Conducting inks to make fine circuits: Creating fourth-generation interactive paper

Sweden uses conductive inks to make fine circuits: creating fourth-generation interactive paper

A few days ago, a new type of paper billboard was being exhibited at Central University in Sweden. On this type of billboard, touch sensors and speakers are printed. Visitors can touch the billboards to make music, or play classic dialogues in comedy programs. Regardless of appearance or feel, there is no difference between such billboards and ordinary paper. The only difference is that this type of paper is more interactive.

Mikal Guliksen, a researcher at the Central University of Sweden, and his colleagues believe that the first generation of paper is used for presentation and recording, the second generation of paper is used for packaging, and the third generation of paper is for the needs of health. The fourth-generation paper should have the function of interacting with humans. The billboards being exhibited are what they call fourth-generation paper. This type of billboard is almost entirely made of paper materials. In order to make the paper interactive, researchers have applied a new type of conductive ink. The ink contains silver particles and has good conductivity. It is printed with this type of ink. The pattern itself is a current loop.

The billboard has a three-layer structure. The bottom layer uses a 3 cm-thick rigid super-thick cardboard as the board base. The circuit printed on the paper with conductive ink is on the middle layer, and the outermost layer is the appearance of the billboard. The middle layer circuit connects the power supply and the microelectronic controller. In this way, the billboard can automatically play, pause and play back the musical sound after the corresponding force sensor is touched.

Billboards interact with viewers through force sensors, speakers, and the circuitry that connects them. The so-called force sensor is actually a fine circuit printed with conductive ink, similar to the touchpad of a laptop computer. The current in the circuit changes with the touch of a finger, which produces a sensing effect. The production of the speaker is somewhat complicated. First, the electromagnet is printed with conductive ink, and then the paper is raised to form a resonance chamber, so that the electromagnet can make a sound through vibration.

In the future, people can also use semiconductor polymers to print a variety of integrated circuits on paper, giving this paper more interactive features.