서강대학교

초록/요약

Among electrode patterning techniques for a printed circuit board such as soft lithography, roll-to-roll printing, screen printing, inkjet printing is attractive to general users due to easy operation, high accuracy and low cost as well as small working space in a desktop scale. Industrial inkjet printing technology has already opened a new research field of the printing electronics, which are required in various minimizing integrated circuits and electronics such as displays, sensors and cellular phone. For inkjet printing it is possible to print on various substrates depending on the deposited materials as long as in form of ink. Therefore it is critical to study the ensemble of a conductive ink material and a substrate simultaneously to obtain good printing patterned electrodes. Here we will present the development of two complemental inks, silver metal-based and carbon nanotube-based, especially well coupled only on paper substrate and demonstrate its applications of paper electronics using a personal and office inkjet printer. Synthesis of silver precursor and carbon nanotube inks has been accomplished by careful considering for printing such that proper viscosity, surface tension and nanoparticle size were well fitted to the diameter and the piezoelectric jetting pressure of a nozzle as those of normal printer ink. For sliver precursor ink, to exclude any thermal treatment the chemical reduction agent was also employed and formulated in an ink form and a pre-coated with polymer by using the electrospinning to help good adsorption, resulting in the high conductivity reached to the surface resistance of 2.4 Ω/sq, which is a few percent of that of bulk silver. Carbon nanotube was fabricated by using dispersant, ball-milling, centrifugal separation and membrane filtering, subsequently, resulting in the high conductivity of about 130 Ω/sq, which is the smallest value in the world as far in our knowledge. By using these inks and printing process, we can fabricate electric circuit, inductive sensor, paper display and bio-sensor. By printing many patterned electrodes, we achieved paper electronic applications successfully, revealing that our conductive inks are the first prototype of home paper electronics.