A touchless user interface based on a near-infrared-sensitive transparent optical imager

Abstract

Touchless user interfaces that are based on gestures typically rely on near-infrared cameras. However, such systems are often hampered by their limited field of view and high-accuracy calibration requirements. Here we report a touchless user interface that 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 image sensor, leading to a photodetectivity of approximately 1012 Jones at 850 nm and a high visible-light transmittance of 70%. We show that the imager can be used as a penlight-controlled and gesture-controlled touchless user interface when combined with a commercial display.

Roadmap on printable electronic materials for next-generation sensors

“…(c) Visually transparent near-infrared-sensitive organic photodiodes-based arrays placed in front of a laptop display for gesture recognition applications. Reproduced from [15]. CC BY 4.0.…”

“…With the advent of the Internet-of-Things era, however, new applications emerge in which light sensing is integrated in everyday objects and this calls for novel photoactive materials and processes. Emerging application examples include transparent imagers for smart glass applications [15], in-display biometric imagers [16][17][18] and photonic patches that can measure vital signs [19,20]. These applications typically require large-area and/or flexible substrates.…”

Semitransparent Near‐Infrared Organic Photodetectors: Flexible, Large‐Area, and Physical‐Vapor‐Deposited for Versatile Advanced Optical Applications

“…[1,2] The visible see-through property of OPDs enables their integration with other electronic devices, creating well-integrated optical sensing systems for applications like augmentation reality (AR) virtual reality (VR) headsets/glasses, head-up-displays (HUD), touchless screens or smart windows. [3][4][5] In addition, with the rapid development of remote sensing and imaging techniques, there is a growing need to incorporate multiple photo-sensing modules into a single system to gather more information from the target. For instance, drones used in agriculture monitoring require both multispectral imaging and compact size.…”

“…Recently, Bhatnagar et al [20] designed a semitransparent metal-oxide heterojunction (n-ZnO/p-NiO) photoreceptor with a thin tin sulfide layer embedded in between, showing potential for utilization as artificial eyes capable of perceiving various colors. Promisingly, Kamijo et al [3] realized a touchless user interface based on visually transparent NIR-sensitive OPD arrays, which can be used as a penlightcontrolled and gesture-controlled touchless imager on top of a display. The patterned OPD arrays demonstrated transmittance and detectivity up to 70% and 10 12 Jones at 850 nm, respectively.…”

Facile Electret-Based Self-Powered Soft Sensor for Noncontact Positioning and Information Translation

“…In this context, noncontact sensors that can circumvent the above problems are highly desired and have gained increasing interest, showing competitive applications in smart wearable sensing, − information translation, and health monitoring. , To facilitate the development and real-life applications of noncontact sensors, many challenges, including the improvements of the stability and the fabrication process, remain to be addressed. In recent years, extensive efforts have been made regarding these issues. − The main concept for the design and fabrication of noncontact soft sensors is based on electrostatic induction. − Relying on this principle, triboelectric nanogenerators (TENGs) based on triboelectricity have been extensively investigated, providing a powerful approach for the development of self-powered sensors. − As an inspiration for TENGs, scientists have started to extend this self-powered sensing technique to the field of noncontact sensors. For instance, Tang et al used chemical vapor deposition to grow a single layer of graphene on a substrate, resulting in triboelectric touch-free screen sensors that enable gesture recognition without physical contact.…”