A Hierarchical Contact–Electrification Interface Based on Gradient Micro-/Nanostructured Hydrogel for Cardiovascular Disease Monitoring
Zhenqiu Gao, Liming Zhang, Hao Lei, Yina Liu, Haicheng Gu, Lingjie Xie, Bohan Lu, Haifeng Ji, Zhen Wen, Xuhui Sun
Abstract
Accurate monitoring of pulses is essential for assessing cardiovascular health. However, the specificity of the pulse wave depends on prestress applied to a wearable sensor. Here, we introduce a progressive contact area compensation strategy, which greatly extends the detection range of the sensor's high-sensitivity region. It features a hierarchical flower surface structure and a gradient micro-/nanostructured hydrogel as the dielectric layer, compensating for the output decrease resulting from pressure hardening by gradually increasing the contact area between the contact-electrification interfaces. Consequently, the gradient micro-/nanostructured hydrogel, fabricated via electric field induction, enables the sensor's high-sensitivity region to reach 1.1-52.2 kPa, a 5-fold improvement over that of comparable sensors. By integrating prestress adaptive units, signal processing modules, and a peak seeking algorithm, we develop a wireless wristband for continuous monitoring of cardiovascular status and blood pressure. Importantly, a preliminary 10 day blood pressure test on 22 volunteers showed an error margin of less than ±5 mm Hg, demonstrating its potential as a cardiovascular health product.