Cantilevered probes having piezoelectric layer, treated section, and resistive heater, and method of use for chemical detection

Abstract

The invention provides a liquid cell for an atomic force microscope. The liquid cell includes a liquid cell housing with an internal cavity to contain a fluid, a plurality of conductive feedthroughs traversing the liquid cell housing between the internal cavity and a dry side of the liquid cell, a cantilevered probe coupled to the liquid cell housing, and a piezoelectric drive element disposed on the cantilevered probe. The cantilevered probe is actuated when a drive voltage is applied to the piezoelectric drive element through at least one of the conductive feedthroughs. A method of imaging an object in a liquid medium and a method of sensing a target species with the liquid cell are also disclosed.

What is claimed is: 
     
         1 . A chemical sensor system comprising:
 a first cantilevered probe comprising:
 a piezoelectric layer; 
 a treated section selected to react with a chemical species; 
 a resistive heater thermally couplable to the treated section; and 
 first and second electrodes electrically coupled to the piezoelectric layer; 
   a driver circuit electrically coupled to the first and second electrodes and configured to actuate the cantilevered probe;   a sensing circuit electrically coupled to the first and second electrodes and configured to sense oscillation of the cantilevered probe;   a heater circuit electrically coupled to the resistive heater; and   a plurality of additional cantilevered probes arranged in an array together with the first cantilevered probe, each of the plurality of additional cantilevered probes comprising:
 a piezoelectric layer; and 
 first and second electrodes electrically coupled to the piezoelectric layer; 
   wherein the first cantilevered probe is actuated when, through the first and second electrodes, a drive voltage is applied to the piezoelectric layer by the driver circuit, the actuated cantilevered probe generating a displacement signal transmitted to the sensing circuit, and wherein the piezoelectric layers of each of the cantilevered probes of the array are connected in parallel.   
     
     
         2 . The sensor system of  claim 1 , wherein each of the plurality of additional cantilevered probes comprises a resistive heater; and
 an electrical lead electrically coupled to the heater circuit and each of the resistive heaters of the plurality of additional cantilevered probes.   
     
     
         3 . The sensor system of  claim 1 , wherein the resistive heater is formed as one piece with the cantilevered probe. 
     
     
         4 . The sensor system of  claim 1 , further comprising a passivation layer disposed on the piezoelectric layer of the first cantilevered probe. 
     
     
         5 . The sensor system of  claim 1 , wherein at least two of the array of cantilevered probes having a treated section different from one another. 
     
     
         6 . The sensor system of  claim 1 , wherein at least one of the array of cantilevered probes having a treated section and at least one of the array of cantilevered probes not having a treated section. 
     
     
         7 . The sensor system of  claim 1 , wherein at least one of the array of cantilevered probes having a temperature sensing element. 
     
     
         8 . A method of determining the composition of a sample comprising:
 providing a first cantilevered probe and a plurality of additional cantilevered probes arranged in an array together with the first cantilevered probe,
 the first cantilevered probe comprising:
 a piezoelectric layer; 
 a resistive heater; 
 a treated section; 
 a first electrode electrically coupled to the piezoelectric layer; and 
 a second electrode electrically coupled to the piezoelectric layer; and 
 
 each of the plurality of additional cantilevered probes comprising:
 a piezoelectric layer; and 
 first and second electrodes electrically coupled to the piezoelectric layer; 
 
 wherein the piezoelectric layers of each of the cantilevered probes of the array are connected in parallel; 
   driving the first cantilevered probe by applying an excitation voltage to the piezoelectric layer;   sensing vibration of the first cantilevered probe by measuring a signal generated by the piezoelectric element;   exposing the treated section to a sample; and   after exposing the treated section to the sample, sensing vibration of the first cantilevered probe by measuring a signal generated by the piezoelectric element.   
     
     
         9 . The method of  claim 8  wherein exposing the treated section to a sample comprises exposing the treated section to a liquid sample. 
     
     
         10 . The method of  claim 8  further comprising heating at least one of the array of cantilevered probes and sensing the temperature of the heated array. 
     
     
         11 . A chemical sensor system comprising:
 a first cantilevered probe comprising:
 a piezoelectric layer; 
 a resistive heater thermally couplable to the surface of the first cantilevered probe; and 
 first and second electrodes electrically coupled to the piezoelectric layer; 
   a driver circuit electrically coupled to the first and second electrodes and configured to actuate the cantilevered probe;   a sensing circuit electrically coupled to the first and second electrodes and configured to sense oscillation of the cantilevered probe;   a heater circuit electrically coupled to the resistive heater; and   a plurality of additional cantilevered probes arranged in an array together with the first cantilevered probe, each of the plurality of additional cantilevered probes comprising:
 a piezoelectric layer; and 
 first and second electrodes electrically coupled to the piezoelectric layer; 
   wherein the first cantilevered probe is actuated when, through the first and second electrodes, a drive voltage is applied to the piezoelectric layer by the driver circuit, the actuated cantilevered probe generating a displacement signal transmitted to the sensing circuit, and wherein the piezoelectric layers of each of the cantilevered probes of the array are connected in parallel.   
     
     
         12 . The sensor system of  claim 11 , wherein each of the plurality of additional cantilevered probes comprises a resistive heater; and
 an electrical lead electrically coupled to the heater circuit and each of the resistive heaters of the plurality of additional cantilevered probes.   
     
     
         13 . The sensor system of  claim 11 , further comprising a passivation layer disposed on the piezoelectric layer of the first cantilevered probe. 
     
     
         14 . The sensor system of  claim 11 , wherein at least one of the array of cantilevered probes having a treated section and at least one of the array of cantilevered probes not having a treated section. 
     
     
         15 . The sensor system of  claim 11 , wherein at least one of the array of cantilevered probes having an element capable of temperature sensing. 
     
     
         16 . The sensor system of  claim 11 , wherein the first cantilevered probe further comprises a treated section selected to react with a chemical species.