Chemiresistor Sensors Based on Gold Nanoparticle Composites - Core

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aInstitute of Electronic and Sensor Materials, Technische Universität ... detecting of extremely small concentrations of analytes (few parts per billion), have been.
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ScienceDirect Procedia Engineering 120 (2015) 799 – 802

EUROSENSORS 2015

Chemiresistor sensors based on gold nanoparticle composites Y. Daskala, R. Dittricha, J. Walterb, Y. Josepha* a

Institute of Electronic and Sensor Materials, Technische Universität Bergakademie Freiberg, Gustav-Zeuner Str., 3, Freiberg 09599, Germany b Institute for Experimental Physics, Technische Universität Bergakademie Freiberg, Leipziger Str., 23, Freiberg 09599, Germany

Abstract On a silicon wafer equipped with interdigital electrodes, gold nanoparticles with an average size of 5 nm are assembled in a thin film using different organic linkers, either manually by layer-by-layer spin coating or automatically by layer-by-layer selfassembly in a microfluidic cell. The composition of the films is analyzed by X-ray photoelectron spectroscopy (XPS). The electrical and chemiresistive sorption properties of toluene, 1-propanol, 4-methyl-2-pentanone and water in the organic/nanoparticles composites are investigated. © by Elsevier Ltd. This an open Ltd. access article under the CC BY-NC-ND license © 2015 2015Published The Authors. Published by isElsevier (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-reviewunder under responsibility the organizing committee of EUROSENSORS 2015. Peer-review responsibility of theoforganizing committee of EUROSENSORS 2015

Keywords: gold nanoparticles; spin coater; quarz crystal microbalance; chemiresistor; sensor.

1. Introduction During the past decades, gold nanoparticles become one of the most relevant topics for scientists [1]. Gold nanoparticles have attracted such considerable interest due to their potential applications in catalysis, bio-labeling, and photonics. Their size, size distribution, and morphology control become the key to the understanding of the optical and surface properties [2, 3]. Due to their unique optoelectronic properties, high surface-to-volume ratio and excellent biocompatibility, gold nanoparticles allow researchers to develop the novel sensing strategies with improved sensitivity, stability and selectivity [4]. According to their tiny sizes (up to 100 nm), new types of nanosensors, which allow detecting of extremely small concentrations of analytes (few parts per billion), have been developed. Several research groups have demonstrated that these films can be used for numerous applications, such as vapor or gas sensors [5-10]. From the other hand, gold nanoparticles are also very suitable for selective coatings

* Corresponding author. Tel.: +49 -373-1 39-2146; fax: +49-373-139-3662. E-mail address: [email protected]

1877-7058 © 2015 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

(http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of EUROSENSORS 2015

doi:10.1016/j.proeng.2015.08.828

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for strain gauges [11, 12], electrochemical sensors [13, 14], and substrates for surface enhanced Raman scattering (SERS) [15]. In this work, we report on the assembly, the material conductivity, the chemical composition, and the vapor response of the nanoparticle networks interlinked with aromatic, conductive organic molecules. For the films manufacturing, two methods were implemented: manual layer-by-layer preparation with a spin coater and automatic layer-by-layer self-assembly in a microfluidic cell. Additionally, systematic investigations how the molecular structure and composition of oligophenyldithiol-interlinked films depend on the nature of the linker molecule and method of film preparation are performed. 2. Materials and samples preparation Chemicals were purchased from Sigma Aldrich, Merck, VWR, Technic France, and Honeywell and used as received. 1,4-Benzenedithiol, 1,4-Benzenedimethanethiol, Biphenyl-4,4′-dithiol, and p-Terphenyl-4,4′′-dithiol linkers were used as the organic linker molecules (0.5 mmol/L in toluene). For the substrates surface functionalization, 3-Mercaptopropyltriethoxysilane (MPTES) and Aminopropyldimethyl-ethoxysilane (APDMES) were used as silanization agents. The gold nanoparticles (AuNP) were synthesized, as was described by Peng [16], at 20̊ C. A silicon wafer with a defined thickness of 625±15 μm, obtained through Siltronic AG, was cut to the small pieces with an edge length ca. 15 mm and used as substrates for all measurements. For the sensing measurements, the substrates were equipped with gold finger-electrodes (52 finger pairs, 50 μm width and 5.2 mm length, 100μm gap). The method of manual preparation of the samples was proposed by Schlicke et al. [17] and used in a modified way, as reported in [18]. The method of automatic layer-by-layer self-assembling was previously described by D. Bethell and co-workers [19]. Firstly, the silicon substrates were cleaned with DI-water and isopropanol and left in the linker solution over the night. Prior to the films deposition, the substrates surfaces were functionalized via gas phase silanisation. Then the substrates were placed to the microfluidic cell, treated for 5 minutes with nanoparticles solution, then washed for 4 minutes with toluene, treated for 5 minutes with linker solution again, and once more washed with toluene (1 deposition cycle). These steps were repeated 15 times. Afterwards, the films were washed with toluene and drying with air for 10 minutes respectively. After the preparation, all samples were placed in a desiccator under argon atmosphere. 3. Results and discussions 3.1 X-Ray Photoelectron Spectroscopy (XPS) The composition of all films was studied with XPS. Au, C and S were found. During the layer-by-layer preparation of the films, the stabilizing molecules (dodecylamine) of the nanoparticles were completely exchanged by the interlinking molecules. That was indicated by an absence of a peak from nitrogen. As shown in Fig. 1, the number of free thiols in the samples interlinked with 1,4-Benzenedithiol, 1,4-Benzenedimethanethiol, Biphenyl-4,4′dithiol, and p-Terphenyl-4,4′′-dithiol remains higher than the sulphur-to-gold bonds. In the other words, most of the dithiols are bounded only with one end to the gold nanoparticle or are intercalated in the organic matrix instead of being covalent attached to the nanoparticles. The reason for that might be comparative small length of linker molecules and wide distribution of gold nanoparticles. For the sample interlinked with 1,4-Benzenedimethanethiol, the number of free thiols is smaller than sulphur-gold bonds, because of the presence of the aliphatic group in the linker, which makes interlinkage more flexible. In the case of preparation with the microfluidic cell, no oxidation peaks were found, and the level of interlinkage in samples was higher. Thus the automated layer-by-layer preparation with the microfluidic cell is favoured over the manually spin coating process. 3.2 Sensing Properties The sorption of toluene, 1-propanol, 4-methyl-2-pentanone, and water in the organic molecules-nanoparticles composites was investigated by coating the material on substrates equipped with interdigitated electrodes. The similar vapor pressure of solvents makes them very suitable for studying the chemical selectivity of the sensor materials [4]. For all analytes, concentration dependent measurements of the mass in the range 100 – 5000 ppm were performed. The response traces toward 5000ppm of the analytes are given in Fig. 2.

Y. Daskal et al. / Procedia Engineering 120 (2015) 799 – 802

Fig. 1. S2p spectra. The degree of interlinkage, represented by the S-Au/S-H ratio is indicated

Fig. 2. Sensor responses. Concentration 5000 ppm. Preparation with microfluidic cell.

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The low level of interlinkage and corresponding high sorption capacity cause relatively high sensitivity of the samples prepared by level-by-level self-assembly. Increasing of resistance during the experiments i.e. positive electrical signal is connected with phenomena of film’s swelling. Decreasing of resistance in the samples 2-4 during the experiments i.e. negative electrical signal can be explained by phenomena of pore filling. With growing of the linker length, an increase in the pore filling effect is observed, while swelling became minor. The selectivity of the analytes uptake of the films is comparable for all materials, as expected due to the similar chemistry of the linker molecules. In the case of the samples prepared with spin coater, the responses are smaller, slower and not fully reversible. This may be due to the oxidized nature of the film or the enhanced swelling probability due to a lower degree of interlinkage. 4. Conclusions The possibility of fast response, reversibility and the high sensitivity to volatile organic compounds (VOCs) make noble metal nanoparticle composite films promising materials for sensor applications. Concerning the fabrication the automated layer-by-layer preparation with the microfluidic cell is favoured over the manually spin coating process. References [1] M.-C. Daniel and D. Astruc, Gold Nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology, Chem. Rev. 104 (2004) 293−346. [2] X. Huang, M. A. El-Sayed, Gold nanoparticles: optical properties and implementations in cancer diagnosis and photothermal terapy, J. Adv. Res. 1 (2010) 13–28. [3] K. Saha, S. S. Agasti, C. Kim, X. Li, V. M. Rotello , Gold nanoparticles in chemical and biological sensing, Chem Rev. 9 (2012) 2739-79. [4] Y. Joseph, I. Besnard, M. Rosenberger, B. Guse, H.-G. Nothofer, J. M. Wessels, U. Wild, A. Knop-Gericke, D. Su, R. Schlögl, A. Yasuda, and T. Vossmeyer, Self-assembled gold nanoparticle/alkanedithiol films: preparation, electron microscopy, XPS-analysis, charge transport and vapor-sensing properties, J. Phys. Chem. B 107 (2003) 7406-7413. [5] L. Wang, X. Shi, N. N. Kariuki, M. Schadt, G. R. Wang, Q. Rendeng, J. Choi, J. Luo, S. Lu, C.-J. Zhong, Array of molecularly mediated thin film assemblies of nanoparticles: correlation of vapor sensing with interparticle spatial properties, J. Am. Chem. Soc. 129 (2007) 2161-2170. [6] F. P. Zamborini, M. C. Leopold, J. F. Hicks, P. J. Kulesza, M. A. Malik, R. W. Murray, Electron hopping conductivity and vapor sensing properties of flexible network polymer films of metal nanoparticles, J. Am. Chem. Soc. 124 (2002) 8958–8964. [7] Y. Joseph, B. Guse, T. Vossmeyer, Chemiresistor coatings from Pt- and Au-nanoparticle/nonanedithiol films: sensitivity to gases and solvent vapors, Sensor Actuat. B-Chem. 98 (2004) 188-195. [8] Y. Joseph, A. Peić, X. Chen, J. Michl, T. Vossmeyer, A. Yasuda, Vapor sensitivity of networked gold nanoparticle chemiresistors:  importance of flexibility and resistivity of the interlinkage, J. Phys. Chem. C, 111 (2007) 12855–12859. [9] N. Krasteva, Y. Fogel, R. E. Bauer, K. Müllen, Y. Joseph, N. Matsuzawa, A. Yasuda, T. Vossmeyer, Cover picture: vapor sorption and electrical response of Au-nanoparticle– dendrimer composites, Adv. Funct. Mater. 17 (2007) 881-888. [10] H. Haick, D. Cahen, Making contact: connecting molecules electrically to the macroscopic world, Prog. Surf. Sci. 83 (2008) 217-261. [11] J. Herrmann, K.-H. Müller, T. Reda, G. R. Baxter, B. Raguse, G. J. J. B. De Groot, R. Chai, M. Roberts, L. Wieczorek, Nanoparticle films as sensitive strain gauges, Appl. Phys. Lett. 91 (2007) 183105-1-183105-3. [12] T. Vossmeyer, C. Stolte, M. Ijeh, A. Kornowski, H. Weller, Networked gold-nanoparticle coatings on polyethylene: charge transport and strain sensitivity, Adv. Funct. Mater. 18 (2008) 1611-1616. [13] A. N. Shipway, M. Lahav, R. Blonder, I. Willner, Bis-bipyridinium cyclophane receptor−Au nanoparticle superstructures for electrochemical sensing applications, Chem. Mater. 11 (1999) 13-15. [14] A. N. Shipway, E. Katz, I. Willner, Nanoparticle arrays on surfaces for electronic, optical, and sensor applications, Chemphyschem. 1 (2000) 18-52. [15] M. D. Musick, C. D. Keating, L. A. Lyon, S.L. Botsko, D. J. Peña, W. D. Holliway, T. M. McEvoy, J. N. Richardson, M. J. Natan, Metal films prepared by stepwise assembly. 2. Construction and characterization of colloidal Au and Ag multilayers, Chem. Mater. 12 (2000) 28692881. [16] S. Peng, Y. Lee, C. Wang, H. Yin, S. Dai, S. Sun, A facile synthesis of monodisperse Au nanoparticles and their catalysis of CO oxidation, Nano research, 9 (2008) 229-234. [17] H. Schlicke, J. H. Schröder, M. Trebbin, A. Petrov, M. Ijeh, H. Weller, T. Vossmeyer, Freestanding films of crosslinked gold nanoparticles prepared via layer-by-layer spin-coating, Nanotechnology, 22 (2011). [18] Y. Daskal, R. Dittrich, C. Himcinschi, B. Abendroth, J. Walter, Y. Joseph, Novel gold nanoparticle organic composites: characterization of optical and sensing properties, In: Proceedings – AMA Conferences, (2015) 267-272. [19] D. Bethell, M. Brust, D.J. Schiffrin, C. Kiely, From monolayers to nanostructured materials: an organic chemist's view of self-assembly, J. Electroanal. Chem. 409 (1996) 137-143.