Fully R2R gravure printed smart tags and related web handling challenges

Although a smart tag which can communicate with a smart phone via NFC (Near Field Communication) has been considered as a core tool for bringing up the ubiquitous society, the difficulties in integrating 13.56 MHz RFID (Radio Frequency Identification), sensors and signage altogether on plastic foils with extremely low cost (< 0.5 $) nullify its role for the realization of the ubiquitous society. In this presentation, three key issues of R2R gravure such as overlay printing registration, web tension control and surface roughness of printed layers will be introduced as challenges to be overcome in the production of inexpensive smart tags on flexible plastic foils. The integration of those devices (RFID, sensors and signage) on the plastic foils will be successfully demonstrated using fully gravure printed 96 bit RFID tag, RF-QR tag and RF-Sensors. Those tags contains printed key device units such as 13.56 MHz modulating TFT, digital logic gates, 96 bit memory, cyclic voltammetry, electrochromic display, and rectifier for the wireless power transmission via NFC (13.56 MHz). The detail specifications of R2R gravure and printed key device units for the printed smart tags will be presented as well

Fully roll-to-roll gravure printable wireless (13.56 MHz) sensor-signage tags for smart packaging

Integration of sensing capabilities with an interactive signage through wireless communication is enabling the development of smart packaging wherein wireless (13.56 MHz) power transmission is used to interlock the smart packaging with a wireless (13.56 MHz) reader or a smart phone. Assembly of the necessary componentry for smart packaging on plastic or paper foils is limited by the manufacturing costs involved with Si based technologies. Here, the issue of manufacturing cost for smart packaging has been obviated by materials that allow R2R (roll-to-roll) gravure in combination with R2R coating processes to be employed. R2R gravure was used to print the wireless power transmission device, called rectenna (antenna, diode and capacitor), and humidity sensor on poly(ethylene terephtalate) (PET) films while electrochromic signage units were fabricated by R2R coating. The signage units were laminated with the R2R gravure printed rectenna and sensor to complete the prototype smart packaging

Screen-Printed Flexible Bandstop Filter on Polyethylene Terephthalate Substrate Based on Ag Nanoparticles

We present a low-power, cost-effective, highly reproducible, and disposable bandstop filter by employing high-throughput screen-printing technology. We apply large-scale printing strategies using silver-nanoparticle-based ink for the metallization of conductive wires to fabricate a bandstop filter on a polyethylene terephthalate (PET) substrate. The filter exhibits an attenuation pole at 4.35 GHz with excellent in-and-out band characteristics. These characteristics reflect a rejection depth that is better than −25 dB with a return loss of −0.75 dB at the normal orientation of the PET substrate. In addition, the filter characteristics are observed at various bending angles (0°, 10°, and 20°) of the PET substrate with an excellent relative standard deviation of less than 0.5%. These results confirm the accuracy, reproducibility, and independence of the resonance frequency. This screen-printing technology for well-defined nanostructures is more favorable than other complex photolithographic processes because it overcomes signal losses due to uneven surface distributions and thereby reveals a homogeneous distribution. Moreover, the proposed methodology enables incremental steps in the process of producing highly flexible and cost-effective printed-electronic radio devices

Control of registration accuracy of R2R gravure for fabricating inexpensive electronic devices

The errors of the overlay printing registration in roll-to-roll (R2R) gravure are generated from many sources such as uneven web tension, thermal expansion and contraction of plastic web, uneven impression roll pressure, slipping the web, uneven circumference of the roll, unmatched speed between web transfer, printing roll, and so forth. Among those things, the most influential factors to exert on overlay printing registration in R2R gravure should be defined and analyzed to provide servomechanism to control at least ±20 µm of registration accuracy of R2R gravure with more than 4 m/min of web transfer speed. In this paper, we would like to present the general way of control system of R2R gravure to maintain the overlay printing registration of ±20 µm under various web transfer speeds, roll pressure and uneven web tension

Fully gravure printed complementary carbon nanotube TFTs for a clock signal generator using an epoxy-imine based cross-linker as an n-dopant and encapsulant.

Printed p-type single walled carbon nanotube (SWCNT) based circuits exhibit high power dissipation owing to their thick printed dielectric layers (&gt;2 μm) and long channels (&gt;100 μm). In order to reduce the static power dissipation of printed SWCNT-base circuits while maintaining the same printing conditions and channel lengths, complementary metal-oxide-semiconductor (CMOS) based circuits are more ideal. These circuits, however, have not been successfully implemented in a scalable printing platform due to unstable threshold voltages of n-doped SWCNT based thin film transistors (TFTs). In this work, a thermally curable epoxy-imine-based n-doping ink is presented for achieving uniform doping and sealing of SWCNT layers by gravure printing. After printing the n-doping ink, the ink is cured to initiate a cross-linking reaction to seal the n-doped SWCNT-TFTs so that the threshold voltage of the n-doped SWCNT-TFTs is stabilized. Flexible CMOS ring oscillators using such n-doped SWCNT-TFTs combined with the intrinsically p-type SWCNT-TFTs can generate a 0.2 Hz clock signal with significantly lower power consumption compared to similarly printed p-type only TFT based ring oscillators. Moving forward, this CMOS flexible ring oscillator can be practically used to develop fully printed inexpensive wireless sensor tags

Silver-Nanoparticle-Based Screen-Printing and Film Characterization of a Disposable, Dual-Band, Bandstop Filter on a Flexible Polyethylene Terephthalate Substrate

This paper presents a silver-nanoparticle-based, screen-printed, high-performance, dual-band, bandstop filter (DBBSF) on a flexible polyethylene terephthalate (PET) substrate. Using screen-printing techniques to process a highly viscous silver printing ink, high-conductivity printed lines were implemented at a web transfer speed of 5 m/min. Characterized by X-ray diffraction (XRD), optical microscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM), the printed lines were shown to be characterized by smooth surfaces with a root mean square roughness of 7.986 nm; a significantly higher thickness (12.2 μm) than the skin depth; and a high conductivity of 2×107 S/m. These excellent printed line characteristics enabled the implementation of a high-selectivity DBBSF using shunt-connected uniform impedance resonators (UIRs). Additionally, the inductive loading effect of T-shaped stubs on the UIRs, which were analyzed using S-parameters based on lumped parameter calculations, was used to improve the return losses of the geometrically optimized DBBSF. The measured minimum return loss and maximum insertion loss of 28.26 and 1.58 dB, respectively, at the central frequencies of 2.56 and 5.29 GHz of a protocol screen-printed DBBSF demonstrated the excellent performance of the material and its significant potential for use in future cost-effective, flexible WiMax and WLAN applications

Roll-to-roll gravure printed smart food package to replace the "use-by" date system of foods

The implementation of internet of things (IoT) to the food industry offers a great deal, accompanying each functional unit from production to the consumption to ensure the quality of a particular food item. Among several factors, the fluctuation in temperature through the cold chain are prone to the propagation of foodborne pathogens and is considered as a leading factor to reduce the shelf life. Therefore, a smart food package, which dynamically monitors the time-temperature history (TTH) throughout the food logistics will be very crucial to access meaningful data regarding the quality and safety of a food package. This smart packaging system utilizing NFC function of the smartphone to access quality information of a food item not only prevents from the blind disposal of consumable items if the quality is good enough to consume but also prohibits the consumers from its usage if the quality is bad, which at present is heavily relied upon the due date. However, the cost issue associated with the manufacturing of radio frequency identification (RFID) prohibits these systems from implementing to a smart packaging system for everyday consumable food products. To resolve this, we incorporated fully scalable, high throughput, and flexible roll-to-roll (R2R) gravure printing system to realize the NFC antenna, flexible printed circuit board (FPCB), a thermistor, and a battery. We successfully demonstrate the printing of NFC antenna as well as the thermistor continuously from the two printing units at a practical printing speed of more than 6 m/min on a polyimide (PI) substrate. The printing conditions such as nip-roll pressure, blade angle was optimized to 6 kgf and 9°, respectively to ensure the quality printing of both antenna and the thermistor, whereas the viscosity of the silver nanoparticle ink for realizing antenna was 1000 cP. The Si-chip transponder was embedded to the printed NFC tag, by using a daughter board, to record the temperature at custom-defined time instants throughout the cold chain

Photonic curing for enhancing the performance of roll-to-roll printed electronic devices

The advent in printing technology promotes the possibility of roll-to-roll manufacturing process for low-cost, high throughput, and large area printing of the electronic devices in flexible substrate materials. However, the conductivity of the nanoparticle ink being utilized for printing process is the major challenge to compete with the existing silicon-based technology in terms of the device performance. A number of post-processing steps were proposed over the year to enhance the conductivity and among them thermal curing is the easiest solution so far. However, in high speed R2R processing system, thermal curing is not compatible owing to its long curing time or high temperature required to attain the desired conductivity. To overcome the issues of thermal curing, Intense Pulsed Light (IPL) photonic sintering has shown a promising capability to sinter the printed conducting patterns in milliseconds. Furthermore, photonic sintering can either be embedded together with R2R system during printing or in conjunction with the thermal curing is viewed as a viable approach to improve the conductivity of printed pattern. In this work, we studied different photonic sintering techniques and compared the results with the conventional thermal curing methodology in R2R printed near-field communication (NFC) antenna patterns. Experimental results showed that photonic sintering can reduce the resistance of the antenna more effectively than thermal curing even on polyethylene terephthalate (PET) with low melting point. The limitations of the present sintering techniques were highlighted from the prospect of future enhancement