Abstract
Recent advances in flexible pressure sensors have enabled promising applications in wearable cardiovascular monitoring; however, single-mode sensors often suffer from limitations such as hysteresis, drift, or motion-induced artifacts. In this work, we report a multimodal pressure sensor that integrates supercapacitive and piezoresistive sensing mechanisms into a single vertically stacked device for simultaneous pulse waveform acquisition. The supercapacitive sensor employs a tissue paper-based electrolyte layer, while the piezoresistive sensor utilizes a micropatterned graphene nanoplatelet/multi-walled carbon nanotube (GNP-MWCNT) composite fabricated via a liquid-assisted transfer method. The individual sensors exhibit high sensitivities of 2.85 kPa−1 (capacitive mode) and 19.8 kPa−1 (piezoresistive mode). In the integrated configuration, the multimodal sensor achieves sensitivities of 1 kPa−1 and 2 kPa−1 for capacitive and piezoresistive modes, respectively, and demonstrates stable performance over 5000 loading cycles. The device enables simultaneous detection of pulse waveforms from the same arterial location, capturing key features such as systolic, diastolic, and reflected peaks. The dual-mode sensing approach allows cross-validation of signals, improving measurement reliability compared to single-mode systems. These results demonstrate the potential of the proposed multimodal sensor for continuous and reliable cardiovascular monitoring in wearable healthcare applications.