Inkjet printer produces color light sensors

printable light sensors
Karlsruhe Institute of Technology (KIT) has developed printable light sensors that can distinguish between colors. (Noah Strobel, KIT)

At the InnovationLab in Heidelberg, scientists of Karlsruhe Institute of Technology (KIT) have developed printable light sensors that can see colors.

New technologies will increase the demand for optical sensors for various applications, including visible light communication (VLC). VLC uses interior lighting of buildings for optical communication. In terms of security, speed, and accessibility, this technology has several advantages over conventional transmission processes, such as WLAN or Bluetooth.

"Our research is based on the idea of combining the advantages of a special type of materials, namely, organic semiconductors, and their production by printing processes," said Dr. Gerardo Hernandez-Sosa of KIT's Light Technology Institute, one of the authors of the publication.

Some semiconducting materials react to light by changing their conductivity. Light intensity can be measured as electrical current. Using a printer, some materials can be applied to a carrier material like printing ink. These materials react to varying wavelengths, which means that they can distinguish colors.

The Hernandez-Sosa team has succeeded in finding a composition of materials suited for use as wavelength-sensitive light detector as well as for printing onto flexible carriers. Printing can be performed on very small to very large areas. The layout can be designed easily with the help of a computer. "High numbers of these photodetectors of any design can be produced on flexible, light materials. Hence, they are particularly suited for mobile devices," first author Noah Strobel points out.

Printing of semiconductor components has a considerable potential for future applications. The industry is already investing huge dollars in producing printed OLED displays for TVs and smartphones. Production of printed light detectors has also reached the industrial scale. It is therefore highly probable that these elements will be used in many applications in the future.