Substrate-Free Multilayer Graphene Electronic Skin for Intelligent Diagnosis

Abstract

Current wearable sensors are fabricated with substrates, which limits the comfort, flexibility, stretchability, and induces interface mismatch. In addition, the substrate prevents the evaporation of sweat and is harmful to skin health. In this work, we have enabled the substrate-free laser scribed graphene (SFG) electronic skin (e-skin) with multifunctions. Compared with the eskin with the substrate, the SFG has good gas permeability, low impedance, and flexibility. Only assisted using water, the SFG can be transferred to almost any objects including silicon and human skin and it can even be suspended. Many through-holes like stomas in leaf can be formed in the SFG, which make it breathable. After designing the pattern, the gauge factor (GF) of graphene electronic skin (GES) can be designed as the strain sensor. Physiological signals such as respiration, human motion, and electrocardiogram (ECG) can be detected. Moreover, the suspended SFG detect vibrations with high sensitivity. Due to the substrate-free structure, the impedance between SFG e-skin and the human body decreases greatly. Finally, an ECG detecting system has been designed based on the GES, which can monitor the body condition in real time. To analyze the ECG signals automatically, a convolutional neural network (CNN) was built and trained successfully. This work has high potential in the field of health telemonitoring.

Mass Production of 2D Manifolds of Graphene Oxide by Shear Flow

“…Because the GO mesotubes operate as a sensor in wet conditions, they are highly likely to be used as soft robotics [26][27][28][29] or electronic skin. [30][31][32][33] Recently, flexible, affordable, and elastic wearable electronics have been highlighted for monitoring human biomedical signals. [45,46] The electrical types of wearable sensors can be classified into three groups: chemiresistive, conductometric, and impedimetric.…”

“…The GO mesotubes behaved like a soft gel with a Young's modulus of 974 Pa and were robust to 10 5 cycles of bending tests, rendering them promising candidates as wet sensors for soft robotics [26][27][28][29] and electronic skins. [30][31][32][33] As a proof of concept, we demonstrated that a single GO mesotube can be used as a wet-conditioned sensor for monitoring mechanical vibration and human artery pulse pressure. However, the possible applications of GO mesotubes are not limited to these examples.…”

Recent Progress in Flexible Pressure Sensors Based Electronic Skin

“…The sensor has demonstrated high performance, which was able to detect physiological signals such as respiration, human motion, and electrocardiogram (ECG). [ 56 ] Han et al also designed a flexible pressure sensor based on CB with outstanding performances through an extremely simple and cost‐efficient fabrication process. The pressure sensor demonstrated an ultrahigh sensitivity of 51.23 kPa −1 and an ultralow detection limit of 1 Pa. [ 57 ] In addition; graphene has limitations in its unique use for flexible electronics due to the structural defects, its electrical properties degrade due to mechanical limitations, and the resistance between sheets.…”

Review: Sensors for Biosignal/Health Monitoring in Electronic Skin

“…The sensing layer protects the sensor array and converts tactile information into electrical signals [ 17 , 18 ]. Substrates must have outstanding flexibility and stretchability and be able to withstand conditions of extreme temperature, humidity, deformation, and twisting [ 19 , 20 , 21 , 22 ].…”