Development of Electronic Skin that Changes Brightness According to Pressing Force

– 'Research on visualization of touch through ionic light-emitting materials' published in Advanced Materials –

 (From left) Professor Kang Moon Sung and Lee Jong Ik in Integrated Masters with a PhD course


A research team from the Department of Chemical and Biomolecular Engineering, led by Professor Kang Moon Sung (corresponding author Professor Kang Moon Sung, first author Lee Jong Ik, Researcher in Integrated Masters with a PhD Course), has developed a type of 'smart light-emitting electronic skin' that responds with microscopic changes in light to changes in force, such as pressing or stretching.


'Smart tactile interface technology,' which provides visible feedback in real time in response to input from a user's pressing or stretching, can be usefully applied to next-generation user-friendly immersive technologies, such as flexible touchscreens and buttonless displays. However, the existing electronic skin technology, which provides visual feedback by sensing pressure and emitting light, requires a pressure-sensing device and light-emitting device to produce a proper response, along with a complex circuit system to connect the different elements. In addition, demand has emerged for a technique that arranges a sensing device and a light-emitting device with a high degree of integration in order to finely distinguish the position where pressure is applied.

Accordingly, the research team designed a type of electronic skin with an electrochemical luminescent material applied to a stretchable polymer material, associated with 'marine plankton,' achieving changes in luminescence intensity in response to the stimulus created by the flow of seawater. The newly designed electronic skin uses the principle that the luminance of light (intensity of light per unit area) varies based on the distribution of ions contained in a material, according to the strength of the force only in the parts receiving pressure. Through this, a light-emitting material in the form of a thin film that responds to the location and intensity of the applied stimulus with real-time changes in light was realized without an individually configured sensing device and light-emitting device and without complex circuits to connect them.

  Schematic diagram of smart photonic electronic skin that changes the luminance of light based on pressing (pressure) or pulling (tensile) external stimuli

The electronic skin made in this way was able to emit light with different degrees of luminance under various pressures (0 to 60 kPa) created through human touch. In addition, the developed electronic skin responded with a change in the luminance of the emitted light even to the stretching stimulus and, interestingly, the luminance of the light increased in proportion to the stretching stimulus. This is an advantageous method for easily distinguishing the intensity of stretching stimulation, which is different from the previously reported general visual feedback for electronic skin.

The results of this research conducted with the support of the Mid-Career Researcher Program for Individual Basic Research in Science & Engineering, promoted by the Ministry of Science and ICT and the National Research Foundation of Korea, were published online at midnight (KST) on June 2nd in 'Advanced Materials (IF = 27.398),' an international scientific journal in the field of materials science.

Regarding this work, Professor Kang said, "This research is very meaningful in suggesting a new tactile signal-visual signal conversion method based on various element technologies from chemical engineering, such as rheological properties of polymer materials, ion and material transfer phenomena, and electrochemical reactions."

 Paper Title: Visco-Poroelastic Electrochemiluminescence Skin with Piezo-Ionic Effect

 Paper Link: