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Balasubramanian V, Niksan O, Jain MC, Golovin K, Zarifi MH. Non-destructive erosive wear monitoring of multi-layer coatings using AI-enabled differential split ring resonator based system. Nat Commun 2023; 14:4916. [PMID: 37582844 PMCID: PMC10427693 DOI: 10.1038/s41467-023-40636-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 08/02/2023] [Indexed: 08/17/2023] Open
Abstract
Unprotected surfaces where a coating has been removed due to erosive wear can catastrophically fail from corrosion, mechanical impingement, or chemical degradation, leading to major safety hazards, financial losses, and even fatalities. As a preventive measure, industries including aviation, marine and renewable energy are actively seeking solutions for the real-time and autonomous monitoring of coating health. This work presents a real-time, non-destructive inspection system for the erosive wear detection of coatings, by leveraging artificial intelligence enabled microwave differential split ring resonator sensors, integrated to a smart, embedded monitoring circuitry. The differential microwave system detects the erosion of coatings through the variations of resonant characteristics of the split ring resonators, located underneath the coating layer while compensating for the external noises. The system's response and performance are validated through erosive wear tests on single- and multi-layer polymeric coatings up to a thickness of 2.5 mm. The system is capable of distinguishing which layer is being eroded (for multi-layer coatings) and estimating the wear depth and rate through its integration with a recurrent neural network-based predictive analytics model. The synergistic combination of artificial intelligence enabled microwave resonators and a smart monitoring system further demonstrates its practicality for real-world coating erosion applications.
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Affiliation(s)
- Vishal Balasubramanian
- Okanagan MicroElectronics and Gigahertz Applications Laboratory, School of Engineering, Faculty of Applied Science, University of British Columbia, Kelowna, BC, V1V 1V7, Canada
| | - Omid Niksan
- Okanagan MicroElectronics and Gigahertz Applications Laboratory, School of Engineering, Faculty of Applied Science, University of British Columbia, Kelowna, BC, V1V 1V7, Canada
| | - Mandeep C Jain
- Okanagan MicroElectronics and Gigahertz Applications Laboratory, School of Engineering, Faculty of Applied Science, University of British Columbia, Kelowna, BC, V1V 1V7, Canada
| | - Kevin Golovin
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, M5S 3G8, Canada
| | - Mohammad H Zarifi
- Okanagan MicroElectronics and Gigahertz Applications Laboratory, School of Engineering, Faculty of Applied Science, University of British Columbia, Kelowna, BC, V1V 1V7, Canada.
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2
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Alaya Y, Souissi R, Toumi M, Madani M, El Mir L, Bouguila N, Alaya S. Annealing effect on the physical properties of TiO 2 thin films deposited by spray pyrolysis. RSC Adv 2023; 13:21852-21860. [PMID: 37475757 PMCID: PMC10354590 DOI: 10.1039/d3ra02387g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 06/27/2023] [Indexed: 07/22/2023] Open
Abstract
Titanium dioxide (TiO2) thin films were deposited on glass substrates at 350 °C using the spray pyrolysis technique. As deposited and annealed thin films were characterized by X-ray diffraction, scanning electron microscopy, UV-VIS spectroscopy, and photodetection. Unlike the as deposited samples which were amorphous, annealed samples show an anatase phase. Films were absorbent in the UV region and the band gap energy decreases from 3.78 eV to 3.4 eV with annealing. The photoresponse of TiO2 photodetectors was recorded under UV (λ1 = 365 nm, λ2 = 254 nm) and visible light illumination by reversible switching (ON/OFF) cycles using DC electrical characterization. Photosensitive properties such as reproducible photosensitivity, responsivity, and detectivity were also studied.
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Affiliation(s)
- Y Alaya
- Gabès University, Laboratoire de Physique des Matériaux et des Nanomatériaux Appliquée à l'Environnement, Faculté des Sciences de Gabès Cité Erriadh, Zrig 6072 Gabès Tunisia
| | - R Souissi
- Carthage University, Laboratoire des Matériaux, Molécules et Applications IPEST BP 51, La Marsa 2070, Tunis Tunisia
| | - M Toumi
- Gabès University, Laboratoire de Physique des Matériaux et des Nanomatériaux Appliquée à l'Environnement, Faculté des Sciences de Gabès Cité Erriadh, Zrig 6072 Gabès Tunisia
| | - M Madani
- Gabès University, Laboratoire de Physique des Matériaux et des Nanomatériaux Appliquée à l'Environnement, Faculté des Sciences de Gabès Cité Erriadh, Zrig 6072 Gabès Tunisia
| | - L El Mir
- Gabès University, Laboratoire de Physique des Matériaux et des Nanomatériaux Appliquée à l'Environnement, Faculté des Sciences de Gabès Cité Erriadh, Zrig 6072 Gabès Tunisia
| | - N Bouguila
- Gabès University, Laboratoire de Physique des Matériaux et des Nanomatériaux Appliquée à l'Environnement, Faculté des Sciences de Gabès Cité Erriadh, Zrig 6072 Gabès Tunisia
| | - S Alaya
- Gabès University, Laboratoire de Physique des Matériaux et des Nanomatériaux Appliquée à l'Environnement, Faculté des Sciences de Gabès Cité Erriadh, Zrig 6072 Gabès Tunisia
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Wiltshire BD, Alijani M, Sopha H, Pavliňák D, Hromadko L, Zazpe R, Thalluri SM, Kolibalova E, Macak JM, Zarifi MH. Gigahertz-Based Visible Light Detection Enabled via CdS-Coated TiO 2 Nanotube Layers. ACS APPLIED MATERIALS & INTERFACES 2023; 15:18379-18390. [PMID: 37010878 DOI: 10.1021/acsami.2c21877] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Detection of visible light is a key component in material characterization techniques and often a key component of quality or purity control analyses for health and safety applications. Here in this work, to enable visible light detection at gigahertz frequencies, a planar microwave resonator is integrated with high aspect ratio TiO2 nanotube (TNT) layer-sensitized CdS coating using the atomic layer deposition (ALD) technique. This unique method of visible light detection with microwave-based sensing improves integration of the light detection devices with digital technology. The designed planar microwave resonator sensor was implemented and tested with resonant frequency between 8.2 and 8.4 GHz and a resonant amplitude between -15 and -25 dB, depending on the wavelength of the illuminated light illumination on the nanotubes. The ALD CdS coating sensitized the nanotubes in visible light up to ∼650 nm wavelengths, as characterized by visible spectroscopy. Furthermore, CdS-coated TNT layer integration with the planar resonator sensor allowed for development of a robust microwave sensing platform with improved sensitivity to green and red light (60 and 1300%, respectively) compared to the blank TNT layers. Moreover, the CdS coating of the TNT layer enhanced the sensor's response to light exposure and resulted in shorter recovery times once the light source was removed. Despite having a CdS coating, the sensor was capable of detecting blue and UV light; however, refining the sensitizing layer could potentially enhance its sensitivity to specific wavelengths of light in certain applications.
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Affiliation(s)
- Benjamin D Wiltshire
- Okanagan MicroElectronics and Gigahertz Applications (OMEGA) Laboratory, School of Engineering, University of British Columbia, Kelowna V1V 1V7, Canada
| | - Mahnaz Alijani
- Okanagan MicroElectronics and Gigahertz Applications (OMEGA) Laboratory, School of Engineering, University of British Columbia, Kelowna V1V 1V7, Canada
- Central European Institute of Technology, Brno University of Technology, Purkynova 123, Brno 61200, Czech Republic
| | - Hanna Sopha
- Central European Institute of Technology, Brno University of Technology, Purkynova 123, Brno 61200, Czech Republic
- Center of Materials and Nanotechnology, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, 53002 Pardubice, Czech Republic
| | - David Pavliňák
- Central European Institute of Technology, Brno University of Technology, Purkynova 123, Brno 61200, Czech Republic
| | - Ludek Hromadko
- Central European Institute of Technology, Brno University of Technology, Purkynova 123, Brno 61200, Czech Republic
- Center of Materials and Nanotechnology, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, 53002 Pardubice, Czech Republic
| | - Raul Zazpe
- Central European Institute of Technology, Brno University of Technology, Purkynova 123, Brno 61200, Czech Republic
- Center of Materials and Nanotechnology, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, 53002 Pardubice, Czech Republic
| | - Sitaramanjaneya M Thalluri
- Central European Institute of Technology, Brno University of Technology, Purkynova 123, Brno 61200, Czech Republic
- Center of Materials and Nanotechnology, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, 53002 Pardubice, Czech Republic
| | - Eva Kolibalova
- Central European Institute of Technology, Brno University of Technology, Purkynova 123, Brno 61200, Czech Republic
| | - Jan M Macak
- Central European Institute of Technology, Brno University of Technology, Purkynova 123, Brno 61200, Czech Republic
- Center of Materials and Nanotechnology, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, 53002 Pardubice, Czech Republic
| | - Mohammad H Zarifi
- Okanagan MicroElectronics and Gigahertz Applications (OMEGA) Laboratory, School of Engineering, University of British Columbia, Kelowna V1V 1V7, Canada
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4
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Microwave-sensor-node integrated into a short-range wireless sensor network. Sci Rep 2023; 13:2075. [PMID: 36747061 PMCID: PMC9902451 DOI: 10.1038/s41598-023-28964-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 01/27/2023] [Indexed: 02/08/2023] Open
Abstract
This paper presents the first microwave-sensor-node integrated into a short-range wireless sensor network based on ZigBee technology. The node includes an analog front-end circuit, a Frequency Modulated Continuous Wave generator, an Analog-to-Digital-Converter module, a transceiver, a power unit, a processing unit and a new one-port dielectric permittivity sensor which is able to measuring the separation of structural cracks by the reflection coefficient measured in microwave frequencies. The analog front-end is composed of a pair of power dividers, an isolator and a mixer. The dielectric permittivity sensor is based on a patch antenna of variable length. The processing unit and transceiver are implemented with an Arduino UNO and an XBee module respectively. Additionally, the methodology for data processing is presented and the results of the measurement of a synthetic crack are presented. The results show that the system was successfully implemented with a sensitivity of 0.07 GHz/mm, for an opening range of between 0 and 5 mm and for a frequency range ranging from 2.782 GHz to 3.131 GHz. It is important to mention that the measurement was done remotely, placing the sensor 3 m from the client PC.
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Xu J, Liang C, Gao Z, Song YY. Construction of nanoreactors on TiO2 nanotube arrays as a POCT device for sensitive colorimetric detection. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2022.107863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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6
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Wiltshire BD, Alijani M, Mohammadi S, Hosseini A, Macak JM, Zarifi MH. High-Frequency TiO 2 Nanotube-Adapted Microwave Coplanar Waveguide Resonator for High-Sensitivity Ultraviolet Detection. ACS APPLIED MATERIALS & INTERFACES 2022; 14:6203-6211. [PMID: 35073695 DOI: 10.1021/acsami.1c21741] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Ultraviolet (UV) sensors are a key component in growing applications such as water quality treatment and environmental monitoring, with considerable interest in their miniaturization and enhanced operation. This work presents a passive gold coplanar waveguide split ring resonator integrated with anodic self-organized TiO2 nanotube (TNT) membranes with a thickness of 20 μm to provide real-time UV detection. The resonator operated as a one-port device to capture the reflection coefficient (S11) signal, with a center frequency of 16 GHz and a notch amplitude of -88 dB. It was experimentally analyzed for its UV sensing capability in the range of 36.5-463 μW/cm2. The high-frequency resonator was improved through design choices including the addition of a tapered input transmission line, wire bonding for practical device design, and an interdigitated capacitive ring gap. The high frequency also helped mitigate noise due to water vapor or environmental contaminants. S11 amplitude variation was found through both experiments and modeling to follow a linear trend with UV illumination intensity. The resonator exhibited over 45 ± 2 dB shift in the resonant amplitude under the highest UV illumination conditions, with a sensitivity of 0.084 dB/μW cm-2 and the potential to sense UV intensity as low as 2.7 μW/cm2. The presented device enabled a repeatable and accurate microwave response under UV illumination with very high sensitivity, entirely through the use of passive circuit elements.
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Affiliation(s)
- Benjamin D Wiltshire
- Okanagan MicroElectronics and Gigahertz Applications (OMEGA) Laboratory, School of Engineering, University of British Columbia, Vancouver V1V 1V7, Canada
| | - Mahnaz Alijani
- Okanagan MicroElectronics and Gigahertz Applications (OMEGA) Laboratory, School of Engineering, University of British Columbia, Vancouver V1V 1V7, Canada
- Central European Institute of Technology, Brno University of Technology, Purkynova 123, Brno 61200, Czech Republic
| | - Sevda Mohammadi
- Okanagan MicroElectronics and Gigahertz Applications (OMEGA) Laboratory, School of Engineering, University of British Columbia, Vancouver V1V 1V7, Canada
| | - Arezoo Hosseini
- Okanagan MicroElectronics and Gigahertz Applications (OMEGA) Laboratory, School of Engineering, University of British Columbia, Vancouver V1V 1V7, Canada
| | - Jan M Macak
- Central European Institute of Technology, Brno University of Technology, Purkynova 123, Brno 61200, Czech Republic
- Center of Materials and Nanotechnology, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, Pardubice 53002, Czech Republic
| | - Mohammad H Zarifi
- Okanagan MicroElectronics and Gigahertz Applications (OMEGA) Laboratory, School of Engineering, University of British Columbia, Vancouver V1V 1V7, Canada
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Kazemi KK, Zarifi T, Mohseni M, Narang R, Golovin K, Zarifi MH. Smart Superhydrophobic Textiles Utilizing a Long-Range Antenna Sensor for Hazardous Aqueous Droplet Detection plus Prevention. ACS APPLIED MATERIALS & INTERFACES 2021; 13:34877-34888. [PMID: 34254781 DOI: 10.1021/acsami.1c07880] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
This paper demonstrates the feasibility of a long-range antenna sensor embedded underneath a liquid repellent fabric to be employed as a wearable sensor in personal protective fabrics. The sensor detects and monitors hazardous aqueous liquids on the outer layer of fabrics, to add an additional layer of safety for professionals working in hazardous environments. A modified patch antenna was designed to include a meandering-shaped resonant structure, which was embedded underneath the fabric. Superhydrophobic fabrics were prepared using silica nanoparticles and a low-surface-energy fluorosilane. 4 to 20 μL droplets representing hazardous aqueous solutions were drop-cast on the fabrics to investigate the performance of the embedded antenna sensor. Long-range (S21) measurements at a distance of 2-3 m were performed using the antenna sensor with treated and untreated fabrics. The antenna sensor successfully detected the liquid for both types of fabrics. The resonant frequency sensitivity of the antenna sensor underneath the treated fabric exhibiting superhydrophobicity was measured as 370 kHz/μL, and 1 MHz/μL for the untreated fabric. The results demonstrate that the antenna sensor is a good candidate for wearable hazardous aqueous droplet detection on fabrics.
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Affiliation(s)
- Kasra Khorsand Kazemi
- Okanagan MicroElectronics and Gigahertz Applications Laboratory, School of Engineering, University of British Columbia, Kelowna V1V 1V7, British Columbia, Canada
| | - Telnaz Zarifi
- Okanagan Polymer Engineering Research & Applications Laboratory, School of Engineering, University of British Columbia, Kelowna V1V 1V7, British Columbia, Canada
| | - Majid Mohseni
- Okanagan Polymer Engineering Research & Applications Laboratory, School of Engineering, University of British Columbia, Kelowna V1V 1V7, British Columbia, Canada
| | - Rakesh Narang
- Okanagan MicroElectronics and Gigahertz Applications Laboratory, School of Engineering, University of British Columbia, Kelowna V1V 1V7, British Columbia, Canada
| | - Kevin Golovin
- Okanagan Polymer Engineering Research & Applications Laboratory, School of Engineering, University of British Columbia, Kelowna V1V 1V7, British Columbia, Canada
| | - Mohammad H Zarifi
- Okanagan MicroElectronics and Gigahertz Applications Laboratory, School of Engineering, University of British Columbia, Kelowna V1V 1V7, British Columbia, Canada
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A High-Resolution Reflective Microwave Planar Sensor for Sensing of Vanadium Electrolyte. SENSORS 2021; 21:s21113759. [PMID: 34071551 PMCID: PMC8199298 DOI: 10.3390/s21113759] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/12/2021] [Accepted: 05/22/2021] [Indexed: 12/31/2022]
Abstract
Microwave planar sensors employ conventional passive complementary split ring resonators (CSRR) as their sensitive region. In this work, a novel planar reflective sensor is introduced that deploys CSRRs as the front-end sensing element at fres=6 GHz with an extra loss-compensating negative resistance that restores the dissipated power in the sensor that is used in dielectric material characterization. It is shown that the S11 notch of -15 dB can be improved down to -40 dB without loss of sensitivity. An application of this design is shown in discriminating different states of vanadium redox solutions with highly lossy conditions of fully charged V5+ and fully discharged V4+ electrolytes.
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Mohammadi S, Nadaraja AV, Luckasavitch K, Jain MC, June Roberts D, Zarifi MH. A Label-Free, Non-Intrusive, and Rapid Monitoring of Bacterial Growth on Solid Medium Using Microwave Biosensor. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2020; 14:2-11. [PMID: 31715571 DOI: 10.1109/tbcas.2019.2952841] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Microwave resonator sensors are attractive for their contactless and label-free capability of monitoring bacterial growth in liquid media. This paper outlines a new label-free microwave biosensor based on a pair of planar split ring resonators for non-invasive monitoring of bacterial growth on a solid agar media. The sensor is comprised of two split ring resonators with slightly different resonant frequencies for differential operation. The transmission coefficient (S21) of the sensor is considered as the sensor's response with a designed and measured quality factor above 200 to ensure a high-resolution operation of the biosensor. Two resonant frequencies of 1.95 and 2.11 GHz represent the sensing signal and the reference signal, respectively. The developed sensor demonstrates high performance in monitoring the growth dynamics of Escherichia coli (E. coli) on Luria-Bertani (LB) agar with 4 mm thickness. The sensor's resonant amplitude response demonstrated 0.5 dB variation corresponding to the bacterial growth over 48 hours when bacteria were spread on LB agar starting with initial OD600 = 1.5. Moreover, 0.6 dB change in the sensor's response was observed over 96 hours of bacterial growth starting with an initial OD600 = 1.17 spotted on LB agar. The measured results fit well to the curves created using Richards' bacterial growth model, showing the strength of the sensor as a potential candidate for use in predictive food microbiology systems.
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Xue Q, Tang X, Li Y, Liu H, Duan X. Contactless and Simultaneous Measurement of Water and Acid Contaminations in Oil Using a Flexible Microstrip Sensor. ACS Sens 2020; 5:171-179. [PMID: 31885255 DOI: 10.1021/acssensors.9b01965] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The assessment of the petroleum product quality often involves multiple indicators, among which water content and acid value are two major parameters. The complexity of an oil sample and the narrow space in pipeline transport make it difficult to monitor the oil quality in real-time. Considering the practical requirements, a new type of flexible microstrip sensor is proposed in this work. The shape and line width of the microstrip sensor are studied and optimized by theory and experiments. The proposed square spiral-based microstrip sensor has good water content detection resolution at high frequencies with less acid interference, and it can determine the acid value in the low-frequency band. The sensor surface is further passivated, protecting it from direct contact with the oil sample to enhance the electrochemical robustness, and still achieves good detection linearity and high sensitivity. After encapsulation on a flexible substrate, the proposed microstrip sensor realized the non-contact determination of the water content and acid value of oil at the same time, which is only a few millimeters in size and can conform to various tubing wall shapes. Due to the fact that the manufacture of the sensor is CMOS-compatible, we expect it to be readily applied to many other miniaturized chemical-sensing applications.
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Affiliation(s)
- Qiannan Xue
- State Key Laboratory of Precision Measuring Technology & Instruments, School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China
| | - Xiecheng Tang
- State Key Laboratory of Precision Measuring Technology & Instruments, School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China
- Sino-european Institute of Aviation Engineering, College of Electronic Information and Automation, Civil Aviation University of China, Tianjin 300300, China
| | - Yanna Li
- State Key Laboratory of Precision Measuring Technology & Instruments, School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China
| | - Haitao Liu
- Sino-european Institute of Aviation Engineering, College of Electronic Information and Automation, Civil Aviation University of China, Tianjin 300300, China
| | - Xuexin Duan
- State Key Laboratory of Precision Measuring Technology & Instruments, School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China
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Zhang Y, Xu W, Xu X, Yang W, Li S, Chen J, Fang X. Low-cost writing method for self-powered paper-based UV photodetectors utilizing Te/TiO 2 and Te/ZnO heterojunctions. NANOSCALE HORIZONS 2019; 4:452-456. [PMID: 32254097 DOI: 10.1039/c8nh00401c] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
It has always been a challenge to prepare self-powered ultraviolet photodetectors (UV PDs) utilizing a green, facile and low-cost method. Here, we provide such an approach for fabricating self-powered photodetectors based on Te nanowire/TiO2 nanoparticle (NP) and Te nanowire/ZnO nanoparticle (NP) heterojunctions. It is noteworthy that such devices were prepared via simply brushing non-toxic solution-processed Te nanowires and commercial TiO2 and ZnO nanoparticles onto paper. The as-obtained UV PDs can work under zero bias due to photovoltaic effects from the Te/TiO2 and Te/ZnO heterojunctions. This study not only presents high-performance UV PDs, but also provides a general and effective method for developing environmentally-friendly and energy-efficient optoelectronic devices for practical applications. The concept of employing daily-use brushes and recyclable paper provides a facile way to fabricate green low-cost PDs.
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Affiliation(s)
- Yong Zhang
- Department of Materials Science, Fudan University, Shanghai 200433, China.
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Frau I, Wylie S, Cullen J, Korostynska O, Byrne P, Mason A. Microwaves and Functional Materials: A Novel Method to Continuously Detect Metal Ions in Water. MODERN SENSING TECHNOLOGIES 2019. [DOI: 10.1007/978-3-319-99540-3_9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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13
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Zarifi MH, Wiltshire BD, Mahdi N, Shankar K, Daneshmand M. Distinguishing between Deep Trapping Transients of Electrons and Holes in TiO 2 Nanotube Arrays Using Planar Microwave Resonator Sensor. ACS APPLIED MATERIALS & INTERFACES 2018; 10:29857-29865. [PMID: 29767958 DOI: 10.1021/acsami.8b03629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A large signal direct current (DC) bias and a small signal microwave bias were simultaneously applied to TiO2 nanotube membranes mounted on a planar microwave resonator. The DC bias modulated the electron concentration in the TiO2 nanotubes and was varied between 0 and 120 V in this study. Transients immediately following the application and removal of DC bias were measured by monitoring the S-parameters of the resonator as a function of time. The DC bias stimulated Poole-Frenkel-type trap-mediated electrical injection of excess carriers into TiO2 nanotubes, which resulted in a near-constant resonant frequency but a pronounced decrease in the microwave amplitude due to free electron absorption. When ultraviolet illumination and DC bias were both present and then stepwise removed, the resonant frequency shifted due to trapping-mediated change in the dielectric constant of the nanotube membranes. Characteristic lifetimes of 60-80, 300-800, and ∼3000 s were present regardless of whether light or bias was applied and were also observed in the presence of a hole scavenger, which we attributed to oxygen adsorption and deep electron traps, whereas another characteristic lifetime >8000 s was only present when illumination was applied, and is attributed to the presence of hole traps.
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Affiliation(s)
- Mohammad H Zarifi
- School of Engineering , University of British Columbia , Kelowna , British Columbia V1V 1V7 , Canada
| | - Benjamin D Wiltshire
- Department of Electrical and Computer Engineering , University of Alberta , Edmonton , Alberta T6G 2V4 , Canada
| | - Najia Mahdi
- Department of Electrical and Computer Engineering , University of Alberta , Edmonton , Alberta T6G 2V4 , Canada
| | - Karthik Shankar
- Department of Electrical and Computer Engineering , University of Alberta , Edmonton , Alberta T6G 2V4 , Canada
| | - Mojgan Daneshmand
- Department of Electrical and Computer Engineering , University of Alberta , Edmonton , Alberta T6G 2V4 , Canada
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