28 results on '"Chrimes AF"'
Search Results
2. Ionic imbalance induced self-propulsion of liquid metals
- Author
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Zavabeti, A, Daeneke, T, Chrimes, AF, O'Mullane, AP, Zhen Ou, J, Mitchell, A, Khoshmanesh, K, Kalantar-Zadeh, K, Zavabeti, A, Daeneke, T, Chrimes, AF, O'Mullane, AP, Zhen Ou, J, Mitchell, A, Khoshmanesh, K, and Kalantar-Zadeh, K
- Abstract
Components with self-propelling abilities are important building blocks of small autonomous systems and the characteristics of liquid metals are capable of fulfilling self-propulsion criteria. To date, there has been no exploration regarding the effect of electrolyte ionic content surrounding a liquid metal for symmetry breaking that generates motion. Here we show the controlled actuation of liquid metal droplets using only the ionic properties of the aqueous electrolyte. We demonstrate that pH or ionic concentration gradients across a liquid metal droplet induce both deformation and surface Marangoni flow. We show that the Lippmann dominated deformation results in maximum velocity for the self-propulsion of liquid metal droplets and illustrate several key applications, which take advantage of such electrolyte-induced motion. With this finding, it is possible to conceive the propulsion of small entities that are constructed and controlled entirely with fluids, progressing towards more advanced soft systems.
- Published
- 2016
3. Dielectrophoretically controlled Fresnel zone plate.
- Author
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Chrimes, AF, Khodasevych, I, Mitchell, A, Rosengarten, G, Kalantar-zadeh, K, Chrimes, AF, Khodasevych, I, Mitchell, A, Rosengarten, G, and Kalantar-zadeh, K
- Abstract
Switchability is a highly sought after feature for planar optical systems. Suspensions of nanomaterials can be used for generating controllable changes in such systems. We report a planar diffractive microfluidic lens which integrates controlled dielectrophoresis (DEP) for trapping suspended nanomaterials. Silicon and tungsten oxide nanoparticle suspensions are used. These nanomaterials are trapped in such a way as to form alternating opaque and transparent rings using the DEP forces on demand. These rings form a planar diffractive Fresnel zone plate to focus the incident light. The Fresnel zone plate is tuned for the visible light region and the lens can be turned on (DEP applied) or off (DEP removed) in a controlled manner. This proof of concept demonstration can be further expanded for a variety of switchable optical devices and can be integrated with lab-on-a-chip and optofluidic devices.
- Published
- 2015
4. Detection of changes in regional colonic fermentation in response to supplementing a low FODMAP diet with dietary fibres by hydrogen concentrations, but not by luminal pH.
- Author
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So D, Yao CK, Gill PA, Thwaites PA, Ardalan ZS, McSweeney CS, Denman SE, Chrimes AF, Muir JG, Berean KJ, Kalantar-Zadeh K, and Gibson PR
- Subjects
- Humans, Fermentation, Colon metabolism, Dietary Fiber metabolism, Fatty Acids, Volatile, Feces microbiology, Diet, Hydrogen analysis, FODMAP Diet
- Abstract
Background: Carbohydrate fermentation plays a pivotal role in maintaining colonic health with excessive proximal and deficient distal fermentation being detrimental., Aims: To utilise telemetric gas- and pH-sensing capsule technologies for defining patterns of regional fermentation following dietary manipulations, alongside conventional techniques of measuring fermentation., Methods: In a double-blind crossover trial, 20 patients with irritable bowel syndrome were fed low FODMAP diets that included no extra fibre (total fibre content 24 g/day), or additional poorly fermented fibre, alone (33 g/day) or with fermentable fibre (45 g/day) for 2 weeks. Plasma and faecal biochemistry, luminal profiles defined by tandem gas- and pH-sensing capsules, and faecal microbiota were assessed., Results: Plasma short-chain fatty acid (SCFA) concentrations (μmol/L) were median (IQR) 121 (100-222) with fibre combination compared with 66 (44-120) with poorly fermented fibre alone (p = 0.028) and 74 (55-125) control (p = 0.069), but no differences in faecal content were observed. Luminal hydrogen concentrations (%), but not pH, were higher in distal colon (mean 4.9 [95% CI: 2.2-7.5]) with fibre combination compared with 1.8 (0.8-2.8) with poorly fermented fibre alone (p = 0.003) and 1.9 (0.7-3.1) control (p = 0.003). Relative abundances of saccharolytic fermentative bacteria were generally higher in association with supplementation with the fibre combination., Conclusions: A modest increase in fermentable plus poorly fermented fibres had minor effects on faecal measures of fermentation, despite increases in plasma SCFA and abundance of fermentative bacteria, but the gas-sensing capsule, not pH-sensing capsule, detected the anticipated propagation of fermentation distally in the colon. The gas-sensing capsule technology provides unique insights into localisation of colonic fermentation., Trial Registration: ACTRN12619000691145., (© 2023 The Authors. Alimentary Pharmacology & Therapeutics published by John Wiley & Sons Ltd.)
- Published
- 2023
- Full Text
- View/download PDF
5. Comparison of gastrointestinal landmarks using the gas-sensing capsule and wireless motility capsule.
- Author
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Thwaites PA, Yao CK, Maggo J, John J, Chrimes AF, Burgell RE, Muir JG, Parker FC, So D, Kalantar-Zadeh K, Gearry RB, Berean KJ, and Gibson PR
- Subjects
- Capsules, Gastrointestinal Motility physiology, Gastrointestinal Transit physiology, Healthy Volunteers, Humans, Capsule Endoscopy methods, Gastrointestinal Diseases
- Abstract
Background: Accurate definition of the gastroduodenal and ileocaecal junctions (GDJ, ICJ) is essential for the measurement of regional transit times., Aims: To compare the assessment of these landmarks using the novel gas-sensing capsule and validated wireless motility capsule (WMC), and to evaluate intra-subject variance in transit times METHODS: Healthy subjects ingested the gas-sensing capsule and WMC tandemly in random order. Inter-observer agreement was evaluated by intra-class correlation coefficient (ICC). Agreement between the paired devices' transit times was assessed using Bland-Altman analysis; coefficient of variation was performed to express intra-individual variance in transit times. Similar analyses were completed with tandemly ingested gas-sensing capsules., Results: The inter-observer agreement for landmarks for both capsules was excellent (mean ICC ≥0.97) in 50 studies. The GDJ was identifiable in 92% of the gas-sensing capsule studies versus 82% of the WMC studies (p = 0.27); the ICJ in 96% versus 84%, respectively (p = 0.11). In the primary cohort (n = 26), median regional transit times differed by less than 6 min between paired capsules. Bland-Altman revealed a bias of -0.12 (95% limits of agreement, -0.94 to 0.70) hours for GDJ and - 0.446 (-2.86 to 2.0) hours for ICJ. Similar results were found in a demographically distinct validation cohort (n = 24). For tandemly ingested gas-sensing capsules, coefficients of variation of transit times were 11%-35%, which were similar to variance between the paired gas-sensing capsule and WMC, as were the biases. The capsules were well tolerated., Conclusions: Key anatomical landmarks are accurately identified with the gas-sensing capsule in healthy individuals. Intra-individual differences in transit times between capsules are probably due to physiological factors. Studies in populations with gastrointestinal diseases are now required., (© 2022 The Authors. Alimentary Pharmacology & Therapeutics published by John Wiley & Sons Ltd.)
- Published
- 2022
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- View/download PDF
6. Fringe analysis approach for imaging surface undulations on technical surfaces.
- Author
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Broadley LH, Chrimes AF, and Mitchell A
- Abstract
Automated defect inspection is becoming increasingly important for advanced manufacturing. The ability to automatically inspect for critical defects early in the production cycle can reduce production costs and resources on unnecessary manufacturing steps. While there are many inspection techniques available, samples from early in a production workflow can prove challenging as they may still have systematic tooling marks, causing preferential scattering and hindering defect extraction. We propose a new imaging technique that exploits the preferential scattering from a technical surface to generate predictable fringe patterns on the sample's surface using only an array of LEDs. The patterns from this adapted fringe projection technique are imaged, and phase shifting algorithms are used to recover surface undulations on the sample. We implement this technique in the context of Hard Disk Drive platters that exhibit tooling marks from the lapping process and show that it is possible to image both highly scattering pits and scratches, as well as slow surface undulations with the same apparatus.
- Published
- 2021
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7. Microfluidic dielectrophoretic cell manipulation towards stable cell contact assemblies.
- Author
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Md Ali MA, Kayani ABA, Yeo LY, Chrimes AF, Ahmad MZ, Ostrikov KK, and Majlis BY
- Subjects
- Cell Survival, Electric Impedance, Electrodes, Equipment Design, Hot Temperature, Yeasts cytology, Cytological Techniques instrumentation, Electrophoresis instrumentation, Lab-On-A-Chip Devices
- Abstract
Cell contact formation, which is the process by which cells are brought into close proximity is an important biotechnological process in cell and molecular biology. Such manipulation is achieved by various means, among which dielectrophoresis (DEP) is widely used due to its simplicity. Here, we show the advantages in the judicious choice of the DEP microelectrode configuration in terms of limiting undesirable effects of dielectric heating on the cells, which could lead to their inactivation or death, as well as the possibility for cell clustering, which is particularly advantageous over the linear cell chain arrangement typically achieved to date with DEP. This study comprises of experimental work as well as mathematical modeling using COMSOL. In particular, we establish the parameters in a capillary-based microfluidic system giving rise to these optimum cell-cell contact configurations, together with the possibility for facilitating other cell manipulations such as spinning and rotation, thus providing useful protocols for application into microfluidic bioparticle manipulation systems for diagnostics, therapeutics or for furthering research in cellular bioelectricity and intercellular interactions.
- Published
- 2018
- Full Text
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8. The safety and sensitivity of a telemetric capsule to monitor gastrointestinal hydrogen production in vivo in healthy subjects: a pilot trial comparison to concurrent breath analysis.
- Author
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Berean KJ, Ha N, Ou JZ, Chrimes AF, Grando D, Yao CK, Muir JG, Ward SA, Burgell RE, Gibson PR, and Kalantar-Zadeh K
- Subjects
- Adolescent, Adult, Breath Tests methods, Endoscopy, Gastrointestinal instrumentation, Endoscopy, Gastrointestinal methods, Female, Gastrointestinal Tract diagnostic imaging, Gastrointestinal Tract metabolism, Healthy Volunteers, Humans, Male, Pilot Projects, Reproducibility of Results, Young Adult, Bacterial Infections diagnosis, Biosensing Techniques instrumentation, Biosensing Techniques methods, Capsule Endoscopy instrumentation, Capsule Endoscopy methods, Gastrointestinal Tract chemistry, Hydrogen analysis, Hydrogen metabolism, Telemetry instrumentation, Telemetry methods
- Abstract
Background: Intestinal gases are currently used for the diagnosis of disorders including small intestinal bacterial overgrowth and carbohydrate malabsorption., Aim: To compare the performance of measuring hydrogen production within the gut directly with the telemetric gas-sensing capsule with that of indirect measurement through breath testing., Methods: Using standard breath testing protocols, the capsules and breath tests were simultaneously evaluated in a single-blinded trial in 12 healthy subjects. Eight received a single dose of 1.25-40 g inulin and four 20 or 40 g glucose. Safety and reliability of the capsules were also assessed., Results: There were no reported adverse events. All capsules were retrieved and operated without failure. Capsule measurements were in agreement with breath test measurements in magnitude but not in timing; minimal hydrogen production was observed after glucose ingestion and capsule measurements correlated with breath hydrogen after ingestion of 40 g inulin. A dose-dependent increase in concentration of hydrogen was observed from the capsule following ingestion of inulin as low as 1.25 g compared with >10 g for breath measurements. Specifically, the capsule measured >3000 times higher concentrations of hydrogen compared to breath tests, resulting in a signal-to-noise ratio of 23.4 for the capsule compared to 4.2 for the breath test., Conclusions: The capsule showed high sensitivity and signal-to-noise ratio in measuring luminal hydrogen concentrations, provided information on the site of intestinal gas production, and demonstrated safety and reliability. The capsule has potential for improving diagnostic precision for disorders such as small intestinal bacterial overgrowth., (© 2018 John Wiley & Sons Ltd.)
- Published
- 2018
- Full Text
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9. Quasi physisorptive two dimensional tungsten oxide nanosheets with extraordinary sensitivity and selectivity to NO 2 .
- Author
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Khan H, Zavabeti A, Wang Y, Harrison CJ, Carey BJ, Mohiuddin M, Chrimes AF, De Castro IA, Zhang BY, Sabri YM, Bhargava SK, Ou JZ, Daeneke T, Russo SP, Li Y, and Kalantar-Zadeh K
- Abstract
Attributing to their distinct thickness and surface dependent physicochemical properties, two dimensional (2D) nanostructures have become an area of increasing interest for interfacial interactions. Effectively, properties such as high surface-to-volume ratio, modulated surface activities and increased control of oxygen vacancies make these types of materials particularly suitable for gas-sensing applications. This work reports a facile wet-chemical synthesis of 2D tungsten oxide nanosheets by sonication of tungsten particles in an acidic environment and thermal annealing thereafter. The resultant product of large nanosheets with intrinsic substoichiometric properties is shown to be highly sensitive and selective to nitrogen dioxide (NO
2 ) gas, which is a major pollutant. The strong synergy between polar NO2 molecules and tungsten oxide surface and also abundance of active surface sites on the nanosheets for molecule interactions contribute to the exceptionally sensitive and selective response. An extraordinary response factor of ∼30 is demonstrated to ultralow 40 parts per billion (ppb) NO2 at a relatively low operating temperature of 150 °C, within the physisorption temperature band for tungsten oxide. Selectivity to NO2 is demonstrated and the theory behind it is discussed. The structural, morphological and compositional characteristics of the synthesised and annealed materials are extensively characterised and electronic band structures are proposed. The demonstrated 2D tungsten oxide based sensing device holds the greatest promise for producing future commercial low-cost, sensitive and selective NO2 gas sensors.- Published
- 2017
- Full Text
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10. A Gallium-Based Magnetocaloric Liquid Metal Ferrofluid.
- Author
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A de Castro I, Chrimes AF, Zavabeti A, Berean KJ, Carey BJ, Zhuang J, Du Y, Dou SX, Suzuki K, Shanks RA, Nixon-Luke R, Bryant G, Khoshmanesh K, Kalantar-Zadeh K, and Daeneke T
- Abstract
We demonstrate a magnetocaloric ferrofluid based on a gadolinium saturated liquid metal matrix, using a gallium-based liquid metal alloy as the solvent and suspension medium. The material is liquid at room temperature, while exhibiting spontaneous magnetization and a large magnetocaloric effect. The magnetic properties were attributed to the formation of gadolinium nanoparticles suspended within the liquid gallium alloy, which acts as a reaction solvent during the nanoparticle synthesis. High nanoparticle weight fractions exceeding 2% could be suspended within the liquid metal matrix. The liquid metal ferrofluid shows promise for magnetocaloric cooling due to its high thermal conductivity and its liquid nature. Magnetic and thermoanalytic characterizations reveal that the developed material remains liquid within the temperature window required for domestic refrigeration purposes, which enables future fluidic magnetocaloric devices. Additionally, the observed formation of nanometer-sized metallic particles within the supersaturated liquid metal solution has general implications for chemical synthesis and provides a new synthetic pathway toward metallic nanoparticles based on highly reactive rare earth metals.
- Published
- 2017
- Full Text
- View/download PDF
11. Ionic imbalance induced self-propulsion of liquid metals.
- Author
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Zavabeti A, Daeneke T, Chrimes AF, O'Mullane AP, Zhen Ou J, Mitchell A, Khoshmanesh K, and Kalantar-Zadeh K
- Abstract
Components with self-propelling abilities are important building blocks of small autonomous systems and the characteristics of liquid metals are capable of fulfilling self-propulsion criteria. To date, there has been no exploration regarding the effect of electrolyte ionic content surrounding a liquid metal for symmetry breaking that generates motion. Here we show the controlled actuation of liquid metal droplets using only the ionic properties of the aqueous electrolyte. We demonstrate that pH or ionic concentration gradients across a liquid metal droplet induce both deformation and surface Marangoni flow. We show that the Lippmann dominated deformation results in maximum velocity for the self-propulsion of liquid metal droplets and illustrate several key applications, which take advantage of such electrolyte-induced motion. With this finding, it is possible to conceive the propulsion of small entities that are constructed and controlled entirely with fluids, progressing towards more advanced soft systems.
- Published
- 2016
- Full Text
- View/download PDF
12. Controlled Electrochemical Deformation of Liquid-Phase Gallium.
- Author
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Chrimes AF, Berean KJ, Mitchell A, Rosengarten G, and Kalantar-zadeh K
- Abstract
Pure gallium is a soft metal with a low temperature melting point of 29.8 °C. This low melting temperature can potentially be employed for creating optical components with changeable configurations on demand by manipulating gallium in its liquid state. Gallium is a smooth and highly reflective metal that can be readily maneuvered using electric fields. These features allow gallium to be used as a reconfigurable optical reflector. This work demonstrates the use of gallium for creating reconfigurable optical reflectors manipulated through the use of electric fields when gallium is in a liquid state. The use of gallium allows the formed structures to be frozen and preserved as long as the temperature of the metal remains below its melting temperature. The lens can be readily reshaped by raising the temperature above the melting point and reapplying an electric field to produce a different curvature of the gallium reflector.
- Published
- 2016
- Full Text
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13. Exfoliation Solvent Dependent Plasmon Resonances in Two-Dimensional Sub-Stoichiometric Molybdenum Oxide Nanoflakes.
- Author
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Alsaif MM, Field MR, Daeneke T, Chrimes AF, Zhang W, Carey BJ, Berean KJ, Walia S, van Embden J, Zhang B, Latham K, Kalantar-Zadeh K, and Ou JZ
- Abstract
Few-layer two-dimensional (2D) molybdenum oxide nanoflakes are exfoliated using a grinding assisted liquid phase sonication exfoliation method. The sonication process is carried out in five different mixtures of water with both aprotic and protic solvents. We found that surface energy and solubility of mixtures play important roles in changing the thickness, lateral dimension, and synthetic yield of the nanoflakes. We demonstrate an increase in proton intercalation in 2D nanoflakes upon simulated solar light exposure. This results in substoichiometric flakes and a subsequent enhancement in free electron concentrations, producing plasmon resonances. Two plasmon resonance peaks associated with the thickness and the lateral dimension axes are observable in the samples, in which the plasmonic peak positions could be tuned by the choice of the solvent in exfoliating 2D molybdenum oxide. The extinction coefficients of the plasmonic absorption bands of 2D molybdenum oxide nanoflakes in all samples are found to be high (ε > 10(9) L mol(-1) cm(-1)). It is expected that the tunable plasmon resonances of 2D molybdenum oxide nanoflakes presented in this work can be used in future electronic, optical, and sensing devices.
- Published
- 2016
- Full Text
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14. Acoustically-Driven Trion and Exciton Modulation in Piezoelectric Two-Dimensional MoS2.
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Rezk AR, Carey B, Chrimes AF, Lau DW, Gibson BC, Zheng C, Fuhrer MS, Yeo LY, and Kalantar-Zadeh K
- Abstract
By exploiting the very recent discovery of the piezoelectricity in odd-numbered layers of two-dimensional molybdenum disulfide (MoS2), we show the possibility of reversibly tuning the photoluminescence of single and odd-numbered multilayered MoS2 using high frequency sound wave coupling. We observe a strong quenching in the photoluminescence associated with the dissociation and spatial separation of electrons-holes quasi-particles at low applied acoustic powers. At the same applied powers, we note a relative preference for ionization of trions into excitons. This work also constitutes the first visual presentation of the surface displacement in one-layered MoS2 using laser Doppler vibrometry. Such observations are associated with the acoustically generated electric field arising from the piezoelectric nature of MoS2 for odd-numbered layers. At larger applied powers, the thermal effect dominates the behavior of the two-dimensional flakes. Altogether, the work reveals several key fundamentals governing acousto-optic properties of odd-layered MoS2 that can be implemented in future optical and electronic systems.
- Published
- 2016
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15. Electronic Tuning of 2D MoS2 through Surface Functionalization.
- Author
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Nguyen EP, Carey BJ, Ou JZ, van Embden J, Gaspera ED, Chrimes AF, Spencer MJ, Zhuiykov S, Kalantar-Zadeh K, and Daeneke T
- Abstract
The electronic properties of thiol-functionalized 2D MoS2 nanosheets are investigated. Shifts in the valence and conduction bands and Fermi levels are observed while bandgaps remain unaffected. These findings allow the tuning of energy barriers between 2D MoS2 and other materials, which can lead to improved control over 2D MoS2 -based electronic and optical devices and catalysts., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2015
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16. Physisorption-Based Charge Transfer in Two-Dimensional SnS2 for Selective and Reversible NO2 Gas Sensing.
- Author
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Ou JZ, Ge W, Carey B, Daeneke T, Rotbart A, Shan W, Wang Y, Fu Z, Chrimes AF, Wlodarski W, Russo SP, Li YX, and Kalantar-Zadeh K
- Abstract
Nitrogen dioxide (NO2) is a gas species that plays an important role in certain industrial, farming, and healthcare sectors. However, there are still significant challenges for NO2 sensing at low detection limits, especially in the presence of other interfering gases. The NO2 selectivity of current gas-sensing technologies is significantly traded-off with their sensitivity and reversibility as well as fabrication and operating costs. In this work, we present an important progress for selective and reversible NO2 sensing by demonstrating an economical sensing platform based on the charge transfer between physisorbed NO2 gas molecules and two-dimensional (2D) tin disulfide (SnS2) flakes at low operating temperatures. The device shows high sensitivity and superior selectivity to NO2 at operating temperatures of less than 160 °C, which are well below those of chemisorptive and ion conductive NO2 sensors with much poorer selectivity. At the same time, excellent reversibility of the sensor is demonstrated, which has rarely been observed in other 2D material counterparts. Such impressive features originate from the planar morphology of 2D SnS2 as well as unique physical affinity and favorable electronic band positions of this material that facilitate the NO2 physisorption and charge transfer at parts per billion levels. The 2D SnS2-based sensor provides a real solution for low-cost and selective NO2 gas sensing.
- Published
- 2015
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17. Dielectrophoretically controlled Fresnel zone plate.
- Author
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Chrimes AF, Khodasevych I, Mitchell A, Rosengarten G, and Kalantar-zadeh K
- Abstract
Switchability is a highly sought after feature for planar optical systems. Suspensions of nanomaterials can be used for generating controllable changes in such systems. We report a planar diffractive microfluidic lens which integrates controlled dielectrophoresis (DEP) for trapping suspended nanomaterials. Silicon and tungsten oxide nanoparticle suspensions are used. These nanomaterials are trapped in such a way as to form alternating opaque and transparent rings using the DEP forces on demand. These rings form a planar diffractive Fresnel zone plate to focus the incident light. The Fresnel zone plate is tuned for the visible light region and the lens can be turned on (DEP applied) or off (DEP removed) in a controlled manner. This proof of concept demonstration can be further expanded for a variety of switchable optical devices and can be integrated with lab-on-a-chip and optofluidic devices.
- Published
- 2015
- Full Text
- View/download PDF
18. Plasmon resonances of highly doped two-dimensional MoS₂.
- Author
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Wang Y, Ou JZ, Chrimes AF, Carey BJ, Daeneke T, Alsaif MM, Mortazavi M, Zhuiykov S, Medhekar N, Bhaskaran M, Friend JR, Strano MS, and Kalantar-Zadeh K
- Subjects
- Disulfides chemistry, Molybdenum chemistry, Surface Plasmon Resonance
- Abstract
The exhibition of plasmon resonances in two-dimensional (2D) semiconductor compounds is desirable for many applications. Here, by electrochemically intercalating lithium into 2D molybdenum disulfide (MoS2) nanoflakes, plasmon resonances in the visible and near UV wavelength ranges are achieved. These plasmon resonances are controlled by the high doping level of the nanoflakes after the intercalation, producing two distinct resonance peak areas based on the crystal arrangements. The system is also benchmarked for biosensing using bovine serum albumin. This work provides a foundation for developing future 2D MoS2 based biological and optical units.
- Published
- 2015
- Full Text
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19. Liquid metal/metal oxide frameworks with incorporated Ga2O3 for photocatalysis.
- Author
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Zhang W, Naidu BS, Ou JZ, O'Mullane AP, Chrimes AF, Carey BJ, Wang Y, Tang SY, Sivan V, Mitchell A, Bhargava SK, and Kalantar-Zadeh K
- Abstract
Solvothermally synthesized Ga2O3 nanoparticles are incorporated into liquid metal/metal oxide (LM/MO) frameworks in order to form enhanced photocatalytic systems. The LM/MO frameworks, both with and without incorporated Ga2O3 nanoparticles, show photocatalytic activity due to a plasmonic effect where performance is related to the loading of Ga2O3 nanoparticles. Optimum photocatalytic efficiency is obtained with 1 wt % incorporation of Ga2O3 nanoparticles. This can be attributed to the sub-bandgap states of LM/MO frameworks, contributing to pseudo-ohmic contacts which reduce the free carrier injection barrier to Ga2O3.
- Published
- 2015
- Full Text
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20. Substoichiometric two-dimensional molybdenum oxide flakes: a plasmonic gas sensing platform.
- Author
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Alsaif MM, Field MR, Murdoch BJ, Daeneke T, Latham K, Chrimes AF, Zoolfakar AS, Russo SP, Ou JZ, and Kalantar-zadeh K
- Abstract
Two-dimensional (2D) molybdenum oxides at their various stoichiometries are promising candidates for generating plasmon resonances in visible light range. Herein, we demonstrate plasmonic 2D molybdenum oxide flakes for gas sensing applications, in which hydrogen (H2) is selected as a model gas. The 2D molybdenum oxide flakes are obtained using a grinding-assisted liquid exfoliation method and exposed to simulated sunlight to acquire its substoichiometric quasi-metallic form. After the exposure to H2 gas molecules, the quasi-metallic molybdenum oxide flakes are partially transformed into semiconducting states, thus gradually losing their plasmonic properties. The novel 2D plasmonic sensing platform is tested using different concentrations of H2 gas at various operating temperatures to comprehensively assess its sensing performance. The presented 2D plasmonic system offers great opportunities for future sensing and optical applications.
- Published
- 2014
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21. Ion-driven photoluminescence modulation of quasi-two-dimensional MoS2 nanoflakes for applications in biological systems.
- Author
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Ou JZ, Chrimes AF, Wang Y, Tang SY, Strano MS, and Kalantar-zadeh K
- Subjects
- Adsorption, Disulfides radiation effects, Glucose chemistry, Ions, Molybdenum radiation effects, Nanoparticles radiation effects, Particle Size, Biosensing Techniques methods, Disulfides chemistry, Glucose analysis, Glucose Oxidase chemistry, Luminescent Measurements methods, Molybdenum chemistry, Nanoparticles chemistry
- Abstract
Quasi-two-dimensional (quasi-2D) molybdenum disulfide (MoS2) is a photoluminescence (PL) material with unique properties. The recent demonstration of its PL, controlled by the intercalation of positive ions, can lead to many opportunities for employing this quasi-2D material in ion-related biological applications. Here, we present two representative models of biological systems that incorporate the ion-controlled PL of quasi-2D MoS2 nanoflakes. The ion exchange behaviors of these two models are investigated to reveal enzymatic activities and cell viabilities. While the ion intercalation of MoS2 in enzymatic activities is enabled via an external applied voltage, the intercalation of ions in cell viability investigations occurs in the presence of the intrinsic cell membrane potential.
- Published
- 2014
- Full Text
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22. Electrochemical control of photoluminescence in two-dimensional MoS(2) nanoflakes.
- Author
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Wang Y, Ou JZ, Balendhran S, Chrimes AF, Mortazavi M, Yao DD, Field MR, Latham K, Bansal V, Friend JR, Zhuiykov S, Medhekar NV, Strano MS, and Kalantar-Zadeh K
- Subjects
- Biosensing Techniques, Crystallization, Disulfides chemistry, Electronics, Ions, Luminescence, Materials Testing, Optics and Photonics, Particle Size, Semiconductors, Software, Spectrum Analysis, Raman, Surface Properties, Electrochemistry methods, Molybdenum chemistry, Nanostructures chemistry
- Abstract
Two-dimensional (2D) transition metal dichalcogenide semiconductors offer unique electronic and optical properties, which are significantly different from their bulk counterparts. It is known that the electronic structure of 2D MoS2, which is the most popular member of the family, depends on the number of layers. Its electronic structure alters dramatically at near atomically thin morphologies, producing strong photoluminescence (PL). Developing processes for controlling the 2D MoS2 PL is essential to efficiently harness many of its optical capabilities. So far, it has been shown that this PL can be electrically or mechanically gated. Here, we introduce an electrochemical approach to actively control the PL of liquid-phase-exfoliated 2D MoS2 nanoflakes by manipulating the amount of intercalated ions including Li(+), Na(+), and K(+) into and out of the 2D crystal structure. These ions are selected as they are crucial components in many bioprocesses. We show that this controlled intercalation allows for large PL modulations. The introduced electrochemically controlled PL will find significant applications in future chemical and bio-optical sensors as well as optical modulators/switches.
- Published
- 2013
- Full Text
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23. In situ SERS probing of nano-silver coated individual yeast cells.
- Author
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Chrimes AF, Khoshmanesh K, Tang SY, Wood BR, Stoddart PR, Collins SS, Mitchell A, and Kalantar-zadeh K
- Subjects
- Equipment Design, Metal Nanoparticles chemistry, Metal Nanoparticles ultrastructure, Principal Component Analysis, Saccharomyces cerevisiae metabolism, Silver chemistry, Microfluidic Analytical Techniques instrumentation, Saccharomyces cerevisiae cytology, Spectrum Analysis, Raman instrumentation
- Abstract
For understanding cells functionalities and their communications, there is a need for highly sensitive cell analysis platforms capable of assessing non-specific chemicals on the surface and in the vicinity of cells. We report a microfluidic system integrating dielectrophoresis and surface enhanced Raman scattering (SERS) for the trapping and real time monitoring of cell functions in isolated and grouped cell clusters. Yeast cells are coated with silver nanoparticles to enable highly sensitive SERS analysis. The SERS responses of cells are examined under various conditions: live vs. dead and isolated vs. grouped. This work illustrates the feasibility of the system for in situ cell monitoring and analysis of secreted chemicals during their growth, metabolism, proliferation and apoptosis., (Copyright © 2013 Elsevier B.V. All rights reserved.)
- Published
- 2013
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24. Microfluidics and Raman microscopy: current applications and future challenges.
- Author
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Chrimes AF, Khoshmanesh K, Stoddart PR, Mitchell A, and Kalantar-Zadeh K
- Subjects
- Animals, Humans, Microfluidics trends, Microscopy trends, Microfluidics methods, Microscopy methods, Spectrum Analysis, Raman methods
- Abstract
Raman microscopy systems are becoming increasingly widespread and accessible for characterising chemical species. Microfluidic systems are also progressively finding their way into real world applications. Therefore, it is anticipated that the integration of Raman systems with microfluidics will become increasingly attractive and practical. This review aims to provide an overview of Raman microscopy-microfluidics integrated systems for researchers who are actively interested in utilising these tools. The fundamental principles and application strengths of Raman microscopy are discussed in the context of microfluidics. Various configurations of microfluidics that incorporate Raman microscopy methods are presented, with applications highlighted. Data analysis methods are discussed, with a focus on assisting the interpretation of Raman-microfluidics data from complex samples. Finally, possible future directions of Raman-microfluidic systems are presented.
- Published
- 2013
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25. Thermal analysis of nanofluids in microfluidics using an infrared camera.
- Author
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Yi P, Kayani AA, Chrimes AF, Ghorbani K, Nahavandi S, Kalantar-zadeh K, and Khoshmanesh K
- Abstract
We present the thermal analysis of liquid containing Al(2)O(3) nanoparticles in a microfluidic platform using an infrared camera. The small dimensions of the microchannel along with the low flow rates (less than 120 μl min(-1)) provide very low Reynolds numbers of less than 17.5, reflecting practical parameters for a microfluidic cooling platform. The heat analysis of nanofluids has never been investigated in such a regime, due to the deficiencies of conventional thermal measurement systems. The infrared camera allows non-contact, three dimensional and high resolution capability for temperature profiling. The system was studied at different w/w concentrations of thermally conductive Al(2)O(3) nanoparticles and the experiments were in excellent agreement with the computational fluid dynamics (CFD) simulations.
- Published
- 2012
- Full Text
- View/download PDF
26. Dynamic manipulation of modes in an optical waveguide using dielectrophoresis.
- Author
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Kayani AA, Khoshmanesh K, Nguyen TG, Kostovski G, Chrimes AF, Nasabi M, Heller DA, Mitchell A, and Kalantar-zadeh K
- Subjects
- Equipment Design, Hydrodynamics, Light, Refractometry instrumentation, Electrophoresis instrumentation, Microfluidic Analytical Techniques instrumentation, Optical Devices
- Abstract
The emergence of optofluidics has brought a high degree of tuneability and reconfigurability to optical devices. These possibilities are provided by characteristics of fluids including mobility, wide range of index modulation, and abrupt interfaces that can be easily reshaped. In this work, we created a new class of optofluidic waveguides, in which suspended mesoparticles were employed to greatly enhance the flexibility of the system. We demonstrated tuneable quasi single mode waveguides using spatially controllable mesoparticles in optofluidics. The coupling of waveguiding modes into the assembly of mesoparticles produces strong interactions and resonant conditions, which promote the transitions of the waveguiding modes. The modal response of the system depends on the distribution of packed particles above the polymeric rib waveguide which can be readily controlled under the appropriate combination of dielectrophoresis and hydrodynamic forces., (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2012
- Full Text
- View/download PDF
27. Active control of silver nanoparticles spacing using dielectrophoresis for surface-enhanced Raman scattering.
- Author
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Chrimes AF, Khoshmanesh K, Stoddart PR, Kayani AA, Mitchell A, Daima H, Bansal V, and Kalantar-zadeh K
- Subjects
- Bacillus anthracis isolation & purification, Equipment Design, Picolinic Acids, Sensitivity and Specificity, Electrophoresis, Microchip instrumentation, Nanoparticles chemistry, Pyridines analysis, Silver chemistry, Spectrum Analysis, Raman instrumentation
- Abstract
We demonstrate an active microfluidic platform that integrates dielectrophoresis for the control of silver nanoparticles spacing, as they flow in a liquid channel. By careful control of the nanoparticles spacing, we can effectively increase the surface-enhanced Raman scattering (SERS) signal intensity based on augmenting the number of SERS-active hot-spots, while avoiding irreversible aggregation of the particles. The system is benchmarked using dipicolinate (2,6-pyridinedicarboxylic acid) (DPA), which is a biomarker of Bacillus anthracis. The validity of the results is discussed using several complementing characterization scenarios.
- Published
- 2012
- Full Text
- View/download PDF
28. Dielectrophoresis-Raman spectroscopy system for analysing suspended nanoparticles.
- Author
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Chrimes AF, Kayani AA, Khoshmanesh K, Stoddart PR, Mulvaney P, Mitchell A, and Kalantar-Zadeh K
- Subjects
- Electric Impedance, Oxides analysis, Oxides chemistry, Polystyrenes analysis, Polystyrenes chemistry, Suspensions, Tungsten analysis, Tungsten chemistry, Microfluidic Analytical Techniques instrumentation, Nanoparticles analysis, Nanoparticles chemistry, Spectrum Analysis, Raman instrumentation
- Abstract
A microfluidic dielectrophoresis platform consisting of curved microelectrodes was developed and integrated with a Raman spectroscopy system. The electrodes were patterned on a quartz substrate, which has insignificant Raman response, and integrated with a microfluidic channel that was imprinted in poly-dimethylsiloxane (PDMS). We will show that this novel integrated system can be efficiently used for the determination of suspended particle types and the direct mapping of their spatial concentrations. We will also illustrate the system's unique advantages over conventional optical systems. Nanoparticles of tungsten trioxide (WO(3)) and polystyrene were used in the investigations, as they are Raman active and can be homogeneously suspended in water.
- Published
- 2011
- Full Text
- View/download PDF
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