Cooperstein I, Indukuri SRKC, Bouketov A, Levy U, Magdassi S. 3D Printing of Micrometer-Sized Transparent Ceramics with On-Demand Optical-Gain Properties. Advanced Materials [Internet]. 2020 :2001675 - 2001675. Publisher's VersionAbstract
Transparent ceramics are usually polycrystalline materials, which are wildly used in many optical applications, such as lasers. As of today, the fabrication of transparent ceramic structures is still limited to conventional fabrication methods, which do not enable the formation of complex structures. A new approach for 3D printing of micrometer-size, transparent ceramic structures is presented. By using a solution of metal salts that can undergo a sol–gel process and photopolymerization by two-photon printing, micrometer-sized yttrium aluminum garnet (YAG) structures doped with neodymium (Nd) are fabricated. The resulting structures are not only transparent in the visible spectrum but can also emit light at 1064 nm due to the doping with Nd. By using solution-based precursors, without any particles, the sintering can be performed under air at ambient pressure and at a relatively low temperature, compared to conventional processes for YAG. The crystalline structure is imaged at atomic resolution by ultrahigh-resolution scanning transmission electron microscopy (STEM), indicating that the doped Nd atoms are located at the yttrium positions. Such miniaturized structures can be used for diverse applications, e.g., optical components in high-intensity laser systems, which require heat resistance, or as light sources in optical circuits.
Zhou X, Parida K, Halevi O, Liu Y, Xiong J, Magdassi S, Lee PS. All 3D-printed stretchable piezoelectric nanogenerator with non-protruding kirigami structure. Nano Energy [Internet]. 2020;72 :104676 - 104676. Publisher's Version
Nguyen TD, Yeo LP, Si Yang K, Kei TC, Wang Z, Mandler D, Magdassi S, Tok AIY. Fabrication and characterization of graphene quantum dots thin film for reducing cross-sectional heat transfer through smart window. Materials Research Bulletin [Internet]. 2020;127 :110861 - 110861. Publisher's VersionAbstract
Graphene and its derivatives have been reported as materials with excellent electrical and thermal conductivity, allowing for various promising applications. In particular, the large-scale surface coating of graphene-based materials can be employed to minimize cross-sectional heat transfer through the glass window. This study introduces a facile and cost-effective method to fabricate graphene quantum dots (GQDs) thin film on Fluorine-doped Tin Oxide (FTO) glass via casting of the GQDs dispersion and stabilizing with poly-vinyl-pyrrolidone (PVP). The thin film possesses excellent optical properties of GQDs and allows more than 80% of visible transmittance. The presence of the GQDs thin film shows effective reduction in the cross-sectional thermal diffusivity of FTO glass, from 0.55 mm2/s to zero when measured with laser flash over a 4-second period. This low cost and eco-friendly GQDs thin film will be a promising material for heat management in smart window applications.
Keneth ES, Lieberman R, Rednor M, Scalet G, Auricchio F, Magdassi S. Multi-Material 3D Printed Shape Memory Polymer with Tunable Melting and Glass Transition Temperature Activated by Heat or Light. Polymers [Internet]. 2020;12 (3) :710 - 710. Publisher's VersionAbstract
Shape memory polymers are attractive smart materials that have many practical applications and academic interest. Three-dimensional (3D) printable shape memory polymers are of great importance for the fabrication of soft robotic devices due to their ability to build complex 3D structures with desired shapes. We present a 3D printable shape memory polymer, with controlled melting and transition temperature, composed of methacrylated polycaprolactone monomers and N-Vinylcaprolactam reactive diluent. Tuning the ratio between the monomers and the diluents resulted in changes in melting and transition temperatures by 20, and 6 °C, respectively. The effect of the diluent addition on the shape memory behavior and mechanical properties was studied, showing above 85% recovery ratio, and above 90% fixity, when the concentration of the diluent was up to 40 wt %. Finally, we demonstrated multi-material printing of a 3D structure that can be activated locally, at two different temperatures, by two different stimuli; direct heating and light irradiation. The remote light activation was enabled by utilizing a coating of Carbon Nano Tubes (CNTs) as an absorbing material, onto sections of the printed objects.
Halevi O, Chen TY, Lee PS, Magdassi S, Hriljac JA. Nuclear wastewater decontamination by 3D-Printed hierarchical zeolite monoliths. RSC Advances. 2020;10 (10) :5766 - 5776.Abstract
The selective removal of radioactive cationic species, specifically 137Cs+ and 90Sr2+, from contaminated water is critical for nuclear waste remediation processes and environmental cleanup after accidents, such as the Fukushima Daiichi Nuclear Power Plant disaster in 2011. Nanoporous silicates, such as zeolites, are most commonly used for this process but in addition to acting as selective ion exchange media must also be deployable in a correct physical form for flow columns. Herein, Digital Light Processing (DLP) three-dimensional (3D) printing was utilized to form monoliths from zeolite ion exchange powders that are known to be good for nuclear wastewater treatment. The monoliths comprise 3D porous structures that will selectively remove radionuclides in an engineered form that can be tailored to various sizes and shapes as required for any column system and can even be made with fine-grained powders unsuitable for normal gravity flow column use. 3D-printed monoliths of zeolites chabazite and 4A were made, characterized, and evaluated for their ion exchange capacities for cesium and strontium under static conditions. The 3D-printed monoliths with 50 wt% zeolite loadings exhibit Cs and Sr uptake with an equivalent ion-capacity as their pristine powders. These monoliths retain their porosity, shape and mechanical integrity in aqueous media, providing a great potential for use to not only remove radionuclides from nuclear wastewater, but more widely in other aqueous separation-based applications and processes.
Sousa V, Gonçalves BF, Rosen YS, Virtuoso J, Anacleto P, Cerqueira MF, Modin E, Alpuim P, Lebedev OI, Magdassi S, et al. Over 6% Efficient Cu(In,Ga)Se2 Solar Cell Screen-Printed from Oxides on FTO. ACS Applied Energy Materials [Internet]. 2020 :acsaem.9b01999 - acsaem.9b01999. Publisher's VersionAbstract
A new approach to fabricate Cu(In,Ga)Se2 solar cells on conductive fluorine-doped tin oxide (FTO) is reported, in which commercial CuO, In2O3, and Ga2O3 are formulated into high-quality ink based o...
Tibi G, Keneth ES, Layani M, Magdassi S, Degani A. Three-Layered Design of Electrothermal Actuators for Minimal Voltage Operation. Soft Robotics [Internet]. 2020 :soro.2018.0160 - soro.2018.0160. Publisher's VersionAbstract
By designing an actuator composed of thin layers with different coefficients of thermal expansion (CTE) together with an electrically conductive layer, the CTE mismatch can be utilized to produce s...
lioz etgar, Magdassi S, Aharon S, Layani M.; 2019. Self-assembly of perovskite for fabrication of transparent devices. United States of America patent US US20190070111A1.Abstract

The present invention relates to the use of pomegranate oil and fractions thereof for preventing and treating neurodegenerative diseases. Particularly, the present invention relates to emulsions of the pomegranate oil or fractions thereof for the prevention and treatment of brain diseases, including Creutzfeldt-Jacob disease (CJD) and multiple sclerosis (MS).

Keneth ES, Epstein AR, Harari MS, Pierre RS, Magdassi S, Bergbreiter S. 3D Printed Ferrofluid Based Soft Actuators, in Institute of Electrical and Electronics Engineers (IEEE) ; 2019 :7569 - 7574.Abstract
This work demonstrates 3D printed soft actuators with complex shapes and remote actuation using an external magnetic field. Instead of embedding magnetic particles in a polymeric matrix, we fabricated a novel ferrofluid-based actuator, in which the fluid can be moved to different locations in the actuator to affect actuator response. We studied the effect of both the ferrofluid and the 3D printed material on the motion of simple actuators using 3D printed tubes. In addition, we 3D printed more complex actuators mimicking a human hand and a worm to demonstrate more complex motion.
Kam D, Layani M, BarkaiMinerbi S, Orbaum D, Abrahami BenHarush S, Shoseyov O, Magdassi S. Additive Manufacturing of 3D Structures Composed of Wood Materials. Advanced Materials Technologies. 2019.
Tok A, Nguyen TD, Geuli O, Yeo LP, Mandler D, Magdassi S. Additive‐free electrophoretic deposition of graphene quantum dots thin films. Chemistry – A European Journal [Internet]. 2019 :chem.201903596 - chem.201903596. Publisher's Version
Kam D, Chasnitsky M, Nowogrodski C, Braslavsky I, Abitbol T, Magdassi S, Shoseyov O. Direct Cryo Writing of Aerogels Via 3D Printing of Aligned Cellulose Nanocrystals Inspired by the Plant Cell Wall. Colloids and Interfaces. 2019;3 (2) :46 - 46.Abstract
Aerogel objects inspired by plant cell wall components and structures were fabricated using extrusion-based 3D printing at cryogenic temperatures. The printing process combines 3D printing with the alignment of rod-shaped nanoparticles through the freeze-casting of aqueous inks. We have named this method direct cryo writing (DCW) as it encompasses in a single processing step traditional directional freeze casting and the spatial fidelity of 3D printing. DCW is demonstrated with inks that are composed of an aqueous mixture of cellulose nanocrystals (CNCs) and xyloglucan (XG), which are the major building blocks of plant cell walls. Rapid fixation of the inks is achieved through tailored rheological properties and controlled directional freezing. Morphological evaluation revealed the role of ice crystal growth in the alignment of CNCs and XG. The structure of the aerogels changed from organized and tubular to disordered and flakey pores with an increase in XG content. The internal structure of the printed objects mimics the structure of various wood species and can therefore be used to create wood-like structures via additive manufacturing technologies using only renewable wood-based materials.
Yeo LP, Nguyen TD, Ling H, Lee Y, Mandler D, Magdassi S, Tok AIY. Electrophoretic deposition of reduced graphene oxide thin films for reduction of cross-sectional heat diffusion in glass windows. Journal of Science: Advanced Materials and Devices. 2019;4 (2) :252 - 259.Abstract
Effective management of heat transfer, such as conduction and radiation, through glass windows is one of the most challenging issues in smart window technology. In this work, reduced Graphene Oxide (rGO) thin films of varying thicknesses are fabricated onto Fluorine-doped Tin Oxide (FTO) glass via electrophoretic deposition technique. The sample thicknesses increase with increasing number of deposition cycles (5, 10, 20 cycles). It is hypothesized that such rGO thin films, which are well-known for their high thermal conductivities, can conduct heat away laterally towards heat sinks and reduce near-infrared (NIR) transmittance through them, thus effectively slowing down the temperature increment indoors. The performance of rGO/FTO in reducing indoor temperatures is investigated with a solar simulator and a UV-Vis-NIR spectrophotometer. The 20-cycles rGO thin films showed 30% more NIR blocked at 1000 nm as compared to clean FTO, as well as the least temperature increment of 0.57 °C following 30 min of solar irradiation. Furthermore, the visible transmittance of the as-fabricated rGO films remain on par with commercial solar films, enabling up to 60% of visible light transmittance for optimal balance of transparency and heat reduction. These results suggest that the rGO thin films have great potential in blocking heat transfer and are highly recommended for smart window applications.
Rosental T, Magdassi S. A New Approach to 3D Printing Dense Ceramics by Ceramic Precursor Binders. Advanced Engineering Materials. 2019 :1900604 - 1900604.Abstract
© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Fabrication of dense ceramic objects by 3D printing processes is important in achieving improved functions in many applications, such as mechanical, optical, and electrical devices. It is a challenging process, mainly due to the high content of organic binders within the printed object. Upon heating and sintering, the printed object shrinks and becomes porous due to the decomposition of the organic binder. Herein, a new approach is presented based on the utilization of an inorganic binder that is a sol–gel precursor for the same material composing the dispersed ceramic particles. The approach is demonstrated in printing objects composed of barium titanate (BTO), which is an important dielectric and piezoelectric material. This binder also enables us to achieve dispersions with high solid load that exhibits a shear-thinning rheological behavior, which is essential for direct ink writing (DIW) printing technology. The as-printed parts contain only 1 wt% organic materials, having 97.8% of the theoretical density, whereas the BTO binder crystalizes upon heating, without forming undesired secondary phases.
Raz LS, Keneth ES, Jang Y, Shapiro A, Cohen E, Yochelis S, Lifshitz E, Magdassi S, Paltiel Y. Simple fabrication of SWIR detectors based on wet deposition of carbon nanotubes and quantum dots. Sensors and Actuators, A: Physical. 2019;295 :469 - 473.Abstract
Over the last two decades, carbon based materials and especially carbon nanotubes (CNTs), were the subject of many studies, mainly due to their unique electrical, optical and mechanical properties (Ouyang et al., 2002; Dresselhaus et al., 2003; Dresselhaus et al., 1995). CNTs can combine electrical conductivity with wide absorption spectra, and can be produced in large scale (Danafar et al., 2009) [4]. These properties enable to realize CNTs in simple, low-cost detector. Here we present a proof-of-concept for such a detector operating at the short-wave infrared (SWIR) regime. We use a simple spray technique, which allows creating a large matrix of CNT bundles. Semiconducting quantum dots (QDs) were adsorbed on top of the CNTs, enhancing the sensitivity to the infrared regime. This regime is important for numerous applications in the civil, medical, defense and security fields. Controlled coupling between the QDs and the CNT matrix generates gate-like electro-optical response when light is absorbed. This proof-of-concept for a detector in the SWIR region is presented for large surfaces and substrates, while the responsivity and detectivity of the detector in a range of frequencies and wavelengths was evaluated.
Cai P, Li Z, Keneth ES, Wang L, Wan C, Jiang Y, Hu B, Wu Y-L, Wang S, Lim CT, et al. Differential Homeostasis of Sessile and Pendant Epithelium Reconstituted in a 3D-Printed "GeminiChip". Advanced materials (Deerfield Beach, Fla.). 2019 :e1900514.Abstract

Local mechanical cues can affect crucial fate decisions of living cells. Transepithelial stress has been discussed in the context of epithelial monolayers, but the lack of appropriate experimental systems leads current studies to approximate it simply as an in-plane stress. To evaluate possible contribution of force vectors acting in other directions, double epithelium in a 3D-printed "GeminiChip" containing a sessile and a pendant channel is reconstituted. Intriguingly, the sessile epithelia is prone to apoptotic cell extrusion upon crowding, whereas the pendant counterpart favors live cell delamination. Transcriptome analyses show upregulation of RhoA, BMP2, and hypoxia-signaling genes in the pendant epithelium, consistent with the onset of an epithelial-mesenchymal transition program. HepG2 microtumor spheroids also display differential spreading patterns in the sessile and pendant configuration. Using this multilayered GeminiChip, these results uncover a progressive yet critical role of perpendicular force vectors in collective cell behaviors and point at fundamental importance of these forces in the biology of cancer.

Maldonado N, Vegas VG, Halevi O, Martinez JI, Lee PS, Magdassi S, Wharmby MT, Platero-Prats AE, Moreno C, Zamora F, et al. 3D Printing of a Thermo- and Solvatochromic Composite Material Based on a Cu(II)-Thymine Coordination Polymer with Moisture Sensing Capabilities. Advanced Functional Materials. 2019;29 (15) :n/a.Abstract

This work presents the fabrication of 3D-printed composite objects based on copper(II) 1D coordination polymer (CP1) decorated with thymine along its chains with potential utility as an environmental humidity sensor and as a water sensor in organic solvents. This new composite object has a remarkable sensitivity, ranging from 0.3% to 4% of water in organic solvents. The sensing capacity is related to the structural transformation due to the loss of water mols. that CP1 undergoes with temperature or by solvent mols.′ competition, which induces significant change in color simultaneously. The CP1 and 3D printed materials are stable in air over 1 yr and also at biol. pHs (5-7), therefore suggesting potential applications as robust colorimetric sensors. These results open the door to generate a family of new 3D printed materials based on the integration of multifunctional coordination polymers with organic polymers.

Verbitsky L, Waiskopf N, Magdassi S, Banin U. A clear solution: semiconductor nanocrystals as photoinitiators in solvent free polymerization. Nanoscale. 2019;11 (23) :11209 - 11216.Abstract

Semiconductor nanocrystals have been shown to have unique advantages over traditional organic photoinitiators for polymerization in solution However, efficient photoinitiation with such nanoparticles in solvent-free and additive-free formulations so far has not been achieved. Herein, the ability to use semiconductor nanocrystals for efficient bulk polymerization as sole initiators is reported, operating under modern UV-blue-LED light sources found in 3D printers and other photocuring applications. Hybrid semiconductor-metal nanorods exhibit superior photoinitiation capability to their pristine semiconductor counterparts, attributed to the enhanced charge separation and oxygen consumption in such systems. Moreover, photoinitiation by semiconductor nanocrystals overcoated by inorganic ligands is reported, thus increasing the scope of possible applications and shedding light on the photoinitiation mechanism; in light of the results, two possible pathways are discussed - ligand-mediated and cation-coordinated oxidation A demonstration of the unique attributes of the quantum photoinitiators is reported in their use for high-resolution two-photon printing of optically fluorescing microstructures, demonstrating a multi-functionality capability. The bulk polymerization demonstrated here can be advantageous over solvent based methods as it alleviates the need of post-polymerization drying and reduces waste and exposure to toxic solvents, as well as broadens the possible use of quantum photoinitiators for industrial and research uses.

Kamyshny A, Magdassi S. Conductive nanomaterials for 2D and 3D printed flexible electronics. Chemical Society Reviews. 2019;48 (6) :1712 - 1740.Abstract

This review describes recent developments in the field of conductive nanomaterials and their application in 2D and 3D printed flexible electronics, with particular emphasis on inks based on metal nanoparticles and nanowires, carbon nanotubes, and graphene sheets. We present the basic properties of these nanomaterials, their stabilization in dispersions, formulation of conductive inks and formation of conductive patterns on flexible substrates (polymers, paper, textile) by using various printing technologies and post-printing processes. Applications of conductive nanomaterials for fabrication of various 2D and 3D electronic devices are also briefly discussed.

Nguyen TD, Yeo LP, Kei TC, Mandler D, Magdassi S, Tok AIY. Efficient Near Infrared Modulation with High Visible Transparency Using SnO2-WO3 Nanostructure for Advanced Smart Windows. Advanced Optical Materials. 2019;7 (8) :n/a.Abstract

Renewable energy technol. and effective energy management are the most crucial factors to consider in the progress toward worldwide energy sustainability. Smart window technol. has a huge potential in energy management as it assists in reducing energy consumption of indoor lighting and air-conditioning in buildings. Electrochromic (EC) materials, which can elec. modulate the transmittance of solar radiation, are one of the most studied smart window materials. In this work, highly transparent SnO2 inverse opal (IO) is used as the framework to electrochem. deposit amorphous WO3 layer to fabricate hybrid SnO2-WO3 core-shell IO structure. The hybrid structure is capable of effective near IR (NIR) modulation while maintaining high visible light transparency in the colored and bleached states. By varying the initial diameter of the polystyrene (PS) opal template and the WO3 electrodeposition time, optimal results can be obtained with the smallest PS diameter of 392 nm and 180 s WO3 electrodeposition. In its colored state, the 392-SnO2-WO3-180 core-shell IO structure shows ≈70% visible light transparency, 62% NIR blockage at 1200 nm, and ≈15% drop in NIR blocking stability after 300 cycles. The SnO2-WO3 core-shell IO structure in this study is a promising EC material for advanced smart window technol.