Research

The research group headed by Prof. S. Magdassi focuses on materials science and nanotechnology. The main research fields of the group are formation and stabilization of inorganic and organic and nanomaterials, formulation of these materials in various inks and delivery systems, and their application in a variety of fields such as 3D and functional printing, solar energy and bio-medical systems. Current research projects include: conductive inks for printed electronics, transparent conductive electrodes, materials for 3D printing, inkjet inks formulations, coatings and inks for solar energy applications, nanoparticles for bio-imaging, drug delivery and cosmetic formulations. For more details on our research fields, see links on the left.

Based on some of the research projects, commercial activities evolved leading to worldwide sales and establishing new companies.

Current research projects include:

Functional printing and coatings
Silver nanoparticles inks
Copper inks : nano particles and precursor inks
CNT inks
3D polymeric inks
3D ceramic inks
Printed actuators
Thermosolar coatings
Transparent electrodes
Digital glass printing
UV ink formulations
Inks for printed electronics

Delivery systems
Organic nanoparticles
Nanoemulsions
Nanomaterials for medical imaging
Nanomaterials for cosmetics
Diagnostic devices

3-D and 4-D Printing

The field of additive manufacturing (more commonly known as three-dimensional printing) has developed significantly in recent years, consequently increasing the need for new materials for the fabrication of functional 3D structures. It is currently being used for a variety of applications ranging from modelling to medical devices. Current methods are based on layer-by-layer fabrication of a three dimensional structure, each layer being built by one of the following methods: (1) Fuse Deposition Modelling (FDM) based on melting a material which is typically a polymer (2) Selective Laser Sintering (SLS) based on laser melting of powder particles, (3), Color Jet Printing (CJP) based on jetting a binder onto a powder, and (4),stereo lithography (SLA) which is based on selective curing of polymerizable monomers. A common method for this technique is Digital Light Processing (DLP) which is based on selective polymerization of individual pixels within a thin layer. This is done by using a digital micro mirror device (DMD) that results in small dots (tens of micrometers).

Our research is focused on developing new materials for most types of 3D printing technologies, including conductive inks, ceramic materials and metals, and shape memory polymers. Some of the research activities will be described in the following sections.

 

Highly Stretchable and UV Curable Elastomer for Three Dimensional Printing

We have developed compositions of highly stretchable and UV curable (SUV) elastomers that can be stretched by up to 1100%, which is more than five times the elongation at break of the existing UV curable elastomers and are suitable for UV curing based 3D printing technologies. Using DLP printing with the SUV elastomer compositions enabled the direct creation of complex 3D lattices or hollow structures that exhibit extremely large deformation. For example, we directly printed a soft actuator and a soft robotic gripper which have a complex 3D and hollow structures and can undergo large local deformations (Fig. 1). We also demonstrated a 3D Bucky ball light switch by combining the DLP printing with a silver nanoparticles coating and room temperature sintering process. Overall, the SUV elastomers will significantly enhance the capability of the DLP based 3D printing of fabricating soft and deformable 3D structures and devices including soft actuators and robots, flexible electronics, acoustic metamaterials, and many other applications (The scale bar in the figures in 10 mm). Adv. Mater. DOI: 10.1002/adma.201606000.

Shows different 3D printed structures such as soft actuator, gripper, spherical balloon and electronic switches using SUV elasto

Figure 1. Shows different 3D printed structures such as soft actuator, gripper, spherical balloon and electronic switches using SUV elastomer

 

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Porous structures by printing Oil-in-Water emulsions

A new ink  was developed for printing porous structures that can be used for embedding various functional materials. The ink is composed of a UV polymerizable Oil-in-Water emulsion which can be converted into a solid object upon UV irradiation, forming a porous structure after evaporation of the water phase. The water phase can contain silver NP that are sintered by a chemical sintering, resulting in a 3D conductive structure (Fig.2). The surface area of the object can be controlled by changing the emulsion's droplets size and the dispersed phase fraction. see: Journal of Materials Chemistry C 1.19 (2013): 3244-3249. and Journal of Materials Chemistry C 3.9 (2015): 2040-2044. 

Fig. 1: Printed 3D porous (left) and conductive objects (right)

 Fig. 2: Printed 3D porous (left) and conductive objects (right)

3D and 4D printing of shape memory materials

Until now, Shape Memory Polymers  (SMPs) were not used in the field of 3D printing or flexible electronics due to inadequate processing technologies. We developed a new process and inks which enables printing of oligomer melts in a DLP printer, to generate high-resolution three-dimensional (3D) shape memory structures (Fig. 3). We also demonstrated how these printed structures can be further utilized for constructing flexible electronic devices (Fig.4), see:  Adv. Mater.. doi:10.1002/adma.201503132 

Fig. 2: 3D printed structures changing shape upon heating due to the shape memory polymer.

Fig. 3: 3D printed structures changing shape upon heating due to the shape memory polymer.

Fig. 3: Printed 3D electrical circuit made of shape memory polymers, activated by heat.

Fig. 4: Printed 3D electrical circuit made of shape memory polymers, activated by heat.

Colloid and Interface Science

Colloid and interface science is an interdisciplinary science combining chemistry and physics of heterogeneous systems consisting of aggregated amphiphilic molecules (micelles) dispersed in liquids, droplets of a liquid dispersed in another immiscible liquid (microemulsions, miniemulsions, and emulsions), and particles with a size range of 1 – 1000 nm, which are dispersed in a liquid. Since most colloidal systems are dynamically unstable, the addition of stabilizing agents (surfactants or polymers) acting by adsorbing at the surface of the dispersed particles and providing electrostatic, steric, or electrosteric, stabilization, is required

Colloid and interface science is widely applied in the chemical industry and in various fields such as pharmaceutics, nanotechnology, biotechnology, ceramics, paints and ink formulations. 

For a real life example on a colloidal system watch an read our movie: "Tahini Water-in-Oil Emulsion Turns Into Oil-in-Water Emulsion" followed by an explanation.

The research projects of our group are in general in two main fields: (i) nanoemulsion and  microemulsion formulations for applications such as drug delivery, imaging, cosmetics and agriculture and (ii) dispersions of nanoparticles for functional printing and coatings. Theses dispersions are applied as conductive inks for printed electronics (metallic nanoparticles and CNTs for fabrication of 2D and 3D electronic devices), solar absorbers in thermosolar and optical coatings, and organic materials as delivery systems. Several of the research activities will are described in the various sections of this website.

  1. S.Magdassi and A.Kamyshny (1996) Surface activity and functional properties of proteins. Surface Activity of Proteins: Chemical and Physicochemical Modifications (S.Magdassi, Ed.). Marcel Dekker, N.Y., pp. 1-38.
  2. S.Magdassi, A.Kamyshny, and A.Baszkin (2001) Interfacial properties of hydrophobically modified biomolecules: fundamental aspects and applications. J. Dispersion Sci. Technol. 22: 313-322.
  3. A.Kamyshny and S.Magdassi (2004) Microencapsulation. Encyclopedia of Surface and Colloid Science (P.Somasundaran, Ed.). Marcel Dekker, N.Y., pp. 1-15.
  4. K.Margulis-Goshen, A.Kamyshny, and S.Magdassi (2009) Application of surfactants in pharmaceutical dosage forms. Handbook of Detergents. Part E: Applications. (U.Zoller, Ed.). CRC Press, Boca Raton, pp. 455-468.
  5. G.Nizri, S.Lagerge, A.Kamyshny, and S.Magdassi (2008) Polymer-surfactant interactions: binding mechanism of sodium dodecyl sulfate to poly(diallyldimethylammonium chloride. J. Colloid Interface Sci. 320: 74-81.

Drug Delivery and Medical Imaging

This field of research is focused on preparation of nano and microemulsions, microencapsules, and organic nanoparticles, for application in various fields such as imaging and drug delivery.

Example for a delivery system developed in our lab for biomedical imaging is Near Infrared (NIR) fluorescent nanoparticles and liposomes for detection colorectal tumors and ureter visualization. The nanoparticles are prepared by using only non-covalent attachment processes of molecules which are approved for clinical use, see Journal of biomedical nanotechnology 10.6 (2014): 1041-1048. The formation process is schematically shown in Fig. 1.

 Fig. 1: schematic presentation of formation of NIR nanoparticles for tumor imaging

Fig. 1: schematic presentation of formation of NIR nanoparticles for tumor imaging

 Fig. 2: NIR detection of colorectal cancer

Fig. 2: NIR detection of colorectal cancer

 Another example is nanodroplets of pomegranate seed oil (PSO), for prevention and treatment of neurodegenerative diseases (in collaboration with Prof. R. Gabizon, Hadassha Hospital). PSO contains high concentrations of punicic acid, which is among the strongest natural antioxidants, and  it was found that PSO nanoemulsion significantly delayed disease presentation when administered to asymptomatic TgMHu2ME199K mice and postponed disease aggravation in already sick mice, see: Nanomedicine. (2014) Apr 2. pii: S1549-9634(14) 00133-6. The PSO nanoemulsions are further explored by Granalix.

Industrial Activities

ahava logo brightsource logo
slogel logo ripples logo
clearjet logo motherschoice logo
diptech logo nanodimension logo
HUJI printing center logo

Pictures of products related to research in our group:

 Solar tower (Bright Source

Yaniv working on a solar tower with a solar coating developed in Magdassi's group

Inkjet Printing

In the past decades, inkjet technology has changed the printing industry by providing a new digital and diverse method of printing. The printing process is based on jetting ink droplets through an orifice, and upon contact of the droplets on the substrate a pattern is formed. So far, inkjet technology has been most successfully implemented in graphic arts, including industrial, wide format printing on rigid and flexible substrates.  Recently, there has been an increasing interest in the emerging field  of inkjet printing functional materials. The versatility of the inkjet printing technology led to its application in a  wide range of fields,  such as electronics, displays, solar cells, sensors and even in printing organs.  

The inkjet process has many advantages. It is a non-contact process, which is a significant advantage compared to other printing processes. It can be applied to almost any substrate regardless of its composition, morphology, and other properties, by proper tailoring of the ink properties. The volume of the jetted droplets is very small, usually in the range of picoliters, and in general the printing process enables high precision and excellent reliability. In order to obtain successful printing, the inks must have chemical and physical properties which meet the  requirements for the specific inkjet printing technology. Therefore, the inks formulations are usually complex and contain a variety of materials (besides the functional material) such as wetting and rheological agents, polymeric binders, dispersants and adhesion promoters, depending on the nature of the particular application.

 A review on the general subject of inkjet inks is given in the book: "The chemistry of inkjet inks" edited by Prof. Magdassi.

 A major activity in the research group is developing inkjet inks with functional properties, such as conductive inks and transparent electrodes. The  inks contain a variety of materials as the functional components, such as metal nanoparticles and carbon nanotubes, dissolved or dispersed metal precursors, glass particles and nanoemulsions

Printed Electronics

The term printed electronics refers to the application of printing technologies for the fabrication of electronic circuits and devices, on rigid and  flexible and even stretchable substrates such as polymeric films and paper.

Traditionally, fabrication of electronic devices is based on well established processes such as photolithography, electroless deposition and vacuum deposition. These processes are usually complex, involve high cost equipment and require multi- steps such as photopolymerization and etching.

The market of printed electronics, which is estimated to exceed $300 billion over the next 20 years  Advanced materials 22.6 (2010): 673, requires manufacturing techniques that are faster, cheaper and eco-friendlier compared to traditional production methods, and that can be performed with flexible substrates too.

During recent years, there are many reports on using direct printing technologies for fabrication of electronic and optoelectronic devices, with the main advantage of depositing the required material only were needed (additive manufacturing processes). Printing technologies such as inkjet, transfer, gravure, screen and flexo enables rapid and low cost of printing of electrical circuits.

All these additive processes require inks which are tailored for the various printing method and the final application. The inks for printing electrical conductors are multi-component systems that contains a conducting material in a liquid vehicle (aqueous or organic) and various additives (such as rheology and surface tension modifiers, humectants, binders and defoamers) which enable optimal performance of the whole system, including the printing device and the substrate. The conductive material may be dispersed nanomaterial such as silver nanowires and copper nanoparticles, or a dissolved material such as organometallic compound and a conductive polymer. In our research group we focus on silver, copper and CNT inks. The silver inks were licensed to Nanodimensions,  through an agreement with Yissum, the tech transfer company of The Hebrew University.

Our publications on copper based inks for printed electronics:

1) Printing a Self-Reducing Copper Precursor on 2D and 3D Objects to Yield Copper Patterns with 50% Copper's Bulk Conductivity
2) Self-reduction of a copper complex MOD ink for inkjet printing conductive patterns on plastics
3) Copper Nanoparticles for Printed Electronics: Routes Towards Achieving Oxidation Stability (Review)
4) Formation of air-stable copper-silver core-shell nanoparticles for ink-jet printing
5) Synthesis of copper nanoparticles catalyzed by pre-formed silver nanoparticles

 

Our publications on silver based inks for printed electronics:

1) Printing Holes by a Dewetting Solution Enables Formation of a Transparent Conductive Film
2) Simulation and prediction of the thermal sintering behavior for a silver nanoparticle ink based on experimental input
3) UV crosslinkable emulsions with silver nanoparticles for inkjet printing of conductive 3D structures
4) Conductive patterns on plastic substrates by sequential inkjet printing of silver nanoparticles and electrolyte sintering solutions
5) Plasma and Microwave Flash Sintering of a Tailored Silver Nanoparticle Ink, Yielding 60% Bulk Conductivity on Cost-Effective Polymer Foils
6) Flexible transparent conductive coatings by combining self-assembly with sintering of silver nanoparticles performed at room temperature
7) Conductive Inks with a "Built-In" Mechanism That Enables Sintering at Room Temperature
8) Triggering the sintering of silver nanoparticles at room temperature
9) Transparent conductive coatings by printing coffee ring arrays obtained at room temperature
10) Simulation and prediction of the thermal sintering behavior for a silver nanoparticle ink based on experimental input
11) Making connections. Aqueous dispersions of silver nanoparticles form conductive inkjet inks
12) Ink-jet printing of metallic nanoparticles and microemulsions

 

Our publications on CNT based inks for printed electronics:

1) Inkjet printing of flexible high-performance carbon nanotube transparent conductive films by "coffee ring effect"
2) Flexible electroluminescent device with inkjet-printed carbon nanotube electrodes
3) Tunable inkjet printed hybrid carbon nanotubes/nanocrystals light sensor

An example for a use of printed electronics with the methods developed in our lab is presented in ReadSpot, a system developed for the OEA printed electronics competition that took place during the LOPEC 2017 Trade fair and conference, March 2017. Three methods were used to prepare functional NFC tags that can interact with a smartphone. This project presents a vision of what can be an excellent use of printed electronics and NFC technology, one that benefits humanity and has a commercial appeal. https://scholars.huji.ac.il/magdassi/book/readspot

ReadSpot

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ReadSpot. Is a system developed for the OEA printed electronics competition that took place during the LOPEC 2017 Trade fair and conference, March 2017. The system can identify specific products and read audibly important information such as the expiration date of a medication box. This will be helpful for anyone who has trouble reading, including people with visual impairment that literally have a hard time reading the small print, and tourists that don’t know the local language. This project presents a vision of what can be an excellent use of printed electronics and NFC technology, one that benefits humanity and has a commercial appeal.

NFC tags were prepared by printing antennas with three different innovative methods that enable printing of conductive patterns, and an NFC chip was attached to the antenna, enabling the formation of functional NFC tags. The NFC tags interact with a specially designed smartphone application named ReadSpot. The system was developed by three students from Prof. Magdassi's group in collaboration with a student from computer science school, all from the Hebrew University of Jerusalem. 

Method 1: Hydro-printing

A silver NP ink was printed by ink-jetting on a water soluble film and later hydro-printed onto 3D object. The connecting bridge was hydro-printed as well. An NFC chip was attached to the printed antenna with conducive glue, enabling the formation of NFC tag.

Read more about this at: Saada, Gabriel, et al. "Hydroprinting Conductive Patterns onto 3D Structures." Advanced Materials Technologies (2017).

 

Method 2: Copper salt particle ink

Copper salt particle ink (copper formate) was screen printed, followed by hot-pressing to decompose the copper salt to pure copper. An NFC chip was attached to the printed antenna with conducive glue, enabling the formation of a NFC tag

Read more about this at: Rosen, Yitzchak et al. "Copper interconnections and antennas fabricated by hot-pressing printed copper formate." Flexible and Printed Electronics (2017).

Method 3: Plasma treatment of ink-jetted copper complex ink

Copper complex ink is inkjet printed on plastic substrate followed by plasma treatment. A chip was attached using conductive glue, enabling the formation of a NFC tag.

Read more about this at: Farraj, Y., et al. "Plasma-Induced Decomposition of Copper Complex Ink for the Formation of Highly Conductive Copper Tracks on Heat-Sensitive Substrates." ACS Applied Materials & Interfaces (2017).

 

 

The ReadSpot Team:

Isaac (Yitzchak) Rosen

Yousef Farraj

Gabriel Saada

Adi Szeskin

App & Logo Design by Shira Rosen 

 

Picture of the ReadSpot Team

 

 

Solar Energy

Tharmo-solar coatings

The research goal is to develop solar coatings that can harvest the solar energy and convert it into heat and electricity. We developed (in collaboration with Prof. D. Mandler) coatings which are already in use by Brightsource in a large thermo-solar power plant, producing electricity for over 100,000 homes in California. Our present focus is on formation of selective coatings which have high absorption in solar spectrum, low emission in IR region, and resistant to high temperature, by a wet chemical method . The coatings are composed of three layers; absorber layer, IR reflecting layer, and antireflecting as well as protecting layer. The absorber layer absorbs solar light, the IR reflecting layer inhibits the thermal radiation, and the antireflecting layer increases the absorption and protect both absorber layer and IR reflecting layer from high temperature.

Transparent Conductive Electrodes

Alternatives to the most commonly used transparent electrodes, indium tin oxide (ITO), are highly required by the printed electronics industry, for applications such as touch screens and solar cells. The demand for low-cost materials and technologies is mainly due to the complexity of the currently used methods and the industrial trends towards flexible and wearable electronics, which ITO is not suitable since it is a brittle material.  For this reason, the number of reports on new materials and methods to fabricate transparent conductive coatings (TCC), have increased dramatically for the past 5 years. A promising approach to obtain a TCC with a very low sheet resistance is based on using metallic nanomaterials. The intrinsic high conductivity of metals such as silver, copper and gold, and carbon nanotubes, enables to obtain TCC with sheet resistance as low as 1-10 Ohms per square. We have developed several new approaches which are based on self-assembly, controlled wetting  and inkjet printing to fabricate transparent patterns composed of narrow lines (<10 µm).The various approaches will be briefly described in the following sections and more information can be found in: Nanoscale 6, no. 11 (2014): 5581-5591.

Coffee stain 2D ring array

We have developed an ink and a fabrication process for direct patterning of TCCs, by ink-jet printing silver nanoparticles, which spontaneously forms arrays of transparent rings due to the coffee ring effect (Fig. 1). The diameter, height and width of the rings can be tailored according to the specific requirements of conductivity and transparency of a device such as smart phone's touch screen. These findings were published in ACS nano 3.11 (2009): 3537-3542. This research led to the establishing a new start-up company, Clear-Jet, through an agreement with Yissum, the tech transfer company of The Hebrew University.

Silver rings comprising transparent electrode

 Fig. 1:  A TCC composed of array of printed "coffee rings"

Transparent conductive grids

TCCs formed by a grid patterns are becoming commercially available. Among the many companies that are utilizing this approach are: POLYIC, Toray and Rolith. Typical technologies to achieve conductive transparent metal grids are based on photolithography, direct printing, embossing and as reported by our research group, by combining low temperature sintering and self-assembly. The method is based on evaporative lithography process which is performed directly onto plastic substrates. In essence, a droplet containing silver nanoparticles is placed on top of a mesh, instantaneously spreading over the mesh and the plastic substrate, forming a grid composed of the nanoparticles. The nanoparticles are sintered at low temperature by a chemical sintering process that we developed. For more information see: Journal of Materials Chemistry 21.39 (2011): 15378-15382 and Nanoscale 6.9 (2014): 4572-4576 and Journal of Materials Chemistry A2.38 (2014): 16224-16229.

These transparent grids were integrated into electroluminescent and electrochromic devices. Recently, this process was further utilized with a perovskite material to form a semi-transparent solar cell: Adv. Mater. Interfaces, 2: (2015) . doi: 10.1002/admi.201500118.

Transparent conductive grid

Fig 2: Transparent conductive grid

A new approach was developed to fabricate patterned transparent conductive electrodes by direct printing of “2D holes” with controllable diameters onto a wet thin film composed of metal nanoparticles (Fig.3). The holes are formed by inkjet printing a de-wetting liquid, which pushes away the metal nanoparticles, thus forming a transparent array of interconnected conductive rings. The array of interconnected rings can be printed in a macro patterns in any required shape, such as honeycomb, diamond shape or rectangular grids: ACS applied materials & interfaces 6.21 (2014): 18668-18672

 

array of interconnected rings can form a macro pattern

 Fig. 3: TCC composed of array of printed "holes"