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