Preparation of flexible pressure sensor based on MXene/PEDOT:PSS and its application in lip language recognition

Lip language is an effective form of verbal communication for patients with vocal cord injuries, laryngeal and tongue injuries, and hearing loss. Lip-speaking signals are generated by lip and facial muscle movements, which contain a large amount of speech information. The extraction and recognition of lip-speaking signals can be achieved by capturing the muscle movements through flexible pressure sensors, providing a more natural and convenient way of accessible communication for patients with listening and speaking dysfunction. In this study, a piezoresistive flexible pressure sensor was prepared using a two-dimensional material, MXene, and a highly conductive polymer, poly(3, 4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), as composites, and a stretchable and microstructured ecoflex as a flexible substrate. The piezoresistive sensor demonstrates a high sensitivity of 42.31 kPa⁻¹ and fast response (<150 ms) in the pressure range of 0-2.5 kPa, and shows high stability in10000 compression-release cycles. The flexible piezoresistive sensor was attached to the corners of the mouth and captured the muscle movements of the lips, which was combined with a convolutional neural network algorithm to train and test the signals of English words in the Chinese zodiac, with an average accuracy of up to 90.18%. This work increases the versatility of lip recognition systems and lays an important foundation for the direct conversion of lip movement signals into speech or text.