Wearable Heart Rate Sensor Based on Mxene-Coated Polymer Membrane

The development of flexible and wearable sensors for heart rate monitoring has gained significant attention due to the increasing demand for real-time, non-invasive, and continuous cardiovascular health assessment, particularly in sports medicine, athletic performance tracking, and personalized healthcare. Among various candidate materials, polyvinylidene fluoride (PVDF) has emerged as a promising substrate due to its exceptional mechanical flexibility, lightweight nature, chemical stability, and ease of integration into wearable devices. This study introduces an innovative approach by coating PVDF membranes with MXene layers, which act as an electrically conductive channel, facilitating accurate detection of heart rate signals when used in piezoresistive mode, provided the conductive MXene layer was optimized to an appropriate thickness. Structural characterization via XRD, SEM, and SEM-EDX confirmed the successful formation of stable, layered MXene structures without signs of oxidation. Heart rate monitoring tests performed with a MXene-PVDF sensor on a pulse simulator and analyzed with the HeartPy software revealed superior sensor performance, characterized by a high signal-to-noise ratio (SNR~26.78 dB) and excellent accuracy in tracking the preset beats per minute (BPM). The results of heart rate sensing experiments demonstrated that sensors with a thin MXene conductive layer exhibit excellent sensitivity, while those featuring a thicker MXene layer displayed a lack of responsiveness. The obtained results highlight the great potential of MXene-coated polymer sensors for advanced wearable health monitoring applications, particularly in professional sports performance assessment and personalized medical diagnostics.