   a second surface positioned proximate to the first surface;   a permanent magnet proximate the second surface;   a signal generator;   an optical interferometer monitoring deflections of the second surface;   a synchronous detector with the optical interferometer signal as input and the signal generator as reference;   a sample including at least one analyte;   where the first and second surfaces can reflect light,   where the second surface is free to deflect in response to a driving force,   where the second surface is electrically conductive,   where the sample is exposed to second surface,   where the at least one analyte can specifically bind to the second surface,   where the signal generator generates an electric current in the second surface,   where the optical interferometer measures the deflection of the second surface relative to the first surface,   where the synchronous detector monitors the amplitude of the second surface deflection,   where the synchronous detector monitors the phase of the second surface deflection relative to the phase of the signal generator,   where the binding of an analyte to the second surface is detected as a change in the deflection of the second surface and monitored by the synchronous detector.