Design of flexible and multifunctional acoustic devices

Abstract

The advent and progression of electronic devices have woven acoustic instruments into the very fabric of daily existence. Instruments like telephones, headphones, and mobile devices have become indispensable in facilitating communication and media consumption. Yet, the architecture of contemporary acoustic apparatuses—principally speakers and microphones—is characterized by an assemblage of cumbersome and inflexible parts. This inherent bulkiness and rigidity curtail the integration of such devices into the emerging spheres of wearables and portable electronics. These constraints beckon a reevaluation of acoustic device design to better align with the evolving demands for flexibility, miniaturization, and seamless integration in personal technology. In order to adapt to the dynamic landscape of user needs, the technological community must endeavor to reimagine acoustic devices. By exploring innovative materials and cutting-edge engineering techniques, it is possible to conceive of acoustic components that not only retain their functional excellence but also offer the much-needed versatility. The pursuit of such advancements would not only augment the portability and wearability of these devices but also significantly broaden the scope of their application, thereby making them more congruent with the lifestyles of a mobile- centric populace. Consequently, the thesis posits that the transformation of acoustic devices from their traditional, rigid frameworks to more adaptable and less obtrusive formats is not only desirable but imperative. This transition is fundamental to not only enhancing user experience but also to unleashing the potential for a new era of technological integration, where acoustic devices can blend unobtrusively with the user's environment and attire, thus embodying the true essence of innovation in the realm of personal electronics. In our research, we explore flexible and multifunctional acoustic devices across several chapters. Chapter 1 delves into recent research trends in flexible loudspeakers and microphones. Chapter 2 presents transparent, flexible, and self-healing thermoacoustic loudspeakers, enhanced with self-healing polymers for increased robustness, making them suitable for wearables, smart windows, and outdoor advertising. Chapter 3 discusses low-voltage, stretchable electroluminescent loudspeakers capable of simultaneous sound and light generation, addressing the issue of high operating voltages in dielectric elastomer actuators through the use of high-k materials. Chapter 4 showcases frequency-selective acoustic and haptic smart skins for dynamic/static human-machine interfaces, addressing the challenges of low sensitivity and accurate frequency sensing in flexible microphones through designs inspired by the human cochlea's basilar membrane. Chapter 5 introduces biomimetic triboelectric acoustic sensors with selective sound detection, emulating the structure of cochlear hair cells for heightened acoustic sensitivity and frequency tuning. Chapter 6 concludes the thesis, summarizing the findings and offering perspectives on future directions for next-generation acoustic devices that combine outstanding performance with compatible designs. This comprehensive study underscores the potential and necessity for innovative acoustic devices in the era of advanced personal electronics.