Particle bad conductive silver ink customized for ink jet printing on
cellulo electro-active paper
Mohammad Abu Hasan Khondoker a, Seong Cheonl Mun a, Jaehwan Kim*a
a Department of Mechanical Engineering, Inha University, 253 Yonghyun-Dong, Nam-Ku
计算机专业
Incheon 402-751, Korea
ABSTRACT
A previously synthesized silver nanoparticle bad conductive silver ink was ud in this work to print conductive electrodes on cellulo electro-active paper (EAPap) by using an inkjet printer. Then, Inkjet printed cellulo EAPap experienced a post-deposition heat treatment-sintering process to enhance electrical conductivity of printed electrodes by converting tho printed patterns into continuous metallic state. The dependences of electrical bulk resistivity of printed electrodes on both sintering temperature and sintering time were checked. It was found that, higher sintering temperatures and long
er sintering process result lower resistivity. In addition, the uniformity of the thickness of printed electrodes through transver direction and the relationship between thickness and the number of printing also had been analyzed. Tho printed electrodes also showed very good adhesion on cellulo EAPap.
Keywords: Conductive silver ink, inkjet printing, cellulo EAPap, printed electrodes, electrical resistivity, sintering process
1. INTRODUCTION
As a natural biodegradable polymer, cellulo is everywhere. Huge biomass production of cellulo made it as inexhaustible raw material for environmentally friendly and biocompatible products [1]. The discovery of cellulo as a smart material dates back to 2006 when Kim et. al. reported the actuation effect of cellulo electro-active paper (EAPap) [2]. Cellulo EAPap with printed electrode has potentiality in microelectromechanical system (MEMS) application. Electrodes can be inkjet printed by microscale patterning of lines or dots by ejecting tiny droplets of 10–100 µm diameter [3]. Moreover, promising technologies, such as inkjet printing/electrohydrodynamic jet printing (EHDP)/drop-on-demand patterning, have been paid attention to print conductive patterns for fabrica
ting flexible, lightweight, disposable devices and polymer bad flexible microelectronics [4–7]. They are one-step process and do not need coating and etching.
In this work, an inkjet printer was ud to find best printing quality by changing veral printing conditions (no. of nozzle, position of nozzle, firing voltage etc.) and silver ink content. Finally, around 40 µm wide electrodes were successfully printed on cellulo EAPap with synthesized silver ink. Cellulo EAPap’s were prepared from regenerated cellulo films by the procedure described elwhere [8-10].
四六级准考证打印入口2. EXPERIMENTAL
2.1 Synthesis process of silver ink
dw是什么意思Firstly, silver nanoparticles were synthesized through modified polyol process [11]. In brief, 1.02 g of silver nitrate and 10.2 g of polyvinylpyrrolidone (PVP) were completely dissolved in parate ethylene glycol (EG). PVP solution was heated up to an appropriate temperature (100–160 °C) in an oil bath. Then the temperature was kept fixed. When it turned out to be light yellow, silver nitrate solution was then injected slowly into this solution while stirring vigorously. Then this solution was allowed to be gently stirred for 4 h at fixed temperature. This step results in the formation of PVP-cap
ped silver nanoparticles. The resulting solution was then disperd in ethanol. Finally, the disperd solution was centrifuged at 9000 rpm for 60 min.
why是什么意思*jaehwan@inha.ac.kr; phone 82-32-874-7325; fax 82-32-832-7325;
Nanonsors, Bionsors, and Info-Tech Sensors and Systems 2013, edited by
Vijay K. Varadan, Proc. of SPIE Vol. 8691, 86910Q · © 2013 SPIE
CCC code: 0277-786X/13/$18 · doi: 10.1117/12.2010095
This washing step was repeated three times and the final residue of silver nanoparticles with size less than 50 nm was obtained. Then previous rearch work [12] was followed to synthesize silver ink from silver particles. A very small amount of viscous hydroxyethyl-cellulo (HEC) solution and diethylene glycol (DEG) were added to the residue of silver nanoparticles. Here, HEC acts as a viscosifier to increa the viscosity [13] and DEG acts as a surfactant to lower the surface tension of the solution. Then the solid content ranging of about 45 % was adjusted by adding 50-50% solution of deionized water and DEG. Finally, the conductive silver ink was achieved by sonicating for 1 h and subquent ultrasonic homogenizing for 10 min with a power level of 30 %.
2.2 Inkjet printing on cellulo EAPap
A FUJIFILM Dimatix (Santa Clara, USA) DMP-2800 ries inkjet printer was ud in this work. Firstly, silver ink was injected into printer cartridge. Then that cartridge was kept in refrigerator for at least 2 hours to make sure that there is no tiny air bubble inside that ink. After adjusting some printing criterion to the optimal conditions, electrodes were printed on cellulo EAPap. Then, tho electrodes underwent through heat treatment (i.e. sintering) at different temperatures for different time lengths.
3. RESULT AND DISCUSSION
3.1 Electrical resistivity
The bulk resistance across printed electrodes was measured by means of digital multimeter. Width and thickness of printed electrodes were measured from scanning electron microscopic (SEM) images. Finally, the bulk resistivity of printed electrodes was estimated. The resistivity varies with sintering temperature and sintering time. From figure 1, with higher sintering temperature, resistivity decreas. The longer sintering process also reduces resistivity of printed electrodes.
0100
200
300
fee400
500600700800
900
10001100
R e s i s t i v i t y (Ω-c m )Sintering Temperature (°C)十分钟看懂中国
Figure 1: Electrical resistivity (Ω-cm) of printed electrodes versus Sintering temperature (C) and Sintering time (min)
By analyzing this illustration, after sintering for 20 min, resistivity drastically reduced. Another dramatically diminution in resistivity was obrved after increasing sintering temperature. For sintering process with 10 min and 15 min, when sintering temperature raid from 180 °C to 200 °C resistivity plummeted from 615 µΩ-cm to 183 µΩ-cm and from 630 µΩ-cm to 104 µΩ-cm, respectively. More importantly, regardless of sintering time the resistivity after heating at 230 °C reaches a convergent value around 20~30 µΩ-cm. Though the minimal resistivity, 21.6 µΩ-cm was achieved from 25
min long sintering at 230 °C but we found the optimal conditions are 20 min and 200 °C. With tho optimal conditions, the resulting resistivity was 23.5 µΩ-cm, only 9% higher than minimum resistivity.
3.2 Printing on different substrates
Two commercially available cellulo films and one laboratory prepared cellulo films were ud to print electrode using synthesized silver ink. In figure 2, the surface SEM images of printed electrodes on three different cellulo films are shown. Though printed electrode on a commercial cellulo film shown good quality than laboratory prepared cellulo film in terms of line uniformity but in ca of other commercial cellulo film the jetted ink disperd on the surface resulting poor quality printing.
Figure 2: Surface SEM images of inkjet printed lines on (a) a commercial cellulo film and (b) laboratory prepared cellulo film
3.3 Electrode line thickness and width
The thickness and widths of electrode lines were measured from cross-ctional and surface SEM images, respectively. The variation of line thickness with the number of printing was analyzed graphically. The line thickness were measured up to four times printing. After each printing, the electrodes were allowed to dry. After drying, another line was drawn on the same electrode line. The line thickness increas almost linearly with the number of printing. The line thickness from single printing was only around 0.5 µm, which is more than three times (1.5 µm) for electrodes printed four times.
4. CONCLUSIONS
Firstly, silver ink was prepared and ud in inkjet printer to print conductive silver electrodes. Then, the resistivity of printed electrodes and other criterion were analyzed. Higher sintering temperature and higher sintering time resulted lower electrical resistivity. At higher temperature the capping agent PVP was removed from silver electrodes and the silver nanoparticles make continuous conductive network. As a result, longer sintering temperature results higher electrical conductivity. With number of printing, the thickness of silver electrode increas. The synthesized silver ink can be ud in flexible, micro-electronics.
Acknowledgements
生活哲理散文
This rearch was supported by the National Rearch Foundation, Ministry of Education, Science and Technology, Republic of Korea.
REFERENCES
[1]Klemm, D., Heublein, B., Fink, H.-P. and Bohn, A., “Cellulo: fascinating biopolymer and sustainable raw
material,” Angew. Chem., Int. Ed. 44, 3358-3393 (2005).
[2]Kim, J., Yun, S. and Qunaies, Z., “Discovery of cellulo as a smart material,” Macromolecules 39, 4202-4206
(2006).
[3]Ryu, B.-H., Choi, Y., Park, H.-S., Byun, J.-H., Kong, K., Lee, J.-O. and Chang, H., “Synthesis of highly
concentrated silver nanosol and its application to inkjet printing,” Colloid Surface A 270-271, 345-351 (2005).
[4]Liu, Z., Su, Y. and Varahramyan, K., “Inkjet-printed silver conductors using silver nitrate ink and their
electrical contacts with conducting polymers,” Thin Solid Films 478, 275-279 (2005)
[5]Lee, H.-H., Chou, K.-S. and Huang, K.-C., “Inkjet printing of nanosized silver colloids,” Nanotechnology 16,
we just laugh about it2436-2441 (2005)
[6]Yu, J.H., Kim, S.Y. and Hwang, J., “Effect of viscosity of silver nanoparticle suspension on conductive line
patterned by electrohydrodynamic jet printing,” Appl. Phys. A-Mater. 89, 157-159 (2007)
[7]Rahman, K., Ali, K., Muhammad, N. M., Hyun, M.-T. and Choi, K.-H., “Fine resolution drop-on-demand
electrohydrodynamic patterning of conductive silver tracks on glass substrate,” Appl. Phys. A-Mater. DOI:
10.1007/s00339-012-7267-x (2012).
[8]Yun, S., Chen, Y., Nayak, J. N. and Kim, J., “Effect of solvent mixture on properties and performance of
electro-active paper made with regenerated cellulo,” Sensor Actuat. B-Chem. 129, 652-658 (2008).
[9]Kim, J. and Seo, Y. B., “Electro-active paper actuators,” Smart Mater. Struct. 11, 355-360 (2006).
[10]Kim, J., Song, C. S. and Yun, S., “Cellulo bad electro-active papers: performance and environmental
effects,” Smart Mater. Struct. 15, 719-723 (2002).
[11]Zhao, T., Sun, R., Yu, S., Zhang, Z., Zhou, L., Huang, H. and Du, R., “Size-controlled preparation of silver英语发音词典
nanoparticles by a modified polyol method,” Colloid Surface A 366, 197-202 (2010).
影响英文
[12]Khondoker, M. A. H., Mun, S. C. and Kim, J., “Synthesis and characterization of conductive silver ink for
electrode printing on cellulo film,” Appl. Phys. A-Mater. DOI: 10.1007/s00339-012-7419-z (2012).
[13]Russo, A., Ahn, B. Y., Adams, J. J., Duoss, E. B., Bernhard, J. T. and Lewis, J. A., “Pen-on-paper flexible
electronics,” Adv. Mater. 23, 3426-3430 (2011).
