The main group research fields are formation and stabilization of inorganic and organic nanomaterials, ink formulation, formation of delivery systems, and their material application in the field of 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.
Based on research projects, commercial activities are performed leading to worldwide sales and establishing new companies.
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. For a review see: A. Kamyshny and S. Magdassi, Conductive Nanomaterials for Printed Electronics, Small, 10, 3515–3535, (2014). 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.
In our research group we focus on, synthesis and formulation of conductive inks and on functional printing technologies (mainly inkjet). 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. The conductive materials that we focus on are silver and copper nanoparticles, carbon nanotubes and organometallic compounds. We also investigate low temperature sintering of nanomaterials that enable printing conductors on plastic substrates (see: merging of metal nanoparticles driven by selective wettability of silver nanostructures, Conductive inks with a "built-In" mechanism that enables sintering at room temperature, triggering the sintering of silver nanoparticles at room temperature)
Additional activity in this field is directed towards fabrication of transparent conductive films, that can be utilized in optoelectronic devices such as smartphones and solar cells (see: Flexible transparent conductive coatings by combining self-assembly with sintering of silver nanoparticles performed at room temperature, transparent conductive coatings by printing coffee ring arrays obtained at room temperature.)
The field of additive manufacturing 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 rapid prototyping to medical devices. Our research is focused on developing new materials for most types of 3D printing technologies, including conductive inks, ceramic materials, metals and shape memory polymers. Two examples are described in the following sections:
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 nanoparticles that are sintered by a chemical sintering, resulting in a 3D conductive structure (Fig.1). 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.)
3D printing of shape memory materials
Until now, shape memory polymers were never used in the field of 3D printing or flexible electronics due to inadequate processing technologies. We developed a new process and inks which enable printing of oligomers in a DLP printer, to generate high-resolution three-dimensional (3D) shape memory structures (Fig. 2). We also demonstrated how these printed structures can be further utilized for constructing and 4D and flexible electronic devices (see: Adv. Mater. doi:10.1002/adma.201503132).
Fig. 2: 3D printed structures changing shape upon heating due to the shape memory polymer.
Drug Delivery and medical imaging
This field of research is focused on preparation of nano and micro structures such as organic nanoparticles, for application in various fields such as medical 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 were prepared by using only non-covalent attachment of probe molecules, see Journal of biomedical nanotechnology 10.6 (2014): 1041-1048.
Other examples are nanodroplets of pomegranate seed oil (PSO), for prevention and treatment of neurodegenerative diseases (in collaboration with Prof. R. Gabizon, Hadassha Hospital, see: Nanomedicine. (2014) Apr 2. pii: S1549-9634(14) 00133-6), and nanoparticles of water insoluble drugs which are prepared by evaporating volatile microemulsions (see Int. J. Pharmaceutics, 393,230–237, (2010).)