A differential microcantilever-based system for measuring surface stress changes induced by electrochemical reactions

We report on a differential microcantilever-based system capable of measuring surface stress changes which occur during electrochemical reactions. Surface stress changes induced by sub-monolayer ionic adsorption on metal surfaces and/or by electromechanical transformations in thin films can be measured. Our system is composed of two microcantilever sensors. The first active microcantilever serves as the working electrode (in a conventional three-probe electrochemical cell configuration) and as the mechanical transducer (bending of the microcantilever), yielding simultaneous, real-time, in situ measurements of the current and interfacial stress changes. The second reference microcantilever serves as a reference sensor to detect any unwanted cantilever deflection resulting from temperature variations, mechanical vibrations and/or uncontrolled chemical reactions. A technique for isolating the electrical contact made to the microcantilever from the electrolyte solution is presented. A method for creating a working electrode with a reproducible area of 1.0 mm 2 is also described. This micromechanical cantilever sensor has a deflection sensitivity of 0.2 nm, which translates to a surface stress sensitivity of 1 × 10 −4 N/m with a dynamic range of 5× 10 5 . The differential mode of this system has been characterized by measuring the potential-induced surface stress, at the Au(1 1 1) solid–liquid (HClO 4 electrolyte) interface, during anion (ClO 4 − ) adsorption on gold, while varying the solution temperature. Furthermore, we have measured the surface stress induced during ion doping/dedoping of dodecyl benzenesulfonate-doped polypyrrole (PPy(DBS)) films in an aqueous solution

[1]  I. Lundström,et al.  Microrobots for micrometer-size objects in aqueous media: potential tools for single-cell manipulation. , 2000, Science.

[2]  C. E. Bach,et al.  Potential-induced stress in the solid-liquid interface: Au(111) and Au(100) in an HClO4 electrolyte , 1997 .

[3]  Anja Boisen,et al.  A microcantilever-based alcohol vapor sensor-application and response model , 2000 .

[4]  H. Rothuizen,et al.  Translating biomolecular recognition into nanomechanics. , 2000, Science.

[5]  Stewart Sherrit,et al.  Characterization of the electromechanical properties of EAP materials , 2000, SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[6]  M. Welland,et al.  Measuring surface stress induced by electrode processes using a micromechanical sensor , 1996 .

[7]  Ernst Meyer,et al.  Nanomechanics from atomic resolution to molecular recognition based on atomic force microscopy technology , 2002 .

[8]  M. Fujihira,et al.  Calibration of surface stress measurements with atomic force microscopy , 1997 .

[9]  Mark E. Welland,et al.  Atomic force microscopy stress sensors for studies in liquids , 1996 .

[10]  W. Brantley.  Calculated elastic constants for stress problems associated with semiconductor devices , 1973 .

[11]  E. Smela.  Microfabrication of PPy microactuators and other conjugated polymer devices , 1999 .

[12]  Roberto Raiteri,et al.  Measuring Electrochemically Induced Surface Stress with an Atomic Force Microscope , 1995 .

[13]  James K. Gimzewski,et al.  Micromechanics: a toolbox for femtoscale science: “Towards a laboratory on a tip” , 1997 .

[14]  R. Nichols,et al.  Linear correlation between surface stress and surface charge in anion adsorption on Au(111) , 1998 .

[15]  Vincent Tabard-Cossa,et al.  Nanomechanical cantilever motion generated by a surface-confined redox reaction , 2003 .

[16]  M. Grattarola,et al.  Micromechanical cantilever-based biosensors , 2001 .

[17]  Michel Godin,et al.  Combined in situ micromechanical cantilever-based sensing and ellipsometry , 2003 .

[18]  N. Nicoloso,et al.  Microactuators based on conducting polymers , 2002, Analytical and bioanalytical chemistry.

[19]  Roberto Raiteri,et al.  Changes in surface stress at the liquid:solid interface measured with a microcantilever , 2000 .

[20]  I. Willner,et al.  Redox Activation of a Polyaniline-Coated Cantilever: An Electro-Driven Microdevice. , 2001, Angewandte Chemie.

[21]  M. Esashi,et al.  Fabrication of thermal microprobes with a sub-100 nm metal-to-metal junction , 2002 .

[22]  J. Sader,et al.  Calibration of rectangular atomic force microscope cantilevers , 1999 .

[23]  Peter Vettiger,et al.  A chemical sensor based on a micromechanical cantilever array for the identification of gases and vapors , 1998 .

[24]  Michel Godin,et al.  Surface stress, kinetics, and structure of alkanethiol self-assembled monolayers. , 2004, Langmuir : the ACS journal of surfaces and colloids.

[25]  M. Welland,et al.  Measuring the surface stresses in an electrochemically deposited metal monolayer : Pb on Au(111) , 1996 .