ORCID Profile
0000-0002-6250-7582
Current Organisation
University of Cambridge
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Publisher: American Chemical Society (ACS)
Date: 13-07-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8CS00084K
Abstract: Functional printing of graphene and related two-dimensional materials provides an ideal platform for next generation disruptive technologies and applications.
Publisher: Springer Science and Business Media LLC
Date: 24-05-2022
DOI: 10.1038/S41699-022-00312-W
Abstract: The surface porosity of graphene-based aerogels strongly influences their performance in applications involving mass transfer. However, the factors determining the surface porosities are not well-understood, hindering their application-specific optimisation. Here, through experiments and hydrodynamic simulations, we show that the high shear stress during the graphene-based aerogel fabrication process via 3D printing leads to a non-porous surface. Conversely, crosslinking of the sheets hinders flake alignment caused by shearing, resulting in a porous surface. Our findings enable fine control of surface porosity of printed graphene-oxide aerogels (GOA) through regulation of the crosslinking agents and shear stress. Using this strategy, we demonstrate the performance advantages of GOA with porous surface over their non-porous counterpart in dye adsorption, underscoring the importance of surface porosity in certain application scenarios.
Publisher: Wiley
Date: 04-12-2021
Abstract: Flexographic printing is promising for large‐area electronics due to high print‐speed and roll‐to‐roll capability. There have been recent attempts in using graphene as an active pigment in inks, most notably for slower techniques such as inkjet and screen printing. However, formulation of graphene‐enhanced inks for high‐speed printing and its effect on key metrics have never been investigated. Herein, graphene nanoplatelets (GPs) are incorporated to a conductive flexographic ink without compromising the rheological properties. An industrial scale at 100 m min −1 is printed on paper and polyethylene terephthalate (PET) substrates using a commercial flexographic press, and statistical performance variations are investigated across entire print runs. It is shown that GP‐incorporation improves sheet‐resistance ( R s ) and uniformity, with up to 54% improvement in average R s and 45% improvement in the standard‐deviation on PET. The adhesion on both the substrates improves with GP‐incorporation, as verified by tape/crosshatch tests. The durability of GP‐enhanced s les is probed with a 1000 cyclic bend‐test, with 0.31% average variation in resistance in the flat state on PET between the first and last 100 bends, exhibiting a robust print. The statistically scalable results show that GP‐incorporation offers a cost‐performance advantage for flexographic printing of large‐area conductive patterns without modifications to traditional high‐speed graphics printing presses.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 21-10-2022
Abstract: Miniaturized computational spectrometers, which can obtain incident spectra using a combination of device spectral responses and reconstruction algorithms, are essential for on-chip and implantable applications. Highly sensitive spectral measurement using a single detector allows the footprints of such spectrometers to be scaled down while achieving spectral resolution approaching that of benchtop systems. We report a high-performance computational spectrometer based on a single van der Waals junction with an electrically tunable transport-mediated spectral response. We achieve high peak wavelength accuracy (∼0.36 nanometers), high spectral resolution (∼3 nanometers), broad operation bandwidth (from ∼405 to 845 nanometers), and proof-of-concept spectral imaging. Our approach provides a route toward ultraminiaturization and offers unprecedented performance in accuracy, resolution, and operation bandwidth for single-detector computational spectrometers.
Publisher: Research Square Platform LLC
Date: 12-09-2022
DOI: 10.21203/RS.3.RS-2039368/V1
Abstract: Materials with programmable conductivity and stiffness offer new design opportunities for next-generation engineered systems in soft robotics and wearable devices. However, existing approaches fail to harness variable electrical and mechanical properties synergistically, and lack the ability to self-respond to environmental changes. We report an electro-mechano responsive Field’s metal hybrid elastomer (FMHE) exhibiting variable and tuneable conductivity, strain sensitivity, and stiffness. By synergistically harnessing these properties, we demonstrate two applications with over an order of magnitude performance improvement compared to state-of-the-art, including a self-triggered multi-axis compliance compensator for robotic manipulators, and a resettable, highly compact, and fast current-limiting fuse with adjustable fusing current. We envisage that the extraordinary electromechanical properties of our hybrid elastomer will bring significant advancements in resilient robotic systems, intelligent instruments, and flexible electronics.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9CS00459A
Abstract: This review presents the recent development of printed gas sensors based on functional inks.
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7NR09660G
Abstract: Oxygen self-doped CNO- x with tunable electronic band structure demonstrates unprecedentedly enhanced photodegradation of RhB and photocatalytic H 2 production with excellent stability under visible light.
Publisher: American Chemical Society (ACS)
Date: 09-08-2019
Abstract: As an ideal miniaturized light source, wavelength-tunable nanolasers capable of emitting a wide spectrum stimulate intense interests for on-chip optoelectronics, optical communications, and spectroscopy. However, realization of such devices remains a major challenge because of extreme difficulties in achieving continuously reversibly tunable gain media and high quality (Q)-factor resonators on the nanoscale simultaneously. Here, exploiting single bandgap-graded CdSSe NWs and a Fabry-Pérot/whispering gallery mode (FP/WGM) coupling cavity, a free-standing fiber-integrated reversibly wavelength-tunable nanolaser covering a 42 nm wide spectrum at room temperature with high stability and reproducibility is demonstrated. In addition, a 1.13 nm tuning spectral resolution is realized. The substrate-free device design enables integration in optical fiber communications and information. With reversible and wide, continuous tunability of emission color and precise control per step, our work demonstrates a general approach to nanocavity coupling affording high Q-factors, enabling an ideal miniaturized module for a broad range of applications in optics and optoelectronics, with optical fiber integration.
Publisher: Elsevier BV
Date: 10-2020
Publisher: American Association for the Advancement of Science (AAAS)
Date: 29-01-2021
Abstract: Optical spectroscopy is a widely used characterization tool in industrial and research laboratory settings for chemical fingerprinting and analysis. High-end spectrometers are typically benchtop based with bulky optical components, moving parts, and long path lengths, and they can deliver a wealth of information with ultrahigh precision and bandwidth. There is, however, a drive toward miniaturization of spectrometers, in which concepts in nanophotonics are used to control light on much smaller scales. Yang et al. reviewed recent developments in spectrometry systems, including various fabrication approaches of nanophotonics systems and the software that computationally determines the spectra, that strive to shrink their footprint and open up applications in portable spectroscopy. Science , this issue p. eabe0722
Publisher: American Association for the Advancement of Science (AAAS)
Date: 27-01-2023
Abstract: Materials with programmable conductivity and stiffness offer new design opportunities for next-generation engineered systems in soft robotics and electronic devices. However, existing approaches fail to harness variable electrical and mechanical properties synergistically and lack the ability to self-respond to environmental changes. We report an electro-mechano responsive Field’s metal hybrid elastomer exhibiting variable and tunable conductivity, strain sensitivity, and stiffness. By synergistically harnessing these properties, we demonstrate two applications with over an order of magnitude performance improvement compared to state-of-the-art, including a self-triggered multiaxis compliance compensator for robotic manipulators, and a resettable, highly compact, and fast current-limiting fuse with an adjustable fusing current. We envisage that the extraordinary electromechanical properties of our hybrid elastomer will bring substantial advancements in resilient robotic systems, intelligent instruments, and flexible electronics.
Publisher: Wiley
Date: 08-07-2019
Publisher: Research Square Platform LLC
Date: 09-12-2022
DOI: 10.21203/RS.3.RS-2283040/V1
Abstract: Generation of electricity from flowing salt water is extremely attractive as the resources are abundant and green. We propose a generator to harvest DC electricity from flowing ionic solution. The device consists of a substrate with fixed surface charges, a top electrode and a bottom electrode separated with a distance. The electrostatic field originated from the surface charges separates charges of opposite polarities in the solution, while the flow directs the charges to different electrodes in a closed circuit. By utilizing ultrahigh charge density of ferroelectric substrate and ionic solution, the device produces pulsed DC output for droplets and constant current for continuous flow. The output could be greatly enhanced by using substrates with high surface charge densities and high ion concentration solutions. It could also be scaled up by connecting the devices in series or parallel. This work provides a new strategy to harvest low hydrodynamic energy from sea.
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8TA07662F
Abstract: Embedding Se clusters in nitrogen-doped hierarchically radial-structured microporous carbon for Na–Se batteries.
Publisher: Wiley
Date: 02-06-2020
Publisher: American Association for the Advancement of Science (AAAS)
Date: 14-08-2020
Abstract: A binary solvent ink exploiting solutal Marangoni flows to suppress the coffee-ring effect for uniform printing of 2D crystals.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 11-2019
Abstract: Photoactivating oxygen dangling bonds on tapered micro/nanofibers enhances monolayer photoluminescence quantum yields.
Publisher: American Chemical Society (ACS)
Date: 26-06-2022
Abstract: The triboelectric effect occurs when two dissimilar materials are in physical contact, attributed to the combination of contact electrification (CE) and electrostatic induction. It has been extensively explored for the development of high-performance triboelectric nanogenerators (TENGs). In this paper, we report on, besides the CE-related charge generation, an additional charge generation phenomenon associated with the modulation of the p-n junction when two semiconductor materials [methylammonium lead iodide (MAPI) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)] are put in contact and separated dynamically. The electrical outputs generated by the CE effect are determined by the surface potential difference between the two friction materials, while the ones induced by the p-n junction modulation are determined by the dynamic variations in the depletion widths of the two semiconductor friction materials. The outputs generated by the CE effect and the p-n junction effect are well separated in time scale the p-n junction modulation contributes ∼20% of the total charge generated and could be varied by changing the chemical composition of the semiconductors. The results may provide an alternative method for the development of high-performance TENGs by utilizing this additional p-n junction modulation effect.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/C9CS00757A
Abstract: A rapidly growing interdisciplinary research area combining aerogel and printing technologies that began only five years ago has been comprehensively reviewed.
Publisher: Springer Science and Business Media LLC
Date: 27-07-2023
Publisher: American Association for the Advancement of Science (AAAS)
Date: 18-11-2022
Abstract: By simultaneously transducing and lifying, transistors offer advantages over simpler, electrode-based transducers in electrochemical biosensors. However, transistor-based biosensors typically use static (i.e., DC) operation modes that are poorly suited for sensor architectures relying on the modulation of charge transfer kinetics to signal analyte binding. Thus motivated, here, we translate the AC “pulsed potential” approach typically used with electrochemical aptamer-based (EAB) sensors to an organic electrochemical transistor (OECT). Specifically, by applying a linearly sweeping square-wave potential to an aptamer-functionalized gate electrode, we produce current modulation across the transistor channel two orders of magnitude larger than seen for the equivalent, electrode-based biosensor. Unlike traditional EAB sensors, our aptamer-based OECT (AB-OECT) sensors critically maintain output current even with miniaturization. The pulsed transistor operation demonstrated here could be applied generally to sensors relying on kinetics-based signaling, expanding opportunities for noninvasive and high spatial resolution biosensing.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 09-12-2022
Abstract: The ever-growing demand for faster and more efficient data transfer and processing has brought optical computation strategies to the forefront of research in next-generation computing. Here, we report a universal computing approach with the chirality degree of freedom. By exploiting the crystal symmetry–enabled well-known chiral selection rules, we demonstrate the viability of the concept in bulk silica crystals and atomically thin semiconductors and create ultrafast ( -fs) all-optical chirality logic gates (XNOR, NOR, AND, XOR, OR, and NAND) and a half adder. We also validate the unique advantages of chirality gates by realizing multiple gates with simultaneous operation in a single device and electrical control. Our first demonstrations of logic gates using chiral selection rules suggest that optical chirality could provide a powerful degree of freedom for future optical computing.
Publisher: Optica Publishing Group
Date: 24-02-2020
DOI: 10.1364/OE.385142
Abstract: We numerically and experimentally demonstrate the generation of broad bandwidth mode-locked dual-wavelength pulses with erse-pattern from a dispersion managed erbium-doped (Er-doped) fiber laser. The two-peak gain profile of the Er-doped fiber is shown to have advantages in achieving broadband dual-wavelength pulses compared to a comb filter in our cavity. Our obtained bandwidths of 24 nm and 11.5 nm represent the broadest achieved in an Er-doped dual-wavelength fiber laser to date. In addition, the weak third-order dispersion (TOD) of the fibers facilitates two dispersion-pattern pulses (one stretched pulse and one dissipative soliton) generated in the near zero dispersion regime. Our results provide a convenient, effective way to obtain such sources for potential applications, such as in dual-comb metrology and multicolor pulses in nonlinear microscopy.
Publisher: Optica Publishing Group
Date: 27-10-2020
DOI: 10.1364/OE.403530
Abstract: We demonstrate an all-fiber, thulium-doped, mode-locked laser using a black phosphorus (BP) saturable absorber (SA). The BP-SA, exhibiting strong nonlinear response, is fabricated by inkjet printing. The oscillator generates self-starting 139 fs dispersion-managed soliton pulses centered at 1859nm with 55.6 nm spectral bandwidth. This is the shortest pulse duration and widest spectral bandwidth achieved directly from an all-fiber thulium-doped fiber laser mode-locked with a nanomaterial saturable absorber to date. Our findings demonstrate the applicability of BP for femtosecond pulse generation at 2 µm spectral region.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 06-09-2019
Abstract: Spectrometers with ever-smaller footprints are sought after for a wide range of applications in which minimized size and weight are paramount, including emerging in situ characterization techniques. We report on an ultracompact microspectrometer design based on a single compositionally engineered nanowire. This platform is independent of the complex optical components or cavities that tend to constrain further miniaturization of current systems. We show that incident spectra can be computationally reconstructed from the different spectral response functions and measured photocurrents along the length of the nanowire. Our devices are capable of accurate, visible-range monochromatic and broadband light reconstruction, as well as spectral imaging from centimeter-scale focal planes down to lensless, single-cell-scale in situ mapping.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Tawfique Hasan.