Flexible Thin-Film Speaker Integrated with an Array of Quantum-Dot Light-Emitting Diodes for the Interactive Audiovisual Display of Multi-functional Sensor Signals

Abstract

One of the core technologies for wearable electronics is the use of an interactive display device that is attached to the body or clothes to transmit various bio-signals and environmental stimuli to the user. In this study, we report a flexible audiovisual display device consisting of a polyvinylidene difluoride (PVDF) thin-film speaker stacked on an 8 × 8 array of quantumdot light-emitting diodes (QD-LEDs) and a multi-functional sensor consisting of temperature and ultraviolet (UV) sensors connected to a pressure sensor, allowing the body temperature and UV exposure to be displayed both visually and acoustically. Polydimethylsiloxane is employed as an insulator between the carbon nanotube (CNT)/polyaniline temperature sensor and the ZnO/CNT UV sensor to form a capacitor-type pressure sensor. With the use of a stretchable polymer substrate, liquid metal Galinstan interconnections, and the flexible Au-grid electrodes, both the PVDF speaker and the QD-LED array are stable under repeated cycles of bending deformation with a bending radius of 7.5 mm. By connecting the audiovisual display device to the skin-attached multi-functional sensor, changes in the body temperature and UV exposure are displayed as LED patterns with accompanying acoustic alarms. This study demonstrates the significant potential of our proposed audiovisual monitoring device and multi-functional sensor for use in health-monitoring applications, especially for the elderly and infants requiring prompt care.

Flexible and Stretchable Light-Emitting Diodes and Photodetectors for Human-Centric Optoelectronics

“…LEDs, serving as lighting elements, can function as a light source in optoelectronic sensors and emissive pixels in displays. Consequently, by incorporating additional components such as transistor arrays, circuitry components, and sensor units, flexible and stretchable LEDs can be effectively utilized in the development of user-interactive applications. − The deformable feature of these devices contributes to improved wearability and conformability, thereby enhancing user comfort and adaptability to various functions. This section will present notable examples of user-interactive applications utilizing flexible and stretchable LEDs, focusing on display and biomedical applications.…”

Electronic Skin for Health Monitoring Systems: Properties, Functions, and Applications

“…Attaching wearable devices firmly onto the skin or integrating them into portable and daily necessary items to provide monitoring, feedback, and treatment has become a great scientific hotspot. [338][339][340][341] For example, Hua et al developed a self-powered sensor based on an ionic hydrogel to monitor the daily movements of the elderly. [340] The triboelectrical signals generated by the bending fingers corresponded to specific words.…”

Simple fabrication of high-sensitivity capacitive tactile sensor based on a polydimethylsiloxane dielectric layer using a biomimetic gray kangaroo leg structure

“…Researchers and developers are already actively investigating tactile sensors due to their ease of access to acquisition data and applicability to applications. Tactile sensors are mainly classified into four sensing mechanisms: capacitive [16][17][18][19][20], piezoresistive [21][22][23][24], piezoelectric [25][26][27], and triboelectric [28][29][30], among which capacitive tactile sensors with a simplified structure, easy signal acquisition, and low-power consumption have become a research hotspot for researchers [31].…”