Noise-resistant wearable piezoelectric nanogenerator for self-powered energy harvesting and real-time speech-to-text conversion in healthcare monitoring

Effective communication in medical and industrial settings is increasingly difficult due to the rise of infectious diseases such as COVID-19, Ebola, and SARS. Protective gear and masks further hinder clear communication for medical personnel. Conventional microphones often fail in these environments due to ambient noise and physical obstructions. To address these challenges, we developed a flexible, self-powered, skin-attachable acoustic piezoelectric nanogenerator (FPENG). The device is fabricated using functionalized multi-walled carbon nanotubes (f-MWCNTs) decorated with barium titanate (BaTiO₃), integrated into an MXene-based hybrid composite within a polydimethylsiloxane (PDMS) matrix. Designed for direct throat attachment, the FPENG detects mechanical vibrations and captures voice signals clearly, even when the mouth is covered or in noisy surroundings. Leveraging the synergistic properties of MXene, f-MWCNTs, and BaTiO₃, it achieves a peak output voltage of ∼1.2 V, outperforming other FPENGs. As an acoustic sensor, it accurately records music and demonstrates high sensitivity to voice frequencies. When attached to the vocal cords, it surpasses commercial microphones in loud environments and with gas masks. Moreover, it enables real-time speech-to-text conversion and cough-type identification, supporting its potential in advanced healthcare monitoring.