A Universal high accuracy wearable pulse monitoring system via high sensitivity and large linearity graphene pressure sensor

Highlights: • A new perspective has been proposed theoretically to balance the trade-off between sensitivity and linearity of the piezo-resistive sensor by regulating the conductivity and thickness of the sensing layer. • Strategy to produce high conducting graphene thin film. We presented an all-solution processable, yet simple and environmentally friendly strategy for highly conductive interfacially self-assembled graphene thin sensing film. • Advances in the piezo-resistive pressure sensor. Unprecedented comprehensive properties with both high sensitivity (1875.53 kPa⁻¹) and wide linear detection range (0–40 kPa) pressure sensor were built. • New opportunity for real-time high accuracy pulse monitoring. A high accuracy wearable pulse monitoring system was built and first used to monitor real-time arterial pulse signal during excise. This system holds great potential to be constructed as practically useful physiological real-time monitoring electronic skin in the future. -- Abstract: Long-term accurate pulse monitoring can provide much physiological parameter information in a non-invasive way. A versatile pressure sensor with high sensitivity over a wide linear range (up to 10 kPa) is thus especially desired for this purpose. However, the trade-off between linearity region and sensitivity has not been well balanced. Despite micro/nanostructure morphologies, our simulation and mechanism analyses found that a thinner structure and better conductivity property of the sensing layer contribute to a larger linearity range and higher sensitivity, respectively. However, these two properties are often difficult to achieve simultaneously in one traditional material. Herein, a novel material design strategy is developed to fabricate a self-assembled graphene sensing film, in which the conductivity and thickness can be well balanced. As a result, our sensor exhibits unprecedented comprehensive properties with both high sensitivity (1875.53 kPa⁻¹) and wide linear detection range (0–40 kPa). The sensor is also endowed with good stability and high peak signal-noise ratio (78 dB). Taking advantages of these performances, a universal high accuracy wireless and wearable pulse monitoring system was built. This platform first provides the subtle arterial pulse signal information even under the interference of strong body movement in real-time (during running or cycling), which could not have been realized before. This wearable system is expected to provide more rich and accurate information for personalized diagnostic applications in the future.