Transparent loudspeakers let your skin play music

​Seoul: Scientists have developed a transparent, ultrathin device that can turn your skin into a loudspeaker, paving the way for a new generation of wearable sensors and devices. Created in part to help the hearing and speech impaired, the technology can be further explored for various potential applications, such as Internet of Things sensors and conformal health care devices. 

Researchers from Ulsan National Institute of Science and Technology (UNIST) in South Korea developed ultrathin, transparent, and conductive hybrid nanomembranes with nanoscale thickness, consisting of an orthogonal silver nanowire array embedded in a polymer matrix. They, then, demonstrated their nanomembrane by making it into a loudspeaker that can be attached to almost anything to produce sounds.

 The researchers also introduced a similar device, acting as a microphone, which can be connected to smartphones and computers to unlock voice-activated security systems. Nanomembranes (NMs) are molcularly thin seperation layers with nanoscale thickness. Polymer NMs have attracted considerable attention owing to their outstanding advantages, such as extreme flexibility, ultralight weight, and excellent adhesibility in that they can be attached directly to almost any surface. However, they tear easily and exhibit no electrical conductivity. The research team has solved such issues by embedding a silver nanowire network within a polymer-based nanomembrane. This has enabled the demonstration of skin-attachable and imperceptible loudspeaker and microphone.

 "Our ultrathin, transparent, and conductive hybrid NMs facilitate conformal contact with curvilinear and dynamic surfaces without any cracking or rupture," said Saewon Kang, at UNIST. "These layers are capable of detecting sounds and vocal vibrations produced by the triboelectric voltage signals corresponding to sounds, which could be further explored for various potential applications, such as sound input/output devices," Kang said. 

Using the hybrid NMs, the research team fabricated skin-attachable NM loudspeakers and microphones, which would be unobtrusive in appearance because of their excellent transparency and conformal contact capability. These wearable speakers and microphones are paper-thin, yet still capable of conducting sound signals.