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13 pages, 3791 KiB

Open AccessArticle

In Situ Growth of Dopamine on QCM for Humidity Detection

by Pengjia Qi, Ziwei Xu and Tong Zhang

Chemosensors 2022, 10(12), 522; https://doi.org/10.3390/chemosensors10120522 - 8 Dec 2022

Cited by 2 | Viewed by 1273

Abstract

Polydopamine (PDA) films were successfully prepared on quartz crystal microbalance (QCM) by in-situ growth method, and the obtained QCM sensor was used for humidity detection. Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were used to study the chemical composition and [...] Read more.

Polydopamine (PDA) films were successfully prepared on quartz crystal microbalance (QCM) by in-situ growth method, and the obtained QCM sensor was used for humidity detection. Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were used to study the chemical composition and microstructure of the in-situ grown PDA sensitive films. The experimental results showed that the PDA-QCM humidity sensor with 2 h polymerization growth times (2-PDA-QCM) owned high sensitivity (20.77 Hz/% RH), good selectivity, short response/recovery time (5 s/11 s) and acceptable long-term stability. In addition, the energy loss of the sensors fabricated under different conditions was investigated by impedance analysis. Based on all the test results, it is concluded that the combination of in-situ growth method and QCM can produce a room temperature humidity sensor with excellent performance. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Flexible and Wearable Chemo- and Bio- Sensors)

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10 pages, 2279 KiB

Open AccessArticle

Au/La Co-Modified In₂O₃ Nanospheres for Highly Sensitive Ethanol Gas Detection

by Hang Liu, Peihua Li, Bing Liu, Tong Zhang and Yuhong Zhang

Chemosensors 2022, 10(10), 392; https://doi.org/10.3390/chemosensors10100392 - 24 Sep 2022

Cited by 4 | Viewed by 1300

Abstract

In this paper, the gas-sensitive properties of co-doping the rare earth element La and noble metal Au in In₂O₃ nanospheres were investigated for ethanol detection. Through XRD and SEM characterization, the grain size of La-In₂O₃ and Au/La-In [...] Read more.

In this paper, the gas-sensitive properties of co-doping the rare earth element La and noble metal Au in In₂O₃ nanospheres were investigated for ethanol detection. Through XRD and SEM characterization, the grain size of La-In₂O₃ and Au/La-In₂O₃ nanoparticles was smaller than that of pure In₂O₃. As expected, the smaller grain size sample has shown a higher response for ethanol vapor. Compared with the pure In₂O₃ nanoparticles, the 2 mol%Au/2 mol%La-In₂O₃ sample has shown better ethanol-sensing properties, including higher sensitivity (S = 381) and lower operating temperature (210 °C) for 100 ppm ethanol vapor. In addition, the Au/La-In₂O₃ sensor presented a fast response time (1 s). The enhancement mechanism of the ethanol response was discussed for Au/La-In₂O₃ nanoparticles. The obtained experimental results would provide a new road for designing higher response sensors. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Flexible and Wearable Chemo- and Bio- Sensors)

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11 pages, 3236 KiB

Open AccessArticle

Influence of Positive Ion (Al³⁺, Sn⁴⁺, and Sb⁵⁺) Doping on the Basic Resistance and Sensing Performances of ZnO Nanoparticles Based Gas Sensors

by Peng Zhang, Shuang Cao, Ning Sui, Yifeng Xu, Tingting Zhou, Yuan He and Tong Zhang

Chemosensors 2022, 10(9), 364; https://doi.org/10.3390/chemosensors10090364 - 10 Sep 2022

Viewed by 1887

Abstract

Despite potential advantages of metal oxide semiconductors (MOSs)-based gas sensors, the limitation of very high baseline resistance is still unsatisfactory for practical application. By means of element doping, the performance of metal oxide materials used as gas sensors can be optimized. Herein, different [...] Read more.

Despite potential advantages of metal oxide semiconductors (MOSs)-based gas sensors, the limitation of very high baseline resistance is still unsatisfactory for practical application. By means of element doping, the performance of metal oxide materials used as gas sensors can be optimized. Herein, different cations (Al³⁺, Sn⁴⁺, and Sb⁵⁺) doped ZnO nanoparticles were synthesized and used as the acetone sensing materials. Results show that the resistance of sensors based on Sn⁴⁺ doped ZnO was significantly reduced (from 5.18 to 0.28 MΩ) at 270 °C without sacrificing the acetone sensing responses. In addition, the gas sensor also exhibited the fast response/recovery time (1/10 s) and great long-term stability. The electron compensation and improved adsorbing oxygen ability for the Sn⁴⁺ doped ZnO nanoparticles contributed to the relatively low resistance and enhanced acetone sensing performances. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Flexible and Wearable Chemo- and Bio- Sensors)

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11 pages, 5481 KiB

Open AccessArticle

Ba-Modified ZnO Nanorods Loaded with Palladium for Highly Sensitive and Rapid Detection of Methane at Low Temperatures

by Yijing Cai, Shirui Luo, Renjie Chen, Junxia Yu and Lan Xiang

Chemosensors 2022, 10(9), 346; https://doi.org/10.3390/chemosensors10090346 - 23 Aug 2022

Cited by 5 | Viewed by 1625

Abstract

Exploring novel sensing materials to rapidly identify CH₄ at low temperatures is crucial for various practical applications. Herein, a novel ZnO-xBa/Pd with Ba of cocatalyst loading from 0 to 2.0 wt% was facilely prepared using a two-step impregnation method to improve the [...] Read more.

Exploring novel sensing materials to rapidly identify CH₄ at low temperatures is crucial for various practical applications. Herein, a novel ZnO-xBa/Pd with Ba of cocatalyst loading from 0 to 2.0 wt% was facilely prepared using a two-step impregnation method to improve the sensitivity of the CH₄ gas sensor. The microstructure, chemical states of the elements, and surface properties of ZnO-Ba/Pd were characterized, and the gas-sensitive performance of ZnO-Ba/Pd sensors was investigated. Compared to methane sensors based on other inorganic and organic material sensors, the sensor based on ZnO-1.0Ba/Pd exhibited a faster response/recovery time (1.4 s/8.3 s) and higher response (368.2%) for 5000 ppm CH₄ at a lower temperature (170 °C). Moreover, the ZnO-1.0Ba/Pd sensor exhibited full reversibility and long-term stability, as well as excellent selectivity at 170 °C. The excellent performance of the ZnO-Ba/Pd sensor was attributed to the electron donation by Ba, which increases the electron density around Pd, thus enhancing the catalytic activity of Pd and promoting oxygen adsorption on the ZnO surface. The present work provides a method for the rational design and synthesis of sensitive materials in practical CH₄ detection. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Flexible and Wearable Chemo- and Bio- Sensors)

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11 pages, 2806 KiB

Open AccessArticle

Highly Dispersive Palladium Loading on ZnO by Galvanic Replacements with Improved Methane Sensing Performance

by Renjie Chen, Shirui Luo, Dan Xie, Yangxin Yu and Lan Xiang

Chemosensors 2022, 10(8), 329; https://doi.org/10.3390/chemosensors10080329 - 12 Aug 2022

Cited by 13 | Viewed by 1730

Abstract

Methane detection is important for the safety of production and life. Metal oxide semiconductor (MOS) methane detection is a mature and widely used technology but still experiences problems such as unsatisfying low-temperature sensing performances. In this study, ZnO/Pd with Pd nanoparticles of different [...] Read more.

Methane detection is important for the safety of production and life. Metal oxide semiconductor (MOS) methane detection is a mature and widely used technology but still experiences problems such as unsatisfying low-temperature sensing performances. In this study, ZnO/Pd with Pd nanoparticles of different diameters was prepared to study the influence of Pd dispersion on CH₄ sensing properties. Results showed that CH₄ sensing enhancements were positively correlated with the dispersity of Pd. Moreover, by galvanic replacement using Ag as the sacrificial template, a highly dispersive loading of Pd on ZnO was realized, and the CH₄ sensing performance was further enhanced while the amount of Pd reduced from 1.35 wt% to 0.26 wt%. Experiments and DFT calculation indicated that improved CH₄ sensing performance resulted from abundant catalytic sites induced by highly dispersed Pd NPs and the enhanced CH₄ adsorption on positively charged Pds caused by electrons transferred from Pd to Ag. This study provides a strategy to achieve high dispersion of Pd to maximize the utilization of noble metal, which is promising for lowering the cost of the MOS-based CH₄ sensors. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Flexible and Wearable Chemo- and Bio- Sensors)

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14 pages, 4048 KiB

Open AccessArticle

Gas Sensitive Characteristics of Polyaniline Decorated with Molybdenum Ditelluride Nanosheets

by Xinpeng Chen, Xiangdong Chen, Xing Ding and Xiang Yu

Chemosensors 2022, 10(7), 264; https://doi.org/10.3390/chemosensors10070264 - 6 Jul 2022

Cited by 4 | Viewed by 1603

Abstract

In this work, hydrochloric acid (HCl)-doped molybdenum ditelluride (MoTe₂) nanosheets/polyaniline (PANI) nanofiber composites are prepared by in situ chemical oxidation polymerization, and then the composites are deposited on interdigital electrodes (IDEs) to fabricate a NH₃ gas sensor. Morphological analysis of [...] Read more.

In this work, hydrochloric acid (HCl)-doped molybdenum ditelluride (MoTe₂) nanosheets/polyaniline (PANI) nanofiber composites are prepared by in situ chemical oxidation polymerization, and then the composites are deposited on interdigital electrodes (IDEs) to fabricate a NH₃ gas sensor. Morphological analysis of the composites reveals that the PANI fibers are deposited on 2D MoTe₂ sheets, showing a porous mesh microstructure structure with a more continuous distribution of PANI layer. FTIR spectrum analysis indicates the interaction between the MoTe₂ nanosheets and the PANI in the MoTe₂/PANI composites. The results demonstrate that the as-prepared MoTe₂/PANI composites exhibit higher response than the pure PANI, in particular, the 8 wt.% MoTe₂/PANI composites display about 4.23 times enhancement in response value toward 1000 ppm NH₃ gas compared with the pure PANI. The enhanced NH₃ gas-sensitive properties may be due to the increasing surface area of MoTe₂/PANI composite films and the possible interaction of the P-N heterojunctions formed between PANI and the 2H-MoTe₂ nanosheets. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Flexible and Wearable Chemo- and Bio- Sensors)

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10 pages, 2525 KiB

Open AccessArticle

The Effect of Thin Film Fabrication Techniques on the Performance of rGO Based NO₂ Gas Sensors at Room Temperature

by Shazrah Shahzad, Huaipeng Wang, Weiwei Li, Yilin Sun, Dan Xie and Tianling Ren

Chemosensors 2022, 10(3), 119; https://doi.org/10.3390/chemosensors10030119 - 21 Mar 2022

Cited by 6 | Viewed by 3141

Abstract

Reduced graphene oxide (rGO) has attracted enormous interest as a promising candidate material for gas detection due to its large specific surface areas. In our work, rGO films were fabricated on a large scale using dip-coating and spin-coating methods for the detection of [...] Read more.

Reduced graphene oxide (rGO) has attracted enormous interest as a promising candidate material for gas detection due to its large specific surface areas. In our work, rGO films were fabricated on a large scale using dip-coating and spin-coating methods for the detection of nitrogen dioxide (NO₂) gas at room temperature. The influence of different test environments on the sensing performance, including the test atmosphere, gas flow and gas pressure was evaluated. The response time of the dip-coating method was 573 s with a long recovery period of 639 s and for the spin-coating method, the response time and recovery time was 386 s and 577 s, respectively. In addition, the spin-coated sensor exhibited high selectivity to NO₂, with the response increasing by more than 20% (for 15 ppm NO₂) as compared with that for HCHO, NH₃, and CH₄. Our results indicated that the spin coating method was more suitable for rGO-based gas sensors with higher performance. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Flexible and Wearable Chemo- and Bio- Sensors)

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12 pages, 2563 KiB

Open AccessArticle

Electrochemical Biosensor Employing Bi₂S₃ Nanocrystals-Modified Electrode for Bladder Cancer Biomarker Detection

by Yunong Zhao, Yanbing Tao, Qing Huang, Jing Huang, Jiayu Kuang, Ruiqin Gu, Pei Zeng, Hua-Yao Li, Huageng Liang and Huan Liu

Chemosensors 2022, 10(2), 48; https://doi.org/10.3390/chemosensors10020048 - 27 Jan 2022

Cited by 9 | Viewed by 4549

Abstract

Bladder cancer is a kind of malignant tumor with high incidence in the urinary system, complex pathogenic causes, and the high recurrence rate. Biosensors capable of rapid, on site, and accurate bladder cancer diagnosis method continue to be lacking. Here, the electrochemical biosensor [...] Read more.

Bladder cancer is a kind of malignant tumor with high incidence in the urinary system, complex pathogenic causes, and the high recurrence rate. Biosensors capable of rapid, on site, and accurate bladder cancer diagnosis method continue to be lacking. Here, the electrochemical biosensor for detecting cytokeratin 18 (CK18, bladder cancer biomarker) was constructed based on the chemically modified electrode (CME). The work electrode (WE) was modified by bismuth sulfide semiconductor nanocrystals (Bi₂S₃ NCs), and then immobilized with CK18 antibodies and blocking agents to complete the electrode preparation. The results indicated that the interface of a flexible carbon electrode with Bi₂S₃ NCs film was steady with reliable charge transfer capability. With the large specific area and quantum size effect, the proposed sensor could detect CK18 antigen protein with an ultralow detection limit of 1.87 fM (fmol L⁻¹) and wide linear dynamic range of 1–1000 pg mL⁻¹, respectively. Detecting results could be read in less than 30 s with the portable, planar flexible CME. The sensitive and specific electrochemical biosensor possessed the characteristics of rapidity, ease-of-use, and non-invasive detection, indicating the application prospect in the early screening of bladder cancer and other diseases. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Flexible and Wearable Chemo- and Bio- Sensors)

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11 pages, 1028 KiB

Open AccessArticle

Surface Acoustic Wave Biosensor with Laser-Deposited Gold Layer Having Controlled Porosity

by Dana Miu, Izabela Constantinoiu, Valentina Dinca and Cristian Viespe

Chemosensors 2021, 9(7), 173; https://doi.org/10.3390/chemosensors9070173 - 8 Jul 2021

Cited by 2 | Viewed by 2074

Abstract

Laser-deposited gold immobilization layers having different porosities were incorporated into love wave surface acoustic wave sensors (LW-SAWs). Variation of pulsed laser deposition parameters allows good control of the gold film morphology. Biosensors with various gold film porosities were tested using the biotin–avidin reaction. [...] Read more.

Laser-deposited gold immobilization layers having different porosities were incorporated into love wave surface acoustic wave sensors (LW-SAWs). Variation of pulsed laser deposition parameters allows good control of the gold film morphology. Biosensors with various gold film porosities were tested using the biotin–avidin reaction. Control of the Au layer morphology is important since the biotin and avidin layer morphologies closely follow that of the gold. The response of the sensors to biotin/avidin, which is a good indicator of biosensor performance, is improved when the gold layer has increased porosity. Given the sizes of the proteins, the laser-deposited porous gold interfaces have optimal pore dimensions to ensure protein stability. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Flexible and Wearable Chemo- and Bio- Sensors)

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Review

Jump to: Research

18 pages, 2423 KiB

Open AccessReview

Conductive Hydrogel-Based Electrochemical Sensor: A Soft Platform for Capturing Analyte

by Li Fu, Aimin Yu and Guosong Lai

Chemosensors 2021, 9(10), 282; https://doi.org/10.3390/chemosensors9100282 - 4 Oct 2021

Cited by 36 | Viewed by 5709

Abstract

Electrode modifications for electrochemical sensors attract a lot of attention every year. Among them, hydrogels are a relatively special class of electrode modifier. Since hydrogels often contain polymers, even though they are conductive polymers, they are not ideal electrode modifiers because of their [...] Read more.

Electrode modifications for electrochemical sensors attract a lot of attention every year. Among them, hydrogels are a relatively special class of electrode modifier. Since hydrogels often contain polymers, even though they are conductive polymers, they are not ideal electrode modifiers because of their poor conductivity. However, the micro-aqueous environment and the three-dimensional structure of hydrogels are an excellent platform for immobilizing bioactive molecules and maintaining their activity. This gives the hydrogel-modified electrochemical sensor the potential to perform specific recognition. At the same time, the rapid development of nanomaterials also makes the composite hydrogel have good electrical conductivity. This has led many scientists to become interested in hydrogel-based electrochemical sensors. In this review, we summarize the development process of hydrogel-based electrochemical sensors, starting from 2000. Hydrogel-based electrochemical sensors were initially used only as a carrier for biomolecules, mostly for loading enzymes and for specific recognition. With the widespread use of noble metal nanoparticles and carbon materials, hydrogels can now be used to prepare enzyme-free sensors. Although there are some sporadic studies on the use of hydrogels for practical applications, the vast majority of reports are still limited to the detection of common model molecules, such as glucose and H₂O₂. In the review, we classify hydrogels according to their different conducting strategies, and present the current status of the application of different hydrogels in electrochemical sensors. We also summarize the advantages and shortcomings of hydrogel-based electrochemical sensors. In addition, future prospects regarding hydrogel for electrochemical sensor use have been provided at the end. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Flexible and Wearable Chemo- and Bio- Sensors)

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