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Journal articleDong X, Dong J, Yetisen AK, et al., 2019,
Characterization and layer thickness mapping of two-dimensional MoS2 flakes via hyperspectral line-scanning microscopy
, APPLIED PHYSICS EXPRESS, Vol: 12, ISSN: 1882-0778 -
Journal articleAlQattan B, Benton D, Yetisen AK, et al., 2019,
Conformable Holographic Photonic Ink Sensors Based on Adhesive Tapes for Strain Measurements.
, ACS Appl Mater InterfacesBuildings, bridges, and aircrafts are frequently exposed to fluctuation loads, which could start with a fine crack that instantly leads to unpredictable structure failures. The stationary strain sensors can be utilized, but they are costly and only detect limited deformation forms and sizes. Here, we fabricated photonic strain sensors on adhesive tapes, which can provide real-time monitoring of irregular surfaces. Holographic interference patterning was used to produce nonlinear curved nanostructures of one dimensional (1D) (900 nm × 880 nm) and two dimensional (2D) from a black dye film on a robust uniform adhesive layer and heat resistance tape. The patterned structure of the black dye was stable in broad pH environments. Diffracted light from the curved nanostructure detected the signal during structural damage, a shift or material tear of 5 με at less than 1.3 N cm-2. Additionally, the 2D nanostructure detected a surface change from x or y axis. Tilting the 1D structure within a range of 0.3° to 14.2° provided visible wavelength changes under broadband light to reveal early deflection signs. The curved nanopatterns could be also used for transferable holographic symbol design. Photonic nanopatterns on an adhesive tape could be used as a rapid response, conformable, lightweight, and low-cost dynamic strain sensor.
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Journal articleMoreddu R, Vigolo D, Yetisen AK, 2019,
Contact Lens Technology: From Fundamentals to Applications.
, Adv Healthc Mater, Vol: 8, Pages: e1900368-e1900368Contact lenses are ocular prosthetic devices used by over 150 million people worldwide. Primary applications of contact lenses include vision correction, therapeutics, and cosmetics. Contact lens materials have significantly evolved over time to minimize adverse effects associated with contact lens wearing, to maintain a regular corneal metabolism, and to preserve tear film stability. This article encompasses contact lens technology, including materials, chemical and physical properties, manufacturing processes, microbial contamination, and ocular complications. The function and the composition of the tear fluid are discussed to assess its potential as a diagnostic media. The regulatory standards of contact lens devices with regard to biocompatibility and contact lens market are presented. Future prospects in contact lens technology are evaluated, with particular interest given to theranostic applications for in situ continuous monitoring the ocular physiology.
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Journal articleYetisen AK, Moreddu R, Seifi S, et al., 2019,
Dermal tattoo biosensors for colorimetric metabolite detection.
, Angewandte Chemie International Edition, Vol: 58, Pages: 10506-10513, ISSN: 1433-7851Tattooing is a ubiquitous body modification involving the injection of ink and/or dye pigments into the dermis. Biosensors in the form of tattoos can be used to monitor metabolites in interstitial fluid. Here, minimally invasive, injectable dermal biosensors were developed for measuring pH, glucose, and albumin concentrations. The dermal pH sensor was based on methyl red, bromothymol blue, and phenolphthalein, which responded to a pH range from 5.0 to 9.0. The dermal glucose sensor consisted of glucose oxidase, 3,3',5,5'-tetramethylbenzidine, and peroxidase that detected concentrations up to 50.0 mmol L-1 . The dermal albumin sensor consisted of 3',3'',5',5''-tetrachlorophenol-3,4,5,6-tetrabromosulfophthalein to measure concentrations up to 5.0 g L-1 . The sensors were multiplexed in ex vivo skin tissue and quantitative readouts were obtained using a smartphone camera. These sensors can be used to manage of acid-base homeostasis, diabetes, and liver failure in point-of-care settings.
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Journal articleJiang N, Ahmed R, Damayantharan M, et al., 2019,
Lateral and Vertical Flow Assays for Point-of-Care Diagnostics
, ADVANCED HEALTHCARE MATERIALS, Vol: 8, ISSN: 2192-2640 -
Journal articleElsherif M, Hassan MU, Yetisen AK, et al., 2019,
Hydrogel optical fibers for continuous glucose monitoring
, BIOSENSORS & BIOELECTRONICS, Vol: 137, Pages: 25-32, ISSN: 0956-5663- Author Web Link
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- Citations: 40
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Journal articleElsherif M, Moreddu R, Hassan MU, et al., 2019,
Real-time optical fiber sensors based on light diffusing microlens arrays
, LAB ON A CHIP, Vol: 19, Pages: 2060-2070, ISSN: 1473-0197 -
PatentYetisen AK, 2019,
Stent Using Wireless Transmitted Power and External Operating Apparatus Thereof
The present invention relates to a stent using wirelessly transmitted power, and to an external driving device thereof. To this end, a stent is provided with: a power receiving part wirelessly receiving power from the outside; a power storing part storing the power; a second communicating part receiving a control command from the outside; an electrical stimulation part generating electrical stimulation by using the power; a photosensitizer coated onto a stent; an LED illuminating the vicinity of the stent; and a second control part controlling the heat-generating stent on the basis of the control command.
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Journal articleMuck JE, Unal B, Butt H, et al., 2019,
Market and Patent Analyses of Wearables in Medicine
, TRENDS IN BIOTECHNOLOGY, Vol: 37, Pages: 563-566, ISSN: 0167-7799- Author Web Link
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- Citations: 21
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Journal articleDong X, Yetisen AK, Köhler MH, et al., 2019,
Microscale Spectroscopic Mapping of 2D Optical Materials
, Advanced Optical Materials, Pages: 1900324-1900324, ISSN: 2195-1071 -
Journal articleMoreddu R, Elsherif M, Butt H, et al., 2019,
Contact lenses for continuous corneal temperature monitoring
, RSC Advances, Vol: 9, Pages: 11433-11442, ISSN: 2046-2069Temperature variation is a ubiquitous medical sign to monitor ocular conditions including dry eye disease (DED), glaucoma, carotid artery stenosis, diabetic retinopathy, and vascular neuritis. The ability to measure OST in real time is desirable in point-of-care diagnostics. Here, we developed minimally invasive contact lens temperature sensors for continuous monitoring of the corneal temperature. The contact lens sensor consisted of a laser patterned commercial contact lens embedding temperature-sensitive Cholesteric Liquid Crystals (CLCs), which exhibited a fully reversible temperature-dependent color change in the visible spectrum. The contact lens allowed the corneal temperature to be mapped in four key areas, at distances of 0.0, 1.0, 3.0, and 5.0 mm from the pupil's edge. Liquid crystals exhibited a wavelength shift from 738 ± 4 nm to 474 ± 4 nm upon increasing the temperature from 29.0 °C to 40.0 °C, with a time responsivity of 490 ms and a negligible hysteresis. Readouts were performed using a smartphone, which output RGB triplets associated to temperature values. Contact lens sensors based on CLCs were fitted and tested on an ex vivo porcine eye and readouts were compared with infrared thermal measurements, resulting in an average difference of 0.3 °C.
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Journal articleYetisen AK, Soylemezoglu B, Dong J, et al., 2019,
Capillary flow in microchannel circuitry of scleral lenses
, RSC ADVANCES, Vol: 9, Pages: 11186-11193, ISSN: 2046-2069 -
Journal articleAlqurashi T, Alnufaili M, Hassan MU, et al., 2019,
Laser Inscription of Microfluidic Devices for Biological Assays
, ACS APPLIED MATERIALS & INTERFACES, Vol: 11, Pages: 12253-12260, ISSN: 1944-8244 -
Journal articleYin Y, Xiao G, Zhang K, et al., 2019,
Tacrolimus- and Nerve Growth Factor-Treated Allografts for Neural Tissue Regeneration
, ACS CHEMICAL NEUROSCIENCE, Vol: 10, Pages: 1411-1419, ISSN: 1948-7193 -
Journal articleCoskun AF, Topkaya SN, Yetisen AK, et al., 2019,
Portable multiplex optical assays
, Advanced Optical Materials, Vol: 7, Pages: 1-25, ISSN: 2195-1071Global health issues are increasingly becoming critical with high fatality rate due to chronic and infectious diseases. Emerging technologies aim to address these problems by understanding the causes of lethal conditions and diagnosing symptoms at early stage. Existing commercial diagnostics primarily focus on single-plex assays due to ease-of-use, simplicity in analysis, and amenability to mass manufacturing. Many research grade devices have utilized only a few molecular and morphological signatures in bodily fluids. However, multiplex devices can improve accuracy, sensitivity, and scalability of research and diagnostic devices. This review presents multiplex assays that utilize optical, electrical, and chemical methods and materials that have the potential to improve portable point-of-care diagnostics. The critical role of emerging optical and complementary assays with multiple contrast mechanisms is investigated to enable highly multiplex analysis in field settings. Multiparameter portable devices for field applications toward health monitoring, food testing, air quality monitoring, and microanalysis in other extreme conditions are examined. Current trends indicate the need for validation of health diagnosis based on a large number of biomarkers in randomized clinical trials. Advanced digital analysis, crowd-sourced solutions, and robust user interfaces will become an integral part of the connected global health systems and personalized monitoring platforms.
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Journal articleDong J, Wang S, Lu M, et al., 2019,
Real-time dual-sensitive shearography for simultaneous in-plane and out-of-plane strain measurements
, Optics Express, Vol: 27, Pages: 3276-3283, ISSN: 1094-4087A real-time, dual-sensitive shearography system using a single-wavelength laser was developed for simultaneous and dynamic in-plane and out-of-plane strain measurements. The shearography system is capable of measuring crack-tip deformation fields quantitatively. A spatial multiplexing technique based on Fourier transform is employed for simultaneous and dynamic multi-component phase retrieval. Two slit spatial filters and a common-path shearing interferometer are used to obtain an improved phase quality for crack-tip deformation measurements. Mode-I fracture experiments under three-point bending were conducted to validate the feasibility and the capability of this method.
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Journal articleYetisen AK, Martinez-Hurtado JL, Uenal B, et al., 2018,
Wearables in medicine
, Advanced Materials, Vol: 30, Pages: 1-26, ISSN: 0935-9648Wearables as medical technologies are becoming an integral part of personal analytics, measuring physical status, recording physiological parameters, or informing schedule for medication. These continuously evolving technology platforms do not only promise to help people pursue a healthier life style, but also provide continuous medical data for actively tracking metabolic status, diagnosis, and treatment. Advances in the miniaturization of flexible electronics, electrochemical biosensors, microfluidics, and artificial intelligence algorithms have led to wearable devices that can generate real-time medical data within the Internet of things. These flexible devices can be configured to make conformal contact with epidermal, ocular, intracochlear, and dental interfaces to collect biochemical or electrophysiological signals. This article discusses consumer trends in wearable electronics, commercial and emerging devices, and fabrication methods. It also reviews real-time monitoring of vital signs using biosensors, stimuli-responsive materials for drug delivery, and closed-loop theranostic systems. It covers future challenges in augmented, virtual, and mixed reality, communication modes, energy management, displays, conformity, and data safety. The development of patient-oriented wearable technologies and their incorporation in randomized clinical trials will facilitate the design of safe and effective approaches.
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Journal articleYetisen AK, 2018,
Biohacking
, TRENDS IN BIOTECHNOLOGY, Vol: 36, Pages: 744-747, ISSN: 0167-7799- Author Web Link
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- Citations: 26
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Journal articleAlQattan B, Yetisen AK, Butt H, 2018,
Direct laser writing of nanophotonic structures on contact lenses
, ACS Nano, Vol: 12, Pages: 5130-5140, ISSN: 1936-0851Contact lenses are ubiquitous biomedical devices used for vision correction and cosmetic purposes. Their application as quantitative analytical devices is highly promising for point-of-care diagnostics. However, it is a challenge to integrate nanoscale features into commercial contact lenses for application in low-cost biosensors. A neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (1064 nm, 3 ns pulse, 240 mJ) in holographic interference patterning mode was utilized to produce optical nanostructures over the surface of a hydrogel contact lens. One-dimensional (925 nm) and two-dimensional (925 nm × 925 nm) nanostructures were produced on contact lenses and analyzed by spectroscopy and angle-resolve measurements. The holographic properties of these nanostructures were tested in ambient moisture, fully hydrated, and artificial tear conditions. The measurements showed a rapid tuning of optical diffraction from these nanostructures from 41 to 48°. The nanostructures were patterned near the edges of the contact lens to avoid any interference and obstruction to the human vision. The formation of 2D nanostructures on lenses increased the diffraction efficiency by more than 10%. The versatility of the holographic laser ablation method was demonstrated by producing four different 2D nanopattern geometries on contact lenses. Hydrophobicity of the contact lens was characterized by contact angle measurements, which increased from 59.0° at pristine condition to 62.5° at post-nanofabrication. The holographic nanostructures on the contact lens were used to sense the concentration of Na+ ions. Artificial tear solution was used to simulate the conditions in dry eye syndrome, and nanostructures on the contact lenses were used to detect the electrolyte concentration changes (±47 mmol L–1). Nanopatterns on a contact lens may be used to sense other ocular diseases in early stages at point-of-care settings.
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Journal articleElsherif M, Hassan MU, Yetisen AK, et al., 2018,
Wearable contact lens biosensors for continuous glucose monitoring using smartphones
, ACS Nano, Vol: 12, Pages: 5452-5462, ISSN: 1936-0851Low-cost, robust, and reusable continuous glucose monitoring systems that can provide quantitative measurements at point-of-care settings is an unmet medical need. Optical glucose sensors require complex and time-consuming fabrication processes, and their readouts are not practical for quantitative analyses. Here, a wearable contact lens optical sensor was created for the continuous quantification of glucose at physiological conditions, simplifying the fabrication process and facilitating smartphone readouts. A photonic microstructure having a periodicity of 1.6 μm was printed on a glucose-selective hydrogel film functionalized with phenylboronic acid. Upon binding with glucose, the microstructure volume swelled, which modulated the periodicity constant. The resulting change in the Bragg diffraction modulated the space between zero- and first-order spots. A correlation was established between the periodicity constant and glucose concentration within 0–50 mM. The sensitivity of the sensor was 12 nm mM–1, and the saturation response time was less than 30 min. The sensor was integrated with commercial contact lenses and utilized for continuous glucose monitoring using smartphone camera readouts. The reflected power of the first-order diffraction was measured via a smartphone application and correlated to the glucose concentrations. A short response time of 3 s and a saturation time of 4 min was achieved in the continuous monitoring mode. Glucose-sensitive photonic microstructures may have applications in point-of-care continuous monitoring devices and diagnostics at home settings.
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Journal articleBadawy A-R, Hassan MU, Elsherif M, et al., 2018,
Contact lenses for color blindness
, Advanced Healthcare Materials, Vol: 7, Pages: 1-7, ISSN: 2192-2640Color vision deficiency (color blindness) is an inherited genetic ocular disorder. While no cure for this disorder currently exists, several methods can be used to increase the color perception of those affected. One such method is the use of color filtering glasses which are based on Bragg filters. While these glasses are effective, they are high cost, bulky, and incompatible with other vision correction eyeglasses. In this work, a rhodamine derivative is incorporated in commercial contact lenses to filter out the specific wavelength bands (≈545–575 nm) to correct color vision blindness. The biocompatibility assessment of the dyed contact lenses in human corneal fibroblasts and human corneal epithelial cells shows no toxicity and cell viability remains at 99% after 72 h. This study demonstrates the potential of the dyed contact lenses in wavelength filtering and color vision deficiency management.
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Journal articleJiang N, Butt H, Montelongo Y, et al., 2018,
Laser Interference Lithography for the Nanofabrication of Stimuli-Responsive Bragg Stacks
, ADVANCED FUNCTIONAL MATERIALS, Vol: 28, ISSN: 1616-301X -
Journal articleJiang N, Ying G-L, Yetisen AK, et al., 2018,
A bilayered nanoshell for durable protection of single yeast cells against multiple, simultaneous hostile stimuli
, CHEMICAL SCIENCE, Vol: 9, ISSN: 2041-6520- Author Web Link
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- Citations: 20
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Journal articleYi J, Jiang N, Li B, et al., 2018,
Painful Terminal Neuroma Prevention by Capping PRGD/PDLLA Conduit in Rat Sciatic Nerves
, ADVANCED SCIENCE, Vol: 5, ISSN: 2198-3844 -
Journal articleAlqurashi Y, Bajgrowicz-Cieslak M, Hassan MU, et al., 2018,
Laser-Induced Surface Modification of Contact Lenses
, ADVANCED ENGINEERING MATERIALS, Vol: 20, ISSN: 1438-1656 -
Journal articleRashid I, Hassan MU, Khandwalla A, et al., 2018,
Structural Coloration in Caloenas Nicobarica Pigeons and Refractive Index Modulated Sensing
, ADVANCED OPTICAL MATERIALS, Vol: 6, ISSN: 2195-1071 -
Journal articleLiu Q, Jiang N, Liu D, et al., 2018,
Monodispersed silk fibroin microdroplets for protein stabilization
, Applied Physics Letters, Vol: 112, Pages: 1-4, ISSN: 0003-6951Low stability of globular protein droplets in emulsion significantly limits their applications in drug encapsulation, long-term storage, and controlled drug release. Here, a microfluidic flow-focusing device was utilized to synthesize horseradish peroxidase (HRP)-loaded silk fibroin microdroplets. The two immiscible streams of microfluidic flow-focusing were regenerated by silk fibroin solution and a mixture of 95 wt. % sunflower oil and 5 wt. % span 80 as the dispersed and continuous phases, respectively. In this study, the water-in-oil silk fibroin microdroplets were homogeneously produced by leveraging the discrete and periodic breakup of microdroplets and regulating the flow rates. Moreover, the result showed that the stability of encapsulated HRP in microdroplets was 25% higher than that of HRP after 6 weeks incubation. Thus, the microfluidic flow-focusing is a promising technique to form monodisperse microdroplets and maximize the stability of protein droplets.
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Journal articleAlqurashi T, Alhosani A, Dauleh M, et al., 2018,
Laser inscription of pseudorandom structures for microphotonic diffuser applications
, Nanoscale, Vol: 10, Pages: 7095-7107, ISSN: 2040-3364Optical diffusers provide a solution for a variety of applications requiring a Gaussian intensity distribution including imaging systems, biomedical optics, and aerospace. Advances in laser ablation processes have allowed the rapid production of efficient optical diffusers. Here, we demonstrate a novel technique to fabricate high-quality glass optical diffusers with cost-efficiency using a continuous CO2 laser. Surface relief pseudorandom microstructures were patterned on both sides of the glass substrates. A numerical simulation of the temperature distribution showed that the CO2 laser drills a 137 μm hole in the glass for every 2 ms of processing time. FFT simulation was utilized to design predictable optical diffusers. The pseudorandom microstructures were characterized by optical microscopy, Raman spectroscopy, and angle-resolved spectroscopy to assess their chemical properties, optical scattering, transmittance, and polarization response. Increasing laser exposure and the number of diffusing surfaces enhanced the diffusion and homogenized the incident light. The recorded speckle pattern showed high contrast with sharp bright spot free diffusion in the far field view range (250 mm). A model of glass surface peeling was also developed to prevent its occurrence during the fabrication process. The demonstrated method provides an economical approach in fabricating optical glass diffusers in a controlled and predictable manner. The produced optical diffusers have application in fibre optics, LED systems, and spotlights.
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Journal articleKhalid MW, Ahmed R, Yetisen AK, et al., 2018,
Holographic writing of ink-based phase conjugate nanostructures via laser ablation (vol 7, 10603, 2017)
, Scientific Reports, Vol: 8, Pages: 1-1, ISSN: 2045-2322 -
Journal articleJiang N, Montelongo Y, Butt H, et al., 2018,
Microfluidic contact lenses
, Small, Vol: 14, Pages: 1-9, ISSN: 1613-6810Contact lens is a ubiquitous technology used for vision correction and cosmetics. Sensing in contact lenses has emerged as a potential platform for minimally invasive point-of-care diagnostics. Here, a microlithography method is developed to fabricate microconcavities and microchannels in a hydrogel-based contact lens via a combination of laser patterning and embedded templating. Optical microlithography parameters influencing the formation of microconcavities including ablation power (4.3 W) and beam speed (50 mm s−1) are optimized to control the microconcavity depth (100 µm) and diameter (1.5 mm). The fiber templating method allows the production of microchannels having a diameter range of 100–150 µm. Leak-proof microchannel and microconcavity connections in contact lenses are validated through flow testing of artificial tear containing fluorescent microbeads (Ø = 1–2 µm). The microconcavities of contact lenses are functionalized with multiplexed fluorophores (2 µL) to demonstrate optical excitation and emission capability within the visible spectrum. The fabricated microfluidic contact lenses may have applications in ophthalmic monitoring of metabolic disorders at point-of-care settings and controlled drug release for therapeutics.
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