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Pd-Doped Tin-Oxide-Based Thick-Film sensor array for Detection of H₂, CH₄, and CO

JOURNAL OF ELECTRONIC MATERIALS 2013年第9期42卷 2793-2802页

作者： Choudhary, Meenakshi Mishra, V. N. Dwivedi, R. Banaras Hindu Univ Indian Inst Technol Dept Elect Engn Ctr Res Microelect CRME Varanasi 221005 Uttar Pradesh India

In the present work, a palladium (Pd)-doped tin oxide (SnO2) thick-film sensor array has been developed by using solid state reaction-derived pure SnO2 powders (starting with two initial tin precursors: SnCl2 center dot 2H(2)O and SnCl4 center dot 5H(2)O). The crystal structure of the powders and the morphology of the thick films have been characterized by using x-ray diffraction and field-emission scanning electron microscopy, respectively. Initially, the sensitivity of all the sensors of the array was studied for hydrogen (H-2), methane (CH4), and carbon monoxide gas, followed by detailed analysis of the transient response of a 1 wt.% Pd-doped SnO2 sensor prepared by using SnCl4 center dot 5H(2)O as a starting tin precursor, as it possessed better sensitivity for all the test gases. It is found that this sensor exhibits fast response and recovery times (1 min and 3.05 min) along with good repeatability for test gases;however, for CH4 gas, it shows very much longer response and recovery times. The high response towards H-2 gas has been correlated well with the smallest crystallite size (18 nm) as well as the porous structure of the thick-film surface.

关键词： Thick film sensor array tin oxide palladium

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Paper-based fluorescence sensor array with functionalized carbon quantum dots for bacterial discrimination using a machine learning algorithm

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ANALYTICAL AND BIOANALYTICAL CHEMISTRY 2024年第13期416卷 3139-3148页

作者： Wang, Fangbin Xiao, Minghui Qi, Jing Zhu, Liang Hefei Univ Technol Sch Food & Biol Engn Hefei 230009 Peoples R China Natl Univ Singapore Dept Chem Singapore 117543 Singapore Hong Kong Polytech Univ Dept Biomed Engn Hong Kong 999077 Peoples R China

The rapid discrimination of bacteria is currently an emerging trend in the fields of food safety, medical detection, and environmental observation. Traditional methods often require lengthy culturing processes, specialized analytical equipment, and bacterial recognition receptors. In response to this need, we have developed a paper-based fluorescence sensor array platform for identifying different bacteria. The sensor array is based on three unique carbon quantum dots (CQDs) as sensing units, each modified with a different antibiotic (polymyxin B, ampicillin, and gentamicin). These antibiotic-modified CQDs can aggregate on the bacterial surface, triggering aggregation-induced fluorescence quenching. The sensor array exhibits varying fluorescent responses to different bacterial species. To achieve low-cost and portable detection, CQDs were formulated into fluorescent ink and used with an inkjet printer to manufacture paper-based sensor arrays. A smartphone was used to collect the responses generated by the bacteria and platform. Diverse machine learning algorithms were utilized to discriminate bacterial types. Our findings showcase the platform's remarkable capability to differentiate among five bacterial strains, within a detection range spanning from 1.0 x 103 CFU/mL to 1.0 x 107 CFU/mL. Its practicality is further validated through the accurate identification of blind bacterial samples. With its cost-effectiveness, ease of fabrication, and high degree of integration, this platform holds significant promise for on-site detection of diverse bacteria.

关键词： Bacterial discrimination sensor array CQDs Machine learning

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Dual-Channel Ratiometric Colorimetric sensor array for Quantification and Discrimination of o-, m-, and p-Phenols

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FOOD ANALYTICAL METHODS 2023年第1期16卷 96-106页

作者： Lan, Chengwu Meng, Lei Xu, Na Jilin Inst Chem Technol Coll Mat Sci & Engn Jilin 132022 Jilin Peoples R China

The determination of trace o-, m-, and p-phenols in food samples was of great significance, but it is still very challenging due to the low concertation and complex matrix. In comparison to traditional sensors based on the "lock-and-key" strategy, the sensor arrays that mimicked the human olfactory system exhibited excellent universality and efficiency in assays of structural analogs. Herein, we described a costless and robust colorimetric sensor array for quantification and discrimination of o-, m-, and p-phenols. The obtained Cu-2(OH)(3)Cl and Ni-doped Cu-2(OH)(3)Cl with peroxidase-like (POD) activity were served as nanozymes to accelerate the oxidation of 3,3 ',5,5 '-tetramethylbenzidine (TMB) with H2O2. UV-vis absorbance spectroscopy displayed remarkable enhancements both at 652 nm and 450 nm, individually attributable to the formation of single and dual electron-oxidized TMB (TMBox) substances. Then varied phenols regulated the absorbance via specific electron transfer processes. With the two peaks as dual signals, a ratiometric colorimetric sensor array based on nanozymes (i.e., Cu-2(OH)(3)Cl and Ni-doped Cu-2(OH)(3)Cl) was designed to monitor different phenols. The ratio (I-652/I-450) was recorded to quantify phenols sensitively, where internal reference ruled out interferences from the environment and equipment. Moreover, this array was also explored for simultaneous discrimination of o-, m-, and p-phenols. By integrating with colorimetric fingerprints and principal component analysis (PCA), each kind of phenol can be distinctly discriminated even at a very low concentration. This work demonstrated the reliability of a ratiometric sensor array for the recognition of multiple phenols.

关键词： sensor array Ratiometric Colorimetric Phenols Peroxidase Cu-2(OH)(3)Cl

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Novel sensor array based on doped tin oxide nanowires for organic vapor detection

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sensorS AND ACTUATORS B-CHEMICAL 2012年第1期162卷 251-258页

作者： Li, Xiaopeng Cho, Jung Hwan Kurup, Pradeep Gu, Zhiyong Univ Massachusetts Dept Chem Engn Lowell MA 01854 USA Univ Massachusetts Dept Civil & Environm Engn Lowell MA 01854 USA

A novel sensor array consisting of four types of doped tin oxide nanowires was developed for organic vapor detection. The sensing materials were synthesized into nanowires instead of the traditional thin films to increase the surface-to-volume ratio, and then assembled into sensor units. Four different dopants were used to increase the selectivity of the sensor array, including platinum, copper, indium and nickel. Dynamic and static testing methods were utilized to characterize the performance of the sensor array to eight organic vapors. Results indicated high response of the sensor array in the order of tens of ppb. The investigation on response kinetics revealed fast response/recovery time and good repeatability of the sensor array. A database was compiled from the sensor response of four types of nanowire sensors to different vapor concentration levels. Principle component analysis (PCA) was conducted to reduce the dimensionality of the results and to classify the various organic vapors. PCA plots showed that most of the groups were separable, and hence proved the analyte discrimination capability of the sensor array. (C) 2011 Elsevier B.V. All rights reserved.

关键词： sensor array Nanowire Tin oxide Dopant Organic vapor Principle component analysis

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Detecting insect infestation using a polymer based sensor array

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sensorS AND ACTUATORS B-CHEMICAL 2012年 174卷 506-512页

作者： Weerakoon, Kanchana A. Shu, John H. Park, Mi-Kyung Auad, Maria A. Chin, Bryan A. Auburn Univ Dept Mat Engn Auburn AL 36830 USA

An electro-active polymer based sensor array was designed, fabricated and tested to detect volatile organic compounds secreted by plants during insect infestation. The sensor array was inexpensive, and easy to fabricate and could be used for onsite detection of insect infestation. The array consisted of chemical resistor sensors with micro fabricated interdigitated electrodes coated with electro active polymers. Three types of polymers were used as active layers in this study: polythiophene, carbon/polymer and polyaniline. The polymer coatings were deposited onto the sensor platforms via drop casting and spin coating methods. The sensor array was exposed and found to be sensitive to a variety of phytochemical including gamma-terpinene alpha-pinene, p-cymene, farnesene, limonene and cis-hexenyl acetate. The sensor array created a unique fingerprint pattern for each of these chemicals. The fingerprints were further analyzed using principal component analysis. (C) 2012 Elsevier B.V. All rights reserved.

关键词： Insect infestation Polythiophene sensors Carbon polymer composite sensors Polyaniline sensor array

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Metal-Nanoparticle-Supported Nanozyme-Based Colorimetric sensor array for Precise Identification of Proteins and Oral Bacteria

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ACS APPLIED MATERIALS & INTERFACES 2022年第9期14卷 11156-11166页

作者： Lu, Zhanglu Lu, Na Xiao, Yang Zhang, Yunqing Tang, Zisheng Zhang, Min Shanghai Univ Engn Sci Sch Mat Engn Shanghai 201620 Peoples R China Shanghai Jiao Tong Univ Sch Med Shanghai Peoples Hosp 9 Dept Endodont Shanghai 200011 Peoples R China Natl Ctr Stomatol Shanghai 200011 Peoples R China Natl Clin Res Ctr Oral Dis Shanghai 200011 Peoples R China Shanghai Key Lab Stomatol Shanghai 200011 Peoples R China Shanghai Univ Engn Sci Coll Chem & Chem Engn Shanghai 201620 Peoples R China

Convenient, precise, and high-throughput discrimination of multiple bioanalytes is of great significance for an early diagnosis of diseases. array-based pattern recognition has proven to be a powerful tool to detect diverse analytes, but developing sensing elements featuring favorable surface diversity still remains a challenge. In this work, we presented a simple and facile method to prepare programmable metal-nanoparticle (NP)-supported nanozymes (MNNs) as artificial receptors for the accurate identification of multiple proteins and oral bacteria. The in situ reduction of metal NPs on hierarchical MoS2 on polypyrrole (PPy), which generated differential nonspecific interactions with bioanalytes, was envisaged as the encoder to break through the limited supply of the receptor's quantity. As a proof of concept, three metal NPs, i.e., Au, Ag, and Pd NPs, were taken as examples to deposit on PPy@MoS2 as colorimetric probes to construct a cross-reactive sensor array. Based on the principal component analysis (PCA), the proposed MNN sensor array could well discriminate 11 proteins with unique fingerprint-like patterns at a concentration of 250 nM and was sufficiently sensitive to determine individual proteins with a detection limit down to the nanomolar level. Remarkably, two highly similar hemoglobins from different species (hemoglobin and bovine hemoglobin) have been precisely identified. Additionally, five oral bacteria were also well separated from each other without cross-classification at the level of 10(7) CFU mL(-1). Furthermore, the sensor array allowed effective discrimination of complex protein mixtures either at different molar ratios or with minor varying components. Most importantly, the blind samples, proteins in human serums, proteins in simulated body fluid environment, the heat-denatured proteins, and even clinical cancer samples all could be well distinguished by the sensor array, demonstrating the real-world applications in clinical diagnosis.

关键词： metal-nanoparticle-supported nanozyme colorimetric sensor array precise identification proteins oral bacteria

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Quantitative detection of formaldehyde and ammonia gas via metal oxide-modified graphene-based sensor array combining with neural network model

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sensorS AND ACTUATORS B-CHEMICAL 2017年 240卷 55-65页

作者： Zhang, Dongzhi Liu, Jingjing Jiang, Chuanxing Liu, Aiming Xia, Bokai China Univ Petr East China Coll Informat & Control Engn Qingdao 266580 Peoples R China

This paper reports metal oxide (MOx)-decorated graphene-based sensor array combining with back propagation (BP) neural network toward the detection of indoor air pollutant exposure. Tin dioxide (SnO2) nanospheres and copper oxide (CuO) nanoflowers-decorated graphene were used as candidates for formaldehyde and ammonia gas sensing, respectively. The as-synthesized sensing materials were characterized in terms of their nanostructural, morphological and compositional features by SEM, Raman spectra, and XRD. The sensor array was fabricated via one-step hydrothermal route and layer-by-layer (LbL) self-assembly technique on the substrate with interdigital microelectrodes. The sensing properties of M0x/graphene composite toward the mixture gas of ammonia and formaldehyde, such as dynamic response, sensitivity, response/recovery time, and stability, were investigated at room temperature. And furthermore, this work successfully achieved the recognition and quantitative prediction of components in the gas mixture of formaldehyde and ammonia through the combination of MOx/graphene-based sensor array and neural network-based signal processing technologies. (C) 2016 Elsevier B.V. All rights reserved.

关键词： sensor array Graphene Layer-by-layer self-assembly Neural network model

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Micro-miniature autonomous optical sensor array for monitoring ions and metabolites 1: Design, fabrication, and data analysis

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ANALYTICAL SCIENCES 2006年第3期22卷 383-388页

作者： Tohda, K Gratzl, M Case Western Reserve Univ CASE Dept Biomed Engn Cleveland OH 44106 USA

A micro-miniature array of sensing capsules for optical monitoring of pH, potassium and glucose is described. Optode technology translates the respective ionic levels into variable colors of ionophore/dye/polymeric liquid micro-beads stuffed into individual capsules. Glucose is monitored indirectly, by coupling through glucose oxidase (GOX) immobilized in cellulose acetate phthalate (CAP) based microscopic beads that are stuffed into another microcapsule together with pH sensitive optical microscopic beads. The electrolyte and glucose sensing capsules are embedded in a transparent cellulose acetate bar 300 - 500 mu m wide and 2 - 2.5 mm long called the sliver sensor that includes also a white capsule made of micro-beads without dye for optical reference. By adding further capsules custom combinations of analytes can be monitored in biomedical and non-biological contexts. In this work, as an example, design, fabrication and testing of a sliver sensor that could be developed for in vivo use are described.

关键词： .glucose oxidase GOx sensor array Cellulose acetate contexts sliver Glucose sensing stuffed microscopic beads optode Micro-miniature sensing capsules optical reference non-biological

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A QCM sensor array-Based Electronic Tongue With the Optimized Oscillator Circuit Using FPGA

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IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 2018年第2期67卷 431-438页

作者： Aydemir, Firat Ebeoglu, Mehmet Ali Dumlupinar Univ Dept Elect & Elect Engn TR-43100 Kutahya Turkey

In this paper, an electronic tongue (ET) based on a quartz-crystal microbalance (QCM) sensor array was designed and the methods for sensor data analysis were described. In this regard, as chemical sensors, QCM crystals coated with three different phthalocyanines were employed to discriminate toxic chemicals in liquid media. For sensors' preparation, an automatic coating instrument was developed based on the airbrush technique. The oscillator circuits used in the coating instrument and measurement setup were optimized to minimize the noise and mutual interference of the other oscillator circuits in the sensor array. The designed measurement system, which was responsible for collecting and storing data, communicating with a computer, consisted of a field-programmable gate-array-based control unit. The measurement system collected training data from the sensor array, and then computer application using MATLAB used an artificial neural network to find the composition of toxic chemicals in the sample water. The measurement system was tested for three different toxic chemicals, and the average success rate in predicting them was 4.08%. The desired chemicals can be detectable by preparing the necessary sensor array with the proposed ET.

关键词： Electronic tongue (ET) field-programmable gate array (FPGA) liquid sensor quartz-crystal microbalance (QCM) sensor array

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D-A type sensor array for differentiation and identification of white wine varieties based on specific solvent effect activated by CT-LE transition

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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2018年 190卷 318-323页

作者： Han, Jingqi Zhang, Xin Li, Hao Hou, Yue Hou, Jingdan Li, Zhongfeng Yang, Feng Liu, Yang Han, Tianyu Capital Normal Univ Dept Chem Beijing 100048 Peoples R China Dongchangfu Dist Municipal Publ Secur Bur Liaocheng 252000 Shandong Peoples R China Beijing Res Ctr Radiat Applicat Beijing Key Lab Radiat Adv Mat Beijing 100015 Peoples R China

In this work, we synthesize a series of compounds with electron donor (D) and acceptor (A) units. They show general solvent effect in aprotic solvents, suggesting a charge transfer (CT) process. While in protic solvents including water, ethanol and methanol, the spectra exert no polarity-dependence but a remarkable hypochromatic shift together with the fading of CT band. Dynamic analysis implies that intermolecular hydrogen bond will be formed between carboxylic acid and protic solvent, boosting another deactivation pathway that jumps off a bigger energy gap, in other words, favoring the locally excited (LE) state emission. The CT-LE transition involves variations in both absorption and emission spectra, and further poses competition with other mechanisms including activated/restricted intramolecular rotation (IR/RIR). Inspired by the cross-reactivity, we turn our attention to the development of sensor array, in order to identify white wine varieties. The differential spectral responses are recorded, generating multiple factors including absorption wavelength (lambda(ab)), emission wavelength (lambda(em)), absorbance (Abs.) and emission intensity (Int.). These factors are processed with principal component analysis (PCA), creating a three-dimensional fingerprint data base for white wines. The data points in the coordinate system are clustered into 10 different groups, demonstrating a clear differentiation of all the white wines. More importantly, as our final test for whether the sensor array can identify the counterfeits, an adulterated liquor sample, which is provided by police officers, is fingerprinted on the three-dimensional diagram. Its canonical factors fall into an area distinct from the adulterated wine, indicating a clear identification. (C) 2017 Elsevier B.V. All rights reserved.

关键词： sensor array Wine identification Solvent effect Fingerprinting Charge transfer

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