Based on an organic photodetector array and a printed copper-grid bottom electrode

TNO at Holst Centre, The Netherlands, and Asahi Kasei, Japan, announce the development of a touchless user interface for displays that is based on an entirely new technological concept. It is the result of a three-year collaboration project by the Dutch R&D institute and the Japanese multinational. Holst Centre developed a near-infrared sensitive transparent image sensor, using a printed copper-grid bottom electrode developed by Asahi Kasei. The imager can be combined with a variety of commercially available displays, as a penlight-controlled or a gesture-controlled touchless user interface. A detailed technical description of the new concept has recently been published in Nature Electronics.

During the COVID-19 pandemic people worldwide were very much aware of contamination risks in public spaces. This enhanced the demand for touchless interaction with screens in public spaces, like ATMs, payment terminals, and self-check-in terminals at airports. Other applications with high contamination risks are, for instance, hospital equipment and food production.

A new approach

The currently available touchless user interfaces typically show some shortcomings, which are dealt with in the newly developed concept. Gesture-based touchless user interfaces typically rely on near-infrared cameras. However, such systems are often hampered by a limited field of view and high-accuracy calibration requirements. The touchless user interface now demonstrated is based on a visually transparent near-infrared-sensitive organic photodetector array, and can be used on top of a display. Optical transparency is achieved by using a printed copper grid as a bottom transparent conductive electrode and an array of patterned organic photodetector subpixels. Electro-optical modelling is used to optimize the design of the near-infrared image sensor, leading to a state-of-the-art device with a transparency of more than 70%, suitable for commercial applications. The imager can be used as a penlight-controlled and a gesture-controlled touchless user interface, in combination with a variety of commercially available displays.

Complementary expertise

TNO at Holst Centre has world-class expertise in flexible electronics. Solving societal challenges by co-developing technological innovations with industrial partners, is at the core of Holst Centre’s identity. Asahi Kasei is ideally positioned to bring this innovation to market, using its precision micro-printing processes and materials for printed copper-grid electrodes.

The future

The collaboration project was a great success in all respects. Therefore, Asahi Kasei and TNO at Holst Centre will continue their fruitful collaboration in the future, on different application domains, like healthcare and energy. Albert van Breemen, Program manager at Holst Centre: “Combining the technology of Asahi Kasei with our expertise and know how of design has significantly advanced the application domain of touchless interfaces. The excellent transparency and ease of scalability enables its use with a variety of different displays including ATMs, electric signage, and interactive whiteboards — without size-limitation and calibration requirements. We look forward to working together further in the future.”

Read the full article in Nature Electronics.