An Ultra‐Sensitive Flexible Resistive Sensor with Double Strain Layer and Crack Inspired by the Physical Structure of Human Epidermis: Design, Fabrication, and Cuffless Blood Pressure Monitoring Application

Abstract

The cuffless blood pressure (BP) monitoring device has attracted much attention because of its comfortable and real‐time monitoring. Inspired by the physical structure of the human epidermis, an ultra‐sensitive flexible resistive sensor with a double strain layer and crack structure is prepared by screen printing in this study. The strain material of the sensor is mainly prepared by blending Poly(3,4‐ethylenedioxythiophene) :poly(styrenesulfonate) (PEDOT:PSS) with waterborne polyurethane and reduced graphene oxide. The sensor exhibits a high gauge factor (GF, ≈1682), fast response (≈48 ms), and long‐term stability (> 2000 cycles) at low strain (≈0–5%). The sensor is placed on the human radial artery and can accurately measure the pulse wave. The features of the pulse wave are automatically extracted using a convolutional neural network. Then the features are corrected using a long short‐term memory neural network, and the current BP value is predicted using a fully connected network layer. The BP result meets the A‐level standards of the Association for the Advancement of Medical Instrumentation and the British Hypertension Society. This study provides an efficient device and method for continuous and non‐invasive BP monitoring.

Recent advances in the construction and application of stretchable PEDOT smart electronic membranes

“…Compared to spin coating, spray coating and rod coating, screen printing is suitable for obtaining complex patterns on various substrates. Inspired by the physical structure of the human epidermis, Li et al 184 fabricated a flexible resistive sensor with dual strain layers and a cracked structure by screen printing. Using PEDOT:PSS aqueous solution mixed with waterborne polyurethane (WPU) as ink, the bottom low-conductivity layer was prepared by triple screen printing.…”

Laser-Induced Skin-like Flexible Pressure Sensor for Artificial Intelligence Speech Recognition

“…Therefore, human skin exhibits excellent tactile sensing properties. Inspired by human skin, some skin-like FPS with good sensing performance have been reported. ,− For instance, Li proposed a human epidermis-inspired ultrasensitive pressure sensor with a dual strain layer and crack . Zhao proposed a highly sensitive skin-like pressure sensor for intelligent braille recognition .…”

“…19,27−29 For instance, Li proposed a human epidermisinspired ultrasensitive pressure sensor with a dual strain layer and crack. 30 Zhao proposed a highly sensitive skin-like pressure sensor for intelligent braille recognition. 31 Lei proposed a multifunctional smart skin with ultrahigh sensitivity and efficient fluid actuation through electromechanical-hydraulic coupling.…”

Improving Definition of Screen-Printed Functional Materials for Sensing Application

“…As one of the most used methods for printed electronics, screen printing stands out for its simplicity, scalability, effectivity, and robustness. , This leading technique allows the combination of multiple layers of different materials onto a flexible substrate by transferring the ink through a mesh with a blade/squeegee. By screen printing or by combining this method with other printing methods, different sensing devices can be fabricated, including environmental sensors (temperature, humidity, gas detection), biosensors (glucose, blood pressure), pressure sensors (touch sensors), and light sensors . Many of them are based on a simple structure which consists on a substrate, interdigitated electrodes, and the sensing film. , …”