Measuring surface stress induced by electrode processes using a micromechanical sensor

Brunt, T. A.; Chabala, Evans D.; Rayment, Trevor; O’Shea, S. J.; Welland, Mark E.

doi:10.1039/ft9969203807

Cited by 47 publications

(39 citation statements)

References 32 publications

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“…1-11 To date, a variety of biomolecular interactions and chemical reactions have been translated into a nanoscale deflection of the cantilever: DNA hybridization, 12-21 ligand-receptor binding, 12,[22][23][24] (1) Lang protein-protein recognition, 12,17,25,26 cell adhesion, 27,28 alkanethiol self-assembly, 29-34 protonation/deprotonation of acid/ base groups, 35-39 metal ion complexation, 40-43 underpotential metaldeposition, [44][45][46][47][48] doping/dedopingofconductingpolymers, 49,50 and the swelling/collapse of polyelectrolyte brushes. [51][52][53][54][55] The basic principle is that a chemical or physical event occurring at the functionalized surface of one side of the cantilever generates a surface stress difference (between the active functionalized and passive nonfunctionalized sides) that causes the cantilever to bend away from its resting position.…”

Section: Introductionmentioning

confidence: 99%

Redox Actuation of a Microcantilever Driven by a Self-Assembled Ferrocenylundecanethiolate Monolayer: An Investigation of the Origin of the Micromechanical Motion and Surface Stress

Norman

Badia

2009

J. Am. Chem. Soc.

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The electrochemically induced motion of free-standing microcantilevers is attracting interest as micro/nanoactuators and robotic devices. The development and implementation of these cantilever-based actuating technologies requires a molecular-level understanding of the origin of the surface stress that causes the cantilever to bend. Here, we report a detailed study of the electroactuation dynamics of goldcoated microcantilevers modified with a model, redox-active ferrocenylundecanethiolate self-assembled monolayer (FcC 11 SAu SAM). The microcantilever transducer enabled the observation of the redox transformation of the surface-confined ferrocene. Oxidation of the FcC 11 SAu SAM in perchlorate electrolyte generated a compressive surface stress change of -0.20 ( 0.04 N m -1 , and cantilever deflections ranging from ∼0.8 µm to ∼60 nm for spring constants between ∼0.01 and ∼0.8 N m -1 . A comparison of the chargenormalized surface stress of the FcC 11 SAu cantilever with values published for the electrochemical oxidation of polyaniline-and polypyrrole-coated cantilevers reveals a striking 10-to 100-fold greater stress for the monomolecular FcC 11 SAu system compared to the conducting polymer multilayers used for electroactuation. The larger stress change observed for the FcC 11 SAu microcantilever is attributable to steric constraints in the close-packed FcC 11 SAu SAM and an efficient coupling between the chemisorbed FcC 11 S-monolayer and the Au-coated microcantilever transducer (vs physisorbed conducting polymers). The microcantilever deflection vs quantity of electrogenerated ferrocenium obtained in cyclic voltammetry and potential step/ hold experiments, as well as the surface stress changes obtained for mixed FcC 11 S-/C 11 SAu SAMs containing different populations of clustered vs isolated ferrocenes, have permitted us to establish the molecular basis of stress generation. Our results strongly suggest that the redox-induced deflection of a FcC 11 SAu microcantilever is caused by a monolayer volume expansion resulting from collective reorientational motions induced by the complexation of perchlorate ions to the surface-immobilized ferroceniums. The cantilever responds to the lateral pressure exerted by an ensemble of reorienting ferrocenium-bearing alkylthiolates upon each other rather than individual anion pairing events. This finding has general implications for using SAM-modified microcantilevers as (bio)sensors because it indicates that the cantilever responds to collective in-plane molecular interactions rather than reporting individual (bio)chemical events.

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Section: Introductionmentioning

confidence: 99%

Redox Actuation of a Microcantilever Driven by a Self-Assembled Ferrocenylundecanethiolate Monolayer: An Investigation of the Origin of the Micromechanical Motion and Surface Stress

Norman

Badia

2009

J. Am. Chem. Soc.

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“…When microcantilevers are treated as bending plates, their interfacial tension and the surface stress upon them cannot be measured directly. Experimental studies at the solid-electrolyte interface have focused on surface stress measurements during electrochemical processes [7][8][9][10][11][12]. Previous researchers have observed microcantilever bending in response to an applied potential or charge that takes place in the absence of electrolyte species, where the potential of zero charge correlated with a maximum (or minimum) in plots of surface stress vs. potential [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Observation of the surface stress induced in microcantilevers by electrochemical redox processes

Tian

Pei²,

Hedden³

et al. 2004

Ultramicroscopy

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“…15,24 In situ wafer/cantilever curvature techniques nicely complement traditional electrochemical measurements during electrodeposition. For example, cantilever curvature has been used to quantify the surface stress induced by surface charge (electrocapillarity) [25][26][27][28] and adsorption processes [29][30][31][32] as well as the growth stress associated with upd 25,[33][34][35][36][37][38][39][40][41][42][43][44] and the electrodeposition of bulk thin film. [45][46][47][48][49][50][51][52][53][54][55] This method is particularly useful in identifying structural changes, such as surface alloying, that may proceed without any electrochemical or nanogravimetric signature.…”

Section: (H 2 O)]mentioning

confidence: 99%

In Situ Stress Measurements during Cobalt Electrodeposition on (111)-Textured Au

Fayette

Bertocci

Stafford

2016

J. Electrochem. Soc.

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Cantilever curvature was used to examine stress generation during the electrodeposition of Co onto (111)-textured Au from 0.1 mol/L NaClO 4 + 0.001 mol/L Co(ClO 4 ) 2 (pH = 4.8) in films measuring less than 25 nm in thickness and at Co current efficiencies ranging from 65% to 90%. XRD analysis indicates that the Co is face-centered cubic and maintains the (111) texture of the Au substrate, suggesting epitaxial but not pseudomorphic growth on the Au. The stress-thickness product showed a −0.2 N/m compression in the first monolayer followed by increasing tensile stress as the film thickened. The initial compressive stress is most likely due to surface and interface stresses that dominate at submonolayer coverage. Steady state tensile stress, ranging from 0 to +450 MPa, developed in continuous Co films and showed a strong dependence on electrode potential. However, over this potential range there is no change in grain size or growth rate, factors typically associated with tensile stress. We attribute the tensile stress and its potential dependence to the formation of hydrogen stabilized vacancies, defects found to be quite stable in fcc Fe-group metals and alloys deposited under conditions of H + discharge. The use of electrodeposited Co-based materials has attracted much attention over the past several decades owing in part to their interesting magnetic 1-3 and catalytic properties. [4][5][6][7][8][9][10][11] These properties are largely dependent upon the structure and morphology of the electrodeposit, which in the case of cobalt can vary dramatically with overpotential, electrolyte pH, and the presence of strongly adsorbing anions. 2,[12][13][14][15][16]

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Measuring surface stress induced by electrode processes using a micromechanical sensor

Cited by 47 publications

References 32 publications

Redox Actuation of a Microcantilever Driven by a Self-Assembled Ferrocenylundecanethiolate Monolayer: An Investigation of the Origin of the Micromechanical Motion and Surface Stress

Redox Actuation of a Microcantilever Driven by a Self-Assembled Ferrocenylundecanethiolate Monolayer: An Investigation of the Origin of the Micromechanical Motion and Surface Stress

Observation of the surface stress induced in microcantilevers by electrochemical redox processes

In Situ Stress Measurements during Cobalt Electrodeposition on (111)-Textured Au

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