Scanning electrochemical microscopy

Abstract

A new scanning electrochemical microscopy tip positioning method that allows topography and surface activity to be resolved independently is presented. A SECM tip is oscillated relative to the surface of interest. Changes in the oscillation amplitude, caused by the intermittent contact of the SECM tip with the surface of interest, are used to detect the surface of interest, and as a feedback signal for various types of imaging.

1 . A method comprising:
 oscillating a scanning microscopy probe tip relative to a surface of interest;   detecting damping of an amplitude of the oscillation of the probe tip resulting from the probe tip coming into contact with the surface of interest;   using the detected damping to detect the surface of interest; and   using the probe tip to measure or modify activity of the surface of interest simultaneously with detecting damping.   
     
     
         2 . A method as claimed in  claim 1 , comprising detecting damping during an approach curve procedure. 
     
     
         3 . A method as claimed in  claim 2 , comprising terminating the approach curve process when intermittent contact is detected. 
     
     
         4 . A method as claimed in  claim 2 , comprising terminating the approach curve process on detecting a sustained decrease in sensor tip oscillation amplitude as compared to oscillation amplitude in a reference medium. 
     
     
         5 . A method as claimed in  claim 2 , comprising terminating the approach curve process on detecting a decrease of between 0.5% and 15% in sensor tip oscillation amplitude as compared to oscillation amplitude in a reference medium. 
     
     
         6 . A method as claimed in  claim 2 , comprising terminating the approach curve process on detecting a decrease of about 5-10% in tip sensor oscillation amplitude as compared to oscillation amplitude in a reference medium. 
     
     
         7 . A method as claimed in  claim 1 , further comprising constructing an image using a series of line scans, each line scan including a forward intermittent contact scan and a reverse constant distance scan. 
     
     
         8 . A method according to  claim 1 , further comprising using a measured oscillation amplitude to control the probe tip movement relative to the surface of interest. 
     
     
         9 . A method as claimed in  claim 1 , wherein oscillating the probe tip comprises oscillating the probe tip with a magnitude of between 1% and 2% of the radius of the active electrode. 
     
     
         10 . A method according to  claim 1 , wherein the oscillation of the probe tip is selected from the group of:
 sinusoidal oscillation, sawtooth oscillation, and square oscillation.   
     
     
         11 . (canceled) 
     
     
         12 . (canceled) 
     
     
         13 . A method according to  claim 1 , in which a frequency of oscillation is selected from the group:
 between 5 and 100,000 Hz, between 5 and 5,000 Hz, and between 30 and 110 Hz.   
     
     
         14 . (canceled) 
     
     
         15 . (canceled) 
     
     
         16 . A method according to  claim 1 , in which an amplitude of oscillation is selected from the group:
 between 0.1 nm and 1 μm, between 5 nm and 500 nm, and between 15 nm and 250 nm.   
     
     
         17 . (canceled) 
     
     
         18 . (canceled) 
     
     
         19 . A method according to  claim 1 , in which the probe is selected from the group comprising:
 an ultramicroelectrode, an ion conductance probe, a fiber optic probe, and a potentiometric indicator probe.   
     
     
         20 . (canceled) 
     
     
         21 . (canceled) 
     
     
         22 . (canceled) 
     
     
         23 . A method according to  claim 1 , further comprising using a measured electrochemical response of the probe to provide information about the surface of interest. 
     
     
         24 . A method according to  claim 14 , in which the electrochemical response of the probe tip is the current generated at the probe tip when held at a potential to interact with a species of interest. 
     
     
         25 . A method according to  claim 14 , in which the electrochemical response of the probe tip is the potential generated at the probe tip when interacting with a species of interest. 
     
     
         26 . A method according to  claim 14 , comprising using the electrochemical response of the probe tip to deliver chemical species to the surface of interest. 
     
     
         27 . A method as claimed in  claim 1 , wherein oscillating of the probe tip is normal or generally normal to the surface of interest. 
     
     
         28 . (canceled) 
     
     
         29 . A non-transitory computer readable medium having stored thereon machine readable code that when executed by a processor of a scanning microscopy apparatus cause the apparatus to perform a method comprising:
 oscillating a probe tip relative to a surface of interest;   detecting damping of an amplitude of the oscillation of the probe tip resulting from the probe tip coming into contact with the surface of interest;   using the detected damping to detect the surface of interest; and   using the probe tip to measure or modify activity of the surface of interest simultaneously with detecting damping.   
     
     
         30 . Apparatus configured:
 to oscillate a scanning microscopy probe tip relative to a surface of interest;   to detect damping of an amplitude of the oscillation of the probe tip resulting from the probe tip coming into contact with the surface of interest;   to use the detected damping to detect the surface of interest; and   to use the probe tip to measure or modify activity of the surface of interest simultaneously with detecting damping.   
     
     
         31 . Apparatus comprising:
 means for oscillating a scanning microscopy probe tip relative to a surface of interest;   means for detecting damping of an amplitude of the oscillation of the probe tip resulting from the probe tip coming into contact with the surface of interest;   means for using the detected damping to detect the surface of interest; and   means for using the probe tip to measure or modify activity of the surface of interest simultaneously with detecting damping.