101
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102
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Srinivasan V, Cicero G, Grossman JC. Adsorption-induced surface stresses in alkanethiolate-au self-assembled monolayers. PHYSICAL REVIEW LETTERS 2008; 101:185504. [PMID: 18999840 DOI: 10.1103/physrevlett.101.185504] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Indexed: 05/27/2023]
Abstract
First-principles calculations were employed to elucidate the origin of adsorption-induced surface stresses in alkanethiolate self-assembled monolayers on an Au(111) surface. Our results suggest a mechanism that accounts for the huge relief of the tensile stress compared to the bare surface in terms of a local rearrangement of surface Au atoms accompanying charge removal from the surface towards the Au-S bond. A purely interadsorbate interaction model is shown to be inconsistent with the anisotropy and the magnitude of the calculated stress.
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Affiliation(s)
- Varadharajan Srinivasan
- Berkeley Nanoscience and Nanoengineering Institute, University of California, Berkeley, California 94720, USA
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103
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Zangmeister C, Bertocci U, Beauchamp C, Stafford G. In situ stress measurements during the electrochemical adsorption/desorption of self-assembled monolayers. Electrochim Acta 2008. [DOI: 10.1016/j.electacta.2007.12.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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104
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Computational analysis of mechanical stresses induced by self-assembled monolayer molecules on micro-cantilever. J Biotechnol 2008. [DOI: 10.1016/j.jbiotec.2008.07.639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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105
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Hill K, Dutta P, Zareba A, Eldridge ML, Sepaniak MJ. Morphological and chemical optimization of microcantilever surfaces for thyroid system biosensing and beyond. Anal Chim Acta 2008; 625:55-62. [DOI: 10.1016/j.aca.2008.07.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2008] [Revised: 06/25/2008] [Accepted: 07/04/2008] [Indexed: 10/21/2022]
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106
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Raorane D, Lim SHS, Majumdar A. Nanomechanical assay to investigate the selectivity of binding interactions between volatile benzene derivatives. NANO LETTERS 2008; 8:2229-2235. [PMID: 18616329 DOI: 10.1021/nl080829s] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Understanding the interactions between aromatic gas molecules and various simple aromatic receptor molecules is important in developing selective receptors for volatile organic compounds (VOCs). Here, five benzene thiols with different functional end groups were used to investigate the weak binding of aromatic vapors such as dinitrotolouene (DNT) and toluene. A multiplexed microcantilever array in conjunction with a very low concentration vapor generation system was developed to study multiple receptor-target interactions simultaneously. Differential nanomechanical responses of such devices provided insight into the influence of various chemical and structural features of such molecules.
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Affiliation(s)
- Digvijay Raorane
- Department of Mechanical Engineering, University of California, Berkeley, Berkeley, California 94704, USA
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107
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Raman Suri C, Kaur J, Gandhi S, Shekhawat GS. Label-free ultra-sensitive detection of atrazine based on nanomechanics. NANOTECHNOLOGY 2008; 19:235502. [PMID: 21825795 DOI: 10.1088/0957-4484/19/23/235502] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The alarming increase in the amount of dangerous pesticides such as atrazine in agricultural fields and drinking water is driving the growth of new technologies to detect these toxins well below their threat level. The recent elucidation of microcantilever nanomechanical bending in response to chemical and biomolecular interactions has added another significant facet to biochemical engineering research and has fostered the development of a variety of signal detection paradigms, at both the microscale and the nanoscale. We report the label-free detection of highly specific atrazine antibody-antigen interactions at the nanometer scale on microcantilevers, with 1 ppt (past per trillion) sensitivity. The chemical interaction-induced deflection of the cantilever beam reflects the interplay between the strain energy increase of the cantilever and the free energy reduction of the reaction, providing a unique system for investigating the connection between the nanomechanics and the chemistry of antibody-antigen interaction at picomolar concentration with nanometer resolution. Cantilevers were functionalized with highly specific and site-directed anti-atrazine antibodies and exposed to target antigen over a wide range of concentration from 4.65 pM to 46.5 µM of varying sequence in static and flow conditions. Antibody-antigen interaction of atrazine with the specific antibody resulted in net negative deflection of the cantilever. The results show that high specificity and site-directed antibody immobilization lead to ultra-high sensitivity detection of atrazine. The measurements provide results within minutes at the picomolar level, and exhibit high target specificity. This qualifies the technology as a rapid method to validate organic toxins and its progression.
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Affiliation(s)
- C Raman Suri
- Institute for Microbial Technology, Chandigarh 160036, India
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108
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Baker GA, Desikan R, Thundat T. Label-Free Sugar Detection Using Phenylboronic Acid-Functionalized Piezoresistive Microcantilevers. Anal Chem 2008; 80:4860-5. [DOI: 10.1021/ac702588b] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Gary A. Baker
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, Biological Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, and Department of Physics, The University of Tennessee, Knoxville, Tennesse 37996
| | - Ramya Desikan
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, Biological Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, and Department of Physics, The University of Tennessee, Knoxville, Tennesse 37996
| | - Thomas Thundat
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, Biological Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, and Department of Physics, The University of Tennessee, Knoxville, Tennesse 37996
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109
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Cha M, Shin J, Kim JH, Kim I, Choi J, Lee N, Kim BG, Lee J. Biomolecular detection with a thin membrane transducer. LAB ON A CHIP 2008; 8:932-937. [PMID: 18497914 DOI: 10.1039/b719101d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We present a thin membrane transducer (TMT) that can detect nucleic acid based biomolecular reactions including DNA hybridization and protein recognition by aptamers. Specific molecular interactions on an extremely thin and flexible membrane surface cause the deflection of the membrane due to surface stress change which can be measured by a compact capacitive circuit. A gold-coated thin PDMS membrane assembled with metal patterned glass substrate is used to realize the capacitive detection. It is demonstrated that perfect match and mismatch hybridizations can be sharply discriminated with a 16-mer DNA oligonucleotide immobilized on the gold-coated surface. While the mismatched sample caused little capacitance change, the perfectly matched sample caused a well-defined capacitance decrease vs. time due to an upward deformation of the membrane by a compressive surface stress. Additionally, the TMT demonstrated the single nucleotide polymorphism (SNP) capabilities which enabled a detection of mismatching base pairs in the middle of the sequence. It is intriguing that the increase of capacitance, therefore a downward deflection due to tensile stress, was observed with the internal double mismatch hybridization. We further present the detection of thrombin protein through ligand-receptor type recognition with 15-mer thrombin aptamer as a receptor. Key aspects of this detection such as the effect of concentration variation are investigated. This capacitive thin membrane transducer presents a completely new approach for detecting biomolecular reactions with high sensitivity and specificity without molecular labelling and optical measurement.
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Affiliation(s)
- Misun Cha
- School of Mechanical and Aerospace Engineering, Seoul National University, San 56-1, Shinlim, Kwanak, Seoul, 151-742, Korea
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110
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Abstract
This review will provide a general introduction to the field of cantilever biosensors by discussing the basic principles and the basic technical background necessary to understand and evaluate this class of sensors. Microfabricated cantilever sensors respond to changes in their environment or changes on their surface with a mechanical bending in the order of nanometers which can easily be detected. They are able to detect pH and temperature changes, the formation of self-assembled monolayers, DNA hybridization, antibody-antigen interactions, or the adsorption of bacteria. The review will focus on the surface stress mode of microfabricated cantilever arrays and their application as biosensors in molecular life science. A general background on biosensors, an overview of the different modes of operation of cantilever sensors and some details on sensor functionalization will be given. Finally, key experiments and current theoretical efforts to describe the surface stress mode of cantilever sensors will be discussed.
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Affiliation(s)
- Jürgen Fritz
- Jacobs University Bremen, School of Engineering and Science, Campus Ring 1, 28759 Bremen, Germany.
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111
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Toda M, Itakura AN, Igarashi S, Büscher K, Gutmann JS, Graf K, Berger R. Surface stress, thickness, and mass of the first few layers of polyelectrolyte. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:3191-3198. [PMID: 18303921 DOI: 10.1021/la7028214] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The effects of surface stress and mass loading upon the adsorption of polyelectrolytes onto flexible silicon micromechanical cantilever sensors (MCSs) were studied in situ. A self-assembled monolayer of 2-mercaptoethylamine chloride (2-MEA) on gold was used to achieve single-side adsorption on the MCS. Such a preparation gave a positive surface potential, whereas a bare SiOx surface gave a negative surface potential. Wide scan X-ray photoelectron spectroscopy confirmed that the adsorption of polystyrenesulfonate (PSS) and polyallylamine hydrochloride (PAH) followed the general rule expected from the electrostatic interaction between the substrate and the polyelectrolyte, whereas the adsorption polyethyleneimine (PEI) did not. The adsorption of PAH on SiO(x) from a 3 mM water solution containing 1 M NaCl was associated with a deflection of the MCS toward the polyelectrolyte monolayer (tensile surface stress) owing to the hydrogen bonding between neighboring amino groups. Here, a surface stress change of 1.4 +/- 0.1 N/m was estimated. The adsorption of PSS from a 3 mM water solution containing 1 M NaCl on a 2-MEA surface induced a deflection of the MCS away from the polyelectrolyte layer (compressive stress), toward the SiO(x) side. Here, a surface stress change of 3.1 +/- 0.3 N/m was determined. The formation of a PAH layer on top of the PSS layer resulted in a deflection of the MCS toward the PAH layer. This indicated that the adjacent PSS layer was deswelling, corresponding to a surface stress change of 0.5 +/- 0.1 N/m.
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Affiliation(s)
- Masaya Toda
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz D-55128, Germany
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112
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Comrie JE, Huck WTS. Exploring Actuation and Mechanotransduction Properties of Polymer Brushes. Macromol Rapid Commun 2008. [DOI: 10.1002/marc.200700682] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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113
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Nordström M, Keller S, Lillemose M, Johansson A, Dohn S, Haefliger D, Blagoi G, Havsteen-Jakobsen M, Boisen A. SU-8 Cantilevers for Bio/chemical Sensing; Fabrication, Characterisation and Development of Novel Read-out Methods. SENSORS 2008; 8:1595-1612. [PMID: 27879783 PMCID: PMC3663014 DOI: 10.3390/s8031595] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2007] [Accepted: 03/03/2008] [Indexed: 11/16/2022]
Abstract
Here, we present the activities within our research group over the last five yearswith cantilevers fabricated in the polymer SU-8. We believe that SU-8 is an interestingpolymer for fabrication of cantilevers for bio/chemical sensing due to its simple processingand low Young's modulus. We show examples of different integrated read-out methodsand their characterisation. We also show that SU-8 cantilevers have a reduced sensitivity tochanges in the environmental temperature and pH of the buffer solution. Moreover, weshow that the SU-8 cantilever surface can be functionalised directly with receptormolecules for analyte detection, thereby avoiding gold-thiol chemistry.
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Affiliation(s)
- Maria Nordström
- MIC - Department of Micro and Nanotechnology, Technical University of Denmark, DTU building 345 East, DK-2800 Kongens Lyngby, Denmark.
| | - Stephan Keller
- MIC - Department of Micro and Nanotechnology, Technical University of Denmark, DTU building 345 East, DK-2800 Kongens Lyngby, Denmark
| | - Michael Lillemose
- MIC - Department of Micro and Nanotechnology, Technical University of Denmark, DTU building 345 East, DK-2800 Kongens Lyngby, Denmark
| | | | - Søren Dohn
- MIC - Department of Micro and Nanotechnology, Technical University of Denmark, DTU building 345 East, DK-2800 Kongens Lyngby, Denmark
| | | | - Gabriela Blagoi
- MIC - Department of Micro and Nanotechnology, Technical University of Denmark, DTU building 345 East, DK-2800 Kongens Lyngby, Denmark
| | - Mogens Havsteen-Jakobsen
- MIC - Department of Micro and Nanotechnology, Technical University of Denmark, DTU building 345 East, DK-2800 Kongens Lyngby, Denmark
| | - Anja Boisen
- MIC - Department of Micro and Nanotechnology, Technical University of Denmark, DTU building 345 East, DK-2800 Kongens Lyngby, Denmark
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114
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Viswanath R, Kramer D, Weissmüller J. Adsorbate effects on the surface stress–charge response of platinum electrodes. Electrochim Acta 2008. [DOI: 10.1016/j.electacta.2007.10.049] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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115
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Carlen ET, Weinberg MS, Zapata AM, Borenstein JT. A micromachined surface stress sensor with electronic readout. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2008; 79:015106. [PMID: 18248065 DOI: 10.1063/1.2830938] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
A micromachined surface stress sensor has been fabricated and integrated off chip with a low-noise, differential capacitance, electronic readout circuit. The differential capacitance signal is modulated with a high frequency carrier signal, and the output signal is synchronously demodulated and filtered resulting in a dc output voltage proportional to the change in differential surface stress. The differential surface stress change of the Au(111) coated silicon sensors due to chemisorbed alkanethiols is Deltasigma(s) approximately -0.42+/-0.0028 N m(-1) for 1-dodecanethiol (DT) and Deltasigma(s) approximately -0.14+/-0.0028 N m(-1) for 1-butanethiol (BT). The estimated measurement resolution (1 Hz bandwidth) is approximately 0.12 mN m(-1) (DT: 0.2 pg mm(-2) and BT: 0.8 pg mm(-2)) and as high as approximately 3.82 microN m(-1) (DT: 8 fg mm(-2) and BT: 24 fg mm(-2)) with system optimization.
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Affiliation(s)
- Edwin T Carlen
- The Charles Stark Draper Laboratory, 555 Technology Square, Cambridge, Massachusetts 02139, USA.
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116
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Snow D, Weeks BL, Kim DJ, Loui A, Hart BR, Hope-Weeks LJ. Static deflection measurements of cantilever arrays reveal polymer film expansion and contraction. J Colloid Interface Sci 2007; 316:687-93. [PMID: 17904571 DOI: 10.1016/j.jcis.2007.08.050] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Revised: 08/21/2007] [Accepted: 08/21/2007] [Indexed: 11/25/2022]
Abstract
An optical static method of detection is used to interpret surface stress induced bending related to cantilevers coated on one side with poly(vinyl alcohol), poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate), and poly(vinyl chloride-co-vinyl acetate-co-2-hydroxypropyl acrylate), or respectively, PVA, PVB, and PVC, and exposed to various solvent vapors. Results indicate that the adsorption and surface interactions of the different solvent vapors that cause polymer swelling and shrinking lead to rearrangements, which have been shown to change the elastic properties of the polymer film, and subsequently, the spring constant of the polymer coated cantilever. Static deflection measurements allow the direction of cantilever bending to be determined, which adds a new dimension of usefulness for surface functionalized cantilevers as transducers in the development of novel microelectromechanical systems (MEMS).
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Affiliation(s)
- David Snow
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
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117
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Bergese P, Oliviero G, Alessandri I, Depero LE. Thermodynamics of mechanical transduction of surface confined receptor/ligand reactions. J Colloid Interface Sci 2007; 316:1017-22. [PMID: 17889897 DOI: 10.1016/j.jcis.2007.08.048] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2007] [Revised: 08/20/2007] [Accepted: 08/21/2007] [Indexed: 10/22/2022]
Abstract
Chemomechanics of surface stress is discussed in terms of interfacial thermodynamics. In the first section the paper shows how to quantitatively describe the chemical equilibrium of a receptor/ligand binding reaction confined at a solid-liquid interface and how the overall work of the reaction splits into chemical and surface work, that appears as a surface pressure. In the second section this thermodynamic model is applied to describe the experimental results of microcantilever bending induced by DNA hybridization occurring onto one of its faces.
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Affiliation(s)
- Paolo Bergese
- INSTM and Chemistry for Technologies Laboratory, University of Brescia, via Branze 38, 25123 Brescia, Italy.
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118
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Lachut MJ, Sader JE. Effect of surface stress on the stiffness of cantilever plates. PHYSICAL REVIEW LETTERS 2007; 99:206102. [PMID: 18233163 DOI: 10.1103/physrevlett.99.206102] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Indexed: 05/25/2023]
Abstract
Measurements over the past 30 years have indicated that surface stress can significantly affect the stiffness of microcantilever plates. Several one-dimensional models based on beam theory have been proposed to explain this phenomenon, but are found to be in violation of Newton's third law, in spite of their good agreement with measurements. In this Letter, we review this work and rigorously examine the effect of surface stress on the stiffness of cantilever plates using a full three-dimensional model. This study establishes the relationship between surface stress and cantilever stiffness, and in so doing elucidates its scaling behavior with cantilever dimensions. The use of short nanoscale cantilevers thus presents the most promising avenue for future investigations.
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Affiliation(s)
- Michael J Lachut
- Department of Mathematics and Statistics, The University of Melbourne, Victoria 3010, Australia
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119
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Tabard-Cossa V, Godin M, Burgess IJ, Monga T, Lennox RB, Grütter P. Microcantilever-Based Sensors: Effect of Morphology, Adhesion, and Cleanliness of the Sensing Surface on Surface Stress. Anal Chem 2007; 79:8136-43. [PMID: 17914755 DOI: 10.1021/ac071243d] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The surface stress response of micromechanical cantilever-based sensors was studied as a function of the morphology, adhesion, and cleanliness of the gold sensing surface. Two model systems were investigated: the adsorption of alkanethiol self-assembled monolayers at the gas-solid interface and the potential-controlled adsorption of anions at the liquid-solid interface. The potential-induced surface stress, on a smooth and continuous polycrystalline Au(111)-textured microcantilever in 0.1 M HClO4, is in excellent agreement with macroscopic Au(111) single-crystal electrode results. It is shown that ambient contaminants on the sensing surface dramatically alter the surface stress-potential response. This observation can be misinterpreted as evidence that for polycrystalline Au(111) microcantilever electrodes, surface stress is dominated by surface energy change. Results for anions adsorption on gold are in contrast to the gas-phase model system. We demonstrate that the average grain size of the gold sensing surface strongly influences the magnitude of the surface stress change induced by the adsorption of octanethiol. A 25-fold amplification of the change in surface stress is observed on increasing the average gold grain size of the sensing surface from 90 to 500 nm.
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120
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Waggoner PS, Craighead HG. Micro- and nanomechanical sensors for environmental, chemical, and biological detection. LAB ON A CHIP 2007; 7:1238-55. [PMID: 17896006 DOI: 10.1039/b707401h] [Citation(s) in RCA: 245] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Micro- and nanoelectromechanical systems, including cantilevers and other small scale structures, have been studied for sensor applications. Accurate sensing of gaseous or aqueous environments, chemical vapors, and biomolecules have been demonstrated using a variety of these devices that undergo static deflections or shifts in resonant frequency upon analyte binding. In particular, biological detection of viruses, antigens, DNA, and other proteins is of great interest. While the majority of currently used detection schemes are reliant on biomarkers, such as fluorescent labels, time, effort, and chemical activity could be saved by developing an ultrasensitive method of label-free mass detection. Micro- and nanoscale sensors have been effectively applied as label-free detectors. In the following, we review the technologies and recent developments in the field of micro- and nanoelectromechanical sensors with particular emphasis on their application as biological sensors and recent work towards integrating these sensors in microfluidic systems.
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Affiliation(s)
- Philip S Waggoner
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA
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121
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Wehrmeister J, Fuss A, Saurenbach F, Berger R, Helm M. Readout of micromechanical cantilever sensor arrays by Fabry-Perot interferometry. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2007; 78:104105. [PMID: 17979440 DOI: 10.1063/1.2785028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The increasing use of micromechanical cantilevers in sensing applications causes a need for reliable readout techniques of micromechanical cantilever sensor (MCS) bending. Current optical beam deflection techniques suffer from drawbacks such as artifacts due to changes in the refraction index upon exchange of media. Here, an adaptation of the Fabry-Perot interferometer is presented that allows simultaneous determination of MCS bending and changes in the refraction index of media. Calibration of the instrument with liquids of known refraction index provides an avenue to direct measurement of bending with nanometer precision. Versatile construction of flow cells in combination with alignment features for substrate chips allows simultaneous measurement of two MCS situated either on the same, or on two different support chips. The performance of the instrument is demonstrate in several sensing applications, including adsorption experiments of alkanethioles on MCS gold surfaces, and measurement of humidity changes in air.
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Affiliation(s)
- Jana Wehrmeister
- Institut für Pharmazie und Molekulare Biotechnologie, Department of Chemistry, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 364, D-69120 Heidelberg, Germany
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122
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Dutta P, Hill K, Datskos PG, Sepaniak MJ. Development of a nanomechanical biosensor for analysis of endocrine disrupting chemicals. LAB ON A CHIP 2007; 7:1184-91. [PMID: 17713618 DOI: 10.1039/b704723a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
A nanomechanical transducer is developed to detect and screen endocrine disrupting chemicals (EDCs) combining fluidic sample injection and delivery with bioreceptor protein functionalized microcantilevers (MCs). The adverse affects of EDCs on the endocrine system of humans, livestock, and wildlife provides strong motivation for advances in analytical detection and monitoring techniques. The combination of protein receptors, which include estrogen receptor alpha (ER-alpha) and estrogen receptor beta (ER-beta), as well as monoclonal antibodies (Ab), with MC systems employing modified nanostructured surfaces provides for excellent nanomechanical response sensitivity and the inherent selectivity of biospecific receptor-EDC interactions. The observed ranking of binding interaction of the tested EDCs with ER-beta is diethylstilbestrol (DES) > 17-beta-estradiol > 17-alpha-estradiol > 2-OH-estrone > bisphenol A > p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) with measurements exhibiting intra-day RSDs of about 3%. A comparison of responses of three EDCs, which include 17-beta-estradiol, 17-alpha-estradiol, and 2-OH-estrone, with ER-beta and ER-alpha illustrates which estrogen receptor subtype provides the greatest sensitivity. Antibodies specific to a particular EDC can also be used for analyte specific screening. Calibration plots for a MC functionalized with anti-17-beta-estradiol Ab show responses in the range of 1 x 10(-11) through 1 x 10(-7) M for 17-beta-estradiol with a linear portion extending over two orders of magnitude in concentration.
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Affiliation(s)
- Pampa Dutta
- Department of Chemistry, University of Tennessee, 420 Buehler Hall, Knoxville, Tennessee 37996-1600, USA
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123
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Zhang R, Best A, Berger R, Cherian S, Lorenzoni S, Macis E, Raiteri R, Cain R. Multiwell micromechanical cantilever array reader for biotechnology. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2007; 78:084103. [PMID: 17764339 DOI: 10.1063/1.2775433] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
We use a multiwell micromechanical cantilever sensor (MCS) device to measure surface stress changes induced by specific adsorption of molecules. A multiplexed assay format facilitates the monitoring of the bending of 16 MCSs in parallel. The 16 MCSs are grouped within four separate wells. Each well can be addressed independently by different analyte liquids. This enables functionalization of MCS separately by flowing different solutions through each well. In addition, each well contains a fixed reference mirror which allows measuring the absolute bending of MCS. In addition, the mirror can be used to follow refractive index changes upon mixing of different solutions. The effect of the flow rate on the MCS bending change was found to be dependent on the absolute bending value of MCS. Experiments and finite element simulations of solution exchange in wells were performed. Both revealed that one solution can be exchanged by another one after 200 microl volume has flown through. Using this device, the adsorption of thiolated DNA molecules and 6-mercapto-1-hexanol on gold surfaces was performed to test the nanomechanical response of MCS.
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Affiliation(s)
- R Zhang
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128, Mainz, Germany
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124
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Butt HJ, Berger R, Bonaccurso E, Chen Y, Wang J. Impact of atomic force microscopy on interface and colloid science. Adv Colloid Interface Sci 2007; 133:91-104. [PMID: 17662682 DOI: 10.1016/j.cis.2007.06.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Revised: 06/06/2007] [Accepted: 06/06/2007] [Indexed: 11/17/2022]
Abstract
Since its invention twenty years ago the atomic force microscope (AFM) has become one of the most important tools in colloid and interface science. The reason for this impact is that the AFM allows doing experiments on length, time, force, and energy scales, which are not accessible by any other technique. These experiments can be carried out under natural conditions, for example in liquid environments. In this paper we specify the length and time scales involved, give examples where by using the AFM relevant questions in colloid and interface science have been solved, and we discuss future perspectives.
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Affiliation(s)
- H-J Butt
- Max Planck Institute for Polymer Research, Mainz, Germany.
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125
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Fragouli D, Kitsopoulos TN, Chiodo L, Della Sala F, Cingolani R, Ray SG, Naaman R. Imaging photoelectron transmission through self-assembled monolayers: the work-function of alkanethiols coated gold. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:6156-62. [PMID: 17441738 DOI: 10.1021/la063471t] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
In this paper, we present a new approach for studying the electronic properties of self-assembled monolayers and their interaction with a conductive substrate, the low-energy photoelectron imaging spectroscopy (LEPIS). LEPIS relies on imaging of photoelectrons ejected from a conductive substrate and subsequently transmitted through organic monolayers. Using this method, we measure the relative work-function of alkanethiols of different length on gold substrate, and we are able to follow the changes occurring when the surface coverage is varied. We also computed the work-function of model alkanethiols using a plane-wave density functional theory approach, in order to demonstrate the correlation between changes in the work-function with the monolayer organization and density.
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Affiliation(s)
- Despina Fragouli
- Institute of Electronic Structure and Laser (FORTH) and Department of Chemistry, University of Crete, 71110 Heraklion-Crete, Greece
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126
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Koeser J, Shahgaldian P, Bammerlin M, Battiston FM, Pieles U. Time Resolved Analysis of Molecular Interactions Using Nanomechanical Cantilever Sensors. ACTA ACUST UNITED AC 2007. [DOI: 10.1088/1742-6596/61/1/123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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127
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Zang J, Huang M, Liu F. Mechanism for nanotube formation from self-bending nanofilms driven by atomic-scale surface-stress imbalance. PHYSICAL REVIEW LETTERS 2007; 98:146102. [PMID: 17501292 DOI: 10.1103/physrevlett.98.146102] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2006] [Indexed: 05/13/2023]
Abstract
We demonstrate, by theoretical analysis and molecular dynamics simulation, a mechanism for fabricating nanotubes by self-bending of nanofilms under intrinsic surface-stress imbalance due to surface reconstruction. A freestanding Si nanofilm may spontaneously bend itself into a nanotube without external stress load, and a bilayer SiGe nanofilm may bend into a nanotube with Ge as the inner layer, opposite of the normal bending configuration defined by misfit strain. Such rolled-up nanotubes can accommodate a high level of strain, even beyond the magnitude of lattice mismatch, greatly modifying the tube electronic and optoelectronic properties.
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Affiliation(s)
- Ji Zang
- Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, USA
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128
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Beaulieu LY, Godin M, Laroche O, Tabard-Cossa V, Grütter P. A complete analysis of the laser beam deflection systems used in cantilever-based systems. Ultramicroscopy 2007; 107:422-30. [PMID: 17174033 DOI: 10.1016/j.ultramic.2006.11.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2006] [Revised: 11/02/2006] [Accepted: 11/02/2006] [Indexed: 10/23/2022]
Abstract
A working model has been developed which can be used to significantly increase the accuracy of cantilever deflection measurements using optical beam techniques (used in cantilever-based sensors and atomic force microscopes), while simultaneously simplifying their use. By using elementary geometric optics and standard vector analysis it is possible, without any fitted or adjustable parameters, to completely and accurately describe the relationship between the cantilever deflection and the signal measured by a position sensitive photo-detector. By arranging the geometry of the cantilever/optical beam, it is possible to tailor the detection system to make it more sensitive at different stages of the cantilever deflection or to simply linearize the relationship between the cantilever deflection and the measured detector signal. Supporting material and software has been made available for download at http://www.physics.mun.ca/beauliu_lab/papers/cantilever_analysis.htm so that the reader may take full advantage of the model presented herein with minimal effort.
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Affiliation(s)
- L Y Beaulieu
- Department of Physics and Physical Oceanography, Memorial University. St. John's, NL., Canada A1B 3X7
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129
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Subramanian S, Sampath S. Enhanced thermal stability and structural ordering in short chain n-alkanethiol monolayers on gold probed by vibrational spectroscopy and EQCM. Anal Bioanal Chem 2007; 388:135-45. [PMID: 17393151 DOI: 10.1007/s00216-007-1184-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2006] [Revised: 01/22/2007] [Accepted: 02/06/2007] [Indexed: 11/25/2022]
Abstract
Monolayers of alkanethiols with varied chain lengths, CH3(CH2)nSH where n=3, 5, and 7, on gold substrates have been prepared by adsorption from (1) neat thiol, (2) millimolar thiol solution in alcohol (conventional method), and (3) potential-controlled adsorption. Reflection absorption infrared spectroscopy (RAIRS) and electrochemical quartz crystal microbalance (EQCM) have been used to characterize the integrity of the monolayers. Methylene and methyl stretching modes along with C-S stretching modes have been used as benchmarks to follow the order-disorder transitions in the monolayer structure, in the temperature range from 25 to 175 degrees C. Monolayers adsorbed from neat thiol show superior quality in terms of stability and structural arrangement. Short chain thiols with n=3, 5, and 7 do show substantial stability. The possibility of multilayer formation is ruled out by EQCM studies comparing the frequency and mass change associated with the monolayer desorption. Self-assembled monolayers (SAMs) adsorbed under potential control behave very similarly to the monolayers adsorbed from neat thiol as far as stability and structural orientation are concerned, irrespective of the chain length. The adsorption from neat thiol gets rid of the solvent-induced defects and arrests the propagation of defects under temperature constraints.
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Affiliation(s)
- S Subramanian
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, 560 012, India
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130
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Bumbu GG, Wolkenhauer M, Kircher G, Gutmann JS, Berger R. Micromechanical cantilever technique: a tool for investigating the swelling of polymer brushes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:2203-7. [PMID: 17279715 DOI: 10.1021/la062137u] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Polymer brush coatings are well-known for their ability to tailor surface properties in a wide range of applications from colloid stabilization to medicine. In most cases, the brushes are used in solution. Consequently, efforts were expended to experimentally investigate or theoretically predict the swelling behavior of the brushes in solvents of different qualities. Here, we show that the micromechanical cantilever (MC) sensor technique is a tool to perform time-resolved physicochemical investigations of thin layers such as polymer brushes. Complementary to scattering techniques, which measure the thickness, the MC sensor technique provides information about changes in the internal pressure of the brushes during a swelling and deswelling process. We show that the kinetics of both swelling and deswelling are dependent on solvent quality. Comparing the measured data with its thickness evolution, which was calculated based on the Flory-Huggins theory, we found that only the first 10% of the thickness increase of the polymer brush results in a significant pressure increase inside the polymer brush layer.
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Affiliation(s)
- Gina-Gabriela Bumbu
- Max Planck Institute for Polymer Research, Ackermannweg 10, D 55128 Mainz, Germany
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131
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Pera I, Fritz J. Sensing lipid bilayer formation and expansion with a microfabricated cantilever array. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:1543-7. [PMID: 17241085 DOI: 10.1021/la0624337] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We show that cantilever array sensors can sense the formation of supported phospholipid bilayers on their surface and that they can monitor changes in mechanical properties of lipid bilayers. Supported lipid bilayers were formed on top of microfabricated cantilevers by vesicle fusion. The formation of bilayers led to a bending of the cantilevers of 70-590 nm comparable to a surface stress of 27-224 mN/m. Physisorption of bilayers of DOPC and other bilayers on the silicon oxide surface of cantilevers led to a tensile bending of about 70 nm whereas formation of chemisorbed bilayers of mixed thiolated (DPPTE) and non-thiolated lipids (DOPC) on the gold side of cantilevers led to a compressive bending of nearly 600 nm which depended on the ratio of DPPTE to DOPC. First results on bending of bilayer-covered cantilevers due to their interaction with the pore-forming peptide melittin are shown. The results demonstrate that cantilever sensors with immobilized bilayers can be used as model systems to investigate mechanical properties of cellular membranes and may be used for screening of membrane processes involving modification, lateral expansion, or contraction of membranes.
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Affiliation(s)
- Ioana Pera
- School of Engineering and Science, International University Bremen, Campus Ring 1, 28759 Bremen, Germany
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132
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Wang C, Wang D, Mao Y, Hu X. Ultrasensitive biochemical sensors based on microcantilevers of atomic force microscope. Anal Biochem 2007; 363:1-11. [PMID: 17276384 DOI: 10.1016/j.ab.2006.12.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2006] [Revised: 11/23/2006] [Accepted: 12/05/2006] [Indexed: 11/21/2022]
Affiliation(s)
- Chengyin Wang
- College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, China
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133
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Quist A, Chand A, Ramachandran S, Cohen D, Lal R. Piezoresistive cantilever based nanoflow and viscosity sensor for microchannels. LAB ON A CHIP 2006; 6:1450-4. [PMID: 17066169 DOI: 10.1039/b604842k] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Microfluidic channels are microreactors with a wide range of applications, including molecular separations based upon micro/nanoscale physicochemical properties, targeting and delivery of small amount of fluids and molecules, and patterned/directed growth. Their successful applications would require a detailed understanding of phenomena associated with the microscale flow of liquids through these channels, including velocity, viscosity and miscibility. Here we demonstrate a highly sensitive piezoresistive cantilever to measure flow properties in microfluidic channels. By milling down the legs of the piezoresistive cantilevers, we have achieved significantly higher mechanical sensitivity and a smaller spring constant, as determined by AFM. These cantilevers were used in microchannels to measure the viscosity and flow rate of ethylene glycol mixtures in water over a range of concentrations, as well as of low viscosity biologically relevant buffers with different serum levels. The sensor can be used alone or can be integrated in AFM systems for multidimensional study in micro and nanochannels.
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Affiliation(s)
- Arjan Quist
- Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA 93106, USA.
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134
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Zuo G, Li X, Li P, Yang T, Wang Y, Cheng Z, Feng S. Detection of trace organophosphorus vapor with a self-assembled bilayer functionalized SiO2 microcantilever piezoresistive sensor. Anal Chim Acta 2006; 580:123-7. [PMID: 17723763 DOI: 10.1016/j.aca.2006.07.071] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2006] [Revised: 07/21/2006] [Accepted: 07/22/2006] [Indexed: 11/30/2022]
Abstract
Using piezoresistive SiO2 microcantilever technology, we present an ultra-sensitive chemical sensor for trace organophosphorus vapor detection. A self-assembled composite layer of Cu2+/11-mercaptoundecanoic acid is modified on the surface of the sensing cantilever as a specific coating to capture P=O containing compounds. Experimental results indicate that the sensor can be quite sensitive to DMMP vapor (well known as a simulant of nerve agent). The signal-noise-limited detection resolution of the sensor is experimentally obtained as low as several parts per billion. Besides that the sensor can yield reversible and repeatable response to DMMP vapor, adsorption of DMMP on the self-assembled composite layer is well fit to the Langmuir isotherm model.
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Affiliation(s)
- Guomin Zuo
- State Key Lab of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, China
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135
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Xie R, He TJ, He L, Chen DM, Liu FC. DFT Study on the Intermolecular Substrate-mediated Interaction Energy in the Self-assembly of Alkanethiols on Silver. CHINESE J CHEM PHYS 2006. [DOI: 10.1360/cjcp2006.19(5).406.5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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136
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Desikan R, Lee I, Thundat T. Effect of nanometer surface morphology on surface stress and adsorption kinetics of alkanethiol self-assembled monolayers. Ultramicroscopy 2006; 106:795-9. [PMID: 16678968 DOI: 10.1016/j.ultramic.2005.11.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2005] [Accepted: 11/06/2005] [Indexed: 10/24/2022]
Abstract
Microcantilevers undergo quasi-static bending due to adsorption-induced stress when adsorption is confined to a single surface. Understanding the origin of surface stress is crucial for optimizing sensor performance. We have investigated the effect of surface morphology of gold-coated cantilevers on the adsorption characteristics of self-assembled monolayers of alkanethiols. Self-assembly of alkanethiols from liquid phase closely follows Langmuir-type kinetics up to a single monolayer assembly. Our results indicate that alkanethiol adsorption-induced surface stress is largely unaffected by surface roughness of the cantilever. Unlike prior reports that suggest surface roughness enhances adsorption-induced stress, we observe that nanometer-size roughness slightly decreases surface stress and adsorption kinetics.
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Affiliation(s)
- Ramya Desikan
- Physics Department, University of Tennessee, Knoxville, 37996-1200, USA
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137
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Amritsar J, Stiharu I, Packirisamy M. Bioenzymatic detection of troponin C using micro-opto-electro-mechanical systems. JOURNAL OF BIOMEDICAL OPTICS 2006; 11:021010. [PMID: 16674185 DOI: 10.1117/1.2186326] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Diagnosis and monitoring of critical diseases such as acute myocardial infarction (AMI) require a quantitative analysis of biological molecules. A high-throughput identification of these biological molecules can be generated by using micro-electro-mechanical systems (MEMS) structures like simple cantilever beams, which respond to the intermolecular forces resulting from binding these molecules. Biochemical markers like troponin C are considered the primary markers for myocardial injury and have generated considerable interest. A 26-residue lytic membrane protein of bee venom melittin (ME) is chosen to interact with rabbit skeletal muscle troponin C (TnC) on the surface of the cantilever beams. An optical beam deflection method is employed to identify the enzymatic reaction on the surface of the cantilever due to these proteins. Identification of these proteins is also done using fluorescence spectroscopy (FS) to compliment the optical monitored deflection method. A second set of proteins like horse radish peroxide (HRP) and hydrogen peroxide (H2O2) are applied to atomic force microscopy (AFM) cantilever beams to study their behavior under the enzymatic reactions of proteins. Identification of these proteins is done using Fourier transform infrared spectroscopy (FTIR). An analytical model of the cantilever beam is developed, and its mode shapes are studied by employing orthogonal polynomials in the classic Rayleigh-Ritz method. The surface stress caused by the enzymatic reaction of the proteins that leads to pure bending on the top surface of the cantilever is evaluated. The information provided by the experimental and analytical modeling reported in this work will be useful in the development of a portable biosensor for the detection of AMI.
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Affiliation(s)
- Jeetender Amritsar
- Concordia University, Micromechatronics Laboratory, Concave Research Center, 1455 de Maisonneuve Boulevard, Montreal, Quebec H3G 1M8 Canada.
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138
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139
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Surface stress of polyelectrolyte adsorption measured by micromechanical cantilever sensors. E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY 2006. [DOI: 10.1380/ejssnt.2006.96] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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140
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Zhou F, Huck WTS. Surface grafted polymer brushes as ideal building blocks for “smart” surfaces. Phys Chem Chem Phys 2006; 8:3815-23. [DOI: 10.1039/b606415a] [Citation(s) in RCA: 249] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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141
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Fabrication of piezoresistive microcantilever using surface micromachining technique for biosensors. Ultramicroscopy 2005. [DOI: 10.1016/j.ultramic.2005.06.040] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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142
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Law M, Zhang XF, Yu R, Kuykendall T, Yang P. Thermally driven interfacial dynamics of metal/oxide bilayer nanoribbons. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2005; 1:858-65. [PMID: 17193540 DOI: 10.1002/smll.200500114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Solid-solid interfacial processes greatly affect the performance of electronic and composite materials, but probing the dynamics of buried interfaces is challenging and often involves lengthy or invasive sample preparation. We show that bilayer nanoribbons-made here of tin dioxide and copper-are convenient structures for observing as-made interfaces as they respond to changing temperature in a transmission electron microscope (TEM). At low temperatures (<200 degrees C), differential thermal expansion causes the bilayers to bend when heated or cooled, with the motion determined by the extent of Cu-SnO(2) epitaxy. At higher temperatures, we are able to watch-in real time and with nanometer resolution-a progression of grain growth, interdiffusion, island formation, solid-state chemical reactions, and melting. This novel TEM geometry is readily applicable to other nanoribbon/coating combinations and is well suited to observing interfacial phenomena driven thermally or by the application of mechanical, electrical, or magnetic forces.
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Affiliation(s)
- Matt Law
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, USA
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143
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Wee KW, Kang GY, Park J, Kang JY, Yoon DS, Park JH, Kim TS. Novel electrical detection of label-free disease marker proteins using piezoresistive self-sensing micro-cantilevers. Biosens Bioelectron 2005; 20:1932-8. [PMID: 15741060 DOI: 10.1016/j.bios.2004.09.023] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2004] [Revised: 08/25/2004] [Accepted: 09/20/2004] [Indexed: 11/26/2022]
Abstract
We report an electro-mechanical biosensor for electrical detection of proteins with disease markers using self-sensing piezoresistive micro-cantilevers. Electrical detection, via surface stress changes, of antigen-antibody (Ag-Ab) specific binding was accomplished through a direct nano-mechanical response of micro-fabricated self-sensing micro-cantilevers. A piezoresistive sensor measures the film resistance variation with respect to surface stress caused by biomolecules specific binding. When specific binding occurred on a functionalized Au surface, surface stress was induced throughout the cantilever, resulting in cantilever bending and resistance change of the piezoresistive layer. The cantilever biosensors were used for the detection of prostate specific antigen (PSA) and C-reactive proteins (CRP), which are a specific marker of prostate cancer and cardiac disease. From the above experiment, it was revealed that the sensor output voltage was proportional to the injected antigen concentration (without antigen, 10 ng/ml, 100 ng/ml, 1 microg/ml). PSA and CRP antibodies were found to be very specific for their antigens, respectively. This indicated that the self-sensing micro-cantilever approach is beneficial for detecting disease markers, and our piezoresistive micro-cantilever sensor system is applicable to miniaturized biosensor systems.
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Affiliation(s)
- Kyung Wook Wee
- Microsystem Research Center, Korea Institute of Science and Technology (KIST), Seoul 136-791, Republic of Korea
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144
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Lee JH, Hwang KS, Park J, Yoon KH, Yoon DS, Kim TS. Immunoassay of prostate-specific antigen (PSA) using resonant frequency shift of piezoelectric nanomechanical microcantilever. Biosens Bioelectron 2005; 20:2157-62. [PMID: 15741091 DOI: 10.1016/j.bios.2004.09.024] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2004] [Revised: 09/27/2004] [Accepted: 09/28/2004] [Indexed: 11/26/2022]
Abstract
We designed and fabricated the nanomechanical Pb(Zr0.52Ti0.48)O3 (PZT) cantilever; we demonstrated a novel electrical measurement, under a controlled ambient temperature and humidity, for label-free detection of a prostate-specific antigen (PSA); and we achieved a detection sensitivity as low as 10 pg/ml. For the fabrication of our nanomechanical PZT cantilevers, we used composite layers of Ta/Pt/PZT/Pt/SiO2 on a SiN(x) supporting layer for electrical self-sensing without external oscillators. This method allows PSA proteins to be detected via a simple electrical measurement of the resonant frequency change generated by the molecular interaction of the antigen (Ag) and the antibody (Ab). The resonant frequency shifted due to the specific binding of the PSA Ag to its Ab which is immobilized via calixcrown self-assembled monolayers on an Au surface deposited on a nanomechanical PZT cantilever. We determined the resonant frequency shift as the value of -172 Hz and -273 Hz, when the concentration of PSA Ag was 1 ng/ml, with the cantilever dimensions of 100 microm x 300 microm and 50 microm x 150 microm, respectively. Theoretical and experimental analysis suggests that the minimum detectable sensitivity for a resonant frequency shift due to a PSA Ag-Ab interaction depends on the dimensions of the nanomechanical PZT cantilever. These results also demonstrate that the experimentally measured resonant frequency shift is larger than that calculated theoretically due to the compressive stress of the PSA Ag-Ab interaction.
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145
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Lüthgens E, Janshoff A. Equilibrium Coverage Fluctuations: A New Approach to Quantify Reversible Adsorption of Proteins. Chemphyschem 2005; 6:444-8. [PMID: 15799468 DOI: 10.1002/cphc.200400446] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Eike Lüthgens
- Institute of Physical Chemistry, University of Mainz, Welder Weg 11, 55128 Mainz, Germany
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146
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Bonaccurso E, Gillies G. Revealing contamination on AFM cantilevers by microdrops and microbubbles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:11824-11827. [PMID: 15595819 DOI: 10.1021/la047978k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Affiliation(s)
- Elmar Bonaccurso
- Max-Planck-Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
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147
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Lee JH, Yoon KH, Hwang KS, Park J, Ahn S, Kim TS. Label free novel electrical detection using micromachined PZT monolithic thin film cantilever for the detection of C-reactive protein. Biosens Bioelectron 2004; 20:269-75. [PMID: 15308231 DOI: 10.1016/j.bios.2004.01.024] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2003] [Revised: 01/20/2004] [Accepted: 01/22/2004] [Indexed: 10/26/2022]
Abstract
In this paper, we report the novel electrical measurement for the label-free detection of C-reactive protein (CRP) using resonant frequency shift in the monolithic thin film cantilever of micromachined Pb(Zr0.52Ti0.48)O3 (PZT) which was fabricated with the composition of SiO2/Ta/Pt/PZT/Pt/SiO2 on silicon nitride (SiNx) supporting layer for the dual purpose of electrical self-excitation and sensing. The specific binding characteristics of CRP antigen to its antibody, which is immobilized with Calixcrown SAMs on Au surface deposited on microcantilever, is determined in high sensitivity to the nanogram level per milliliter by measuring the resonant frequency shift. The nanomechanical PZT cantilever turns out a robust platform for the highly specific antigen-antibody interaction and provides with the novel tool for qualification and quantification of biomolecules without any sample labeling and bulky optical apparatus.
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Affiliation(s)
- Jeong Hoon Lee
- Microsystem Research Center, 39-1 Haweolgok-dong, Seongbuk-gu, KIST, Seoul 136-791, South Korea
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148
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Tian F, Pei JH, Hedden DL, Brown GM, Thundat T. Observation of the surface stress induced in microcantilevers by electrochemical redox processes. Ultramicroscopy 2004; 100:217-23. [PMID: 15231313 DOI: 10.1016/j.ultramic.2003.12.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2003] [Revised: 11/24/2003] [Accepted: 12/02/2003] [Indexed: 10/26/2022]
Abstract
The potential-induced surface stress of a solid electrode was investigated in an electrochemical cell. Gold-coated atomic force microscopy microcantilevers were used as working electrodes to measure the current-potential response (by cyclic voltammetry) and simultaneous bending characteristics in solutions of NaNO3 and K3Fe(CN)6/NaNO3. The observed changes of differential surface stress at a microcantilever electrode were attributed to electrochemical-potential-induced changes in surface charge density, ion adsorption/desorption, and electron transfer across the electrode surface. The potential dependent change in stress shows promise for the study of microscopic properties at the solid-electrolyte interface.
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Affiliation(s)
- F Tian
- Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6123, USA
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149
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Godin M, Williams PJ, Tabard-Cossa V, Laroche O, Beaulieu LY, Lennox RB, Grütter P. Surface stress, kinetics, and structure of alkanethiol self-assembled monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:7090-7096. [PMID: 15301492 DOI: 10.1021/la030257l] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The surface stress induced during the formation of alkanethiol self-assembled monolayers (SAMs) on gold from the vapor phase was measured using a micromechanical cantilever-based chemical sensor. Simultaneous in situ thickness measurements were carried out using ellipsometry. Ex situ scanning tunneling microscopy was performed in air to ascertain the final monolayer structure. The evolution of the surface stress induced during coverage-dependent structural phase transitions reveals features not apparent in average ellipsometric thickness measurements. These results show that both the kinetics of SAM formation and the resulting SAM structure are strongly influenced both by the surface structure of the underlying gold substrate and by the impingement rate of the alkanethiol onto the gold surface. In particular, the adsorption onto gold surfaces having large, flat grains produces high-quality self-assembled monolayers. An induced compressive surface stress of 15.9 +/- 0.6 N/m results when a c(4x2) dodecanethiol SAM forms on gold. However, the SAMs formed on small-grained gold are incomplete and an induced surface stress of only 0.51 +/- 0.02 N/m results. The progression to a fully formed SAM whose alkyl chains adopt a vertical (standing-up) orientation is clearly inhibited in the case of a small-grained gold substrate and is promoted in the case of a large-grained gold substrate.
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Affiliation(s)
- Michel Godin
- Department of Physics, McGill University, Montreal, Quebec, Canada H3A 2T8.
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150
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Camillone N. Diffusion-limited thiol adsorption on the gold(111) surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:1199-206. [PMID: 15803697 DOI: 10.1021/la030121n] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
An optical second harmonic generation measurement of the kinetics of self-assembly of a monolayer of thiols on the Au(111) surface reveals a marked dependence of the adsorption rate upon the solution flow rate. The nature of this dependence indicates that at low concentration and low flow rate the monolayer growth is limited by the existence of a Nernst diffusion layer, not by surface reaction rate kinetics.
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Affiliation(s)
- Nicholas Camillone
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
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