Want to play music through your skin? We’re one step closer to this reality thanks to researchers from the USLAN National Institute of Science and Technology (UNIST).
The tech was originally geared toward those with hearing and speech difficulties, however, the researchers note it could also be used in wearable IoT sensor applications.
To achieve this feat, the team developed ultrathin and transparent hybrid nanomembranes (NMs). The conductive material with nanoscale thickness consists “of an orthogonal silver nanowire array embedded in a polymer matrix,” according to the researchers.
In a demonstration, the team was able to hook their NMs to “almost anything to produce sound.” The UNIST researchers went a step further by creating another similar device that acts as a microphone, which can unlock the voice-activated lock systems of smartphones and computers.
“Our ultrathin, transparent, and conductive hybrid NMs facilitate conformal contact with curvilinear and dynamic surfaces without any cracking or rupture,” says Saewon Kang, who’s in the UNIST doctoral program of Energy and Chemical Engineering.
“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 adds.
Polymer NMs, which boast flexibility, lightweight, and adhesibility, face the problem of tearing and the absence of electrical conductivity. However, the team’s embedded silver nanowire network has provided a potential solution with its skin-attachable loudspeaker and microphone abilities.
“The biggest breakthrough of our research is the development of ultrathin, transparent, and conductive hybrid nanomembranes with nanoscale thickness, less than 100 nanometers,” says Professor Hyunhyub Ko in the UNIST School of Energy and Chemical Engineering. “These outstanding optical, electrical, and mechanical properties of nanomembranes enable the demonstration of skin-attachable and imperceptible loudspeaker and microphone.”
Due to the air’s temperature-induced oscillation, the speakers emit a thermoacoustic sound. “The periodic Joule heating that occurs when an electric current passes through a conductor and produces heat leads to these temperature oscillations. It has attracted considerable attention for being a stretchable, transparent, and skin-attachable loudspeaker,” according to UNIST.
Wearable microphones, which act as sensors, can pick up on the vibrations of the user’s vocal chords when attached to the neck. The sensors convert the frictional force from the nanofiber into electrical energy.
“For the operation of the microphone, the hybrid nanomembrane is inserted between elastic films with tiny patterns to precisely detect the sound and the vibration of the vocal cords based on a triboelectric voltage that results from the contact with the elastic films,” according to UNIST.
The full research article, “Transparent and conductive nanomembranes with orthogonal silver nanowire arrays for skin-attachable loudspeakers and microphones,” was published in Science Advances.