Abstract
Graphene-based stretchable and flexible strain sensors are one of the promising “bridges” to the biomedical realm. However, enhancing graphene-based wearable strain sensors to meet the demand of high sensitivity, broad sensing range, and recoverable structure deformation simultaneously is still a great challenge. In this work, through structural design, we fabricated a simple Ecoflex/Overlapping Graphene/Ecoflex (EOGE) strain sensor by encapsulating a graphene sensing element on polymer Ecoflex substrates using a drop-casting method. The EOGE strain sensor can detect stretching with high sensitivity, a maximum gauge factor of 715 with a wide strain range up to 57%, and adequate reliability and stability over 1,000 cycles for stretching. Moreover, the EOGE strain sensor shows recoverable structure deformation, and the sensor has a steady response in the frequency disturbance test. The good property of the strain sensor is attributed to the resistance variation induced by the overlap and crack structure of graphene by structural design. The vibrations caused by sound and various body movements have been thoroughly detected, which exhibited that the EOGE strain sensor is a promising candidate for wearable biomedical electronic applications.
Highlights
In recent years, flexible and stretchable sensors have become one of the most widely studied fields for their potential application in next-generation bioelectronics, including electronic skin, in vitro diagnostics, and human physiological motion detections
Traditional strain sensors based on metals and semiconductors have been well developed, their limited sensing range (
In our previous work, reduced graphene oxide and elastomer were used in the fabrication of wearable strain sensors (Wang et al, 2016; Tao et al, 2017), which displayed relatively large stretchability and high sensitivity properties due to the highdensity cracks
Summary
Flexible and stretchable sensors have become one of the most widely studied fields for their potential application in next-generation bioelectronics, including electronic skin, in vitro diagnostics, and human physiological motion detections The performance of the wearable strain sensors is evaluated by the flexibility, stretchability, sensitivity, and durability (Park S.-J. et al, 2016). It remains a significant demand to develop facile and low-cost techniques to fabricate high-performance graphene strain sensors with a wide detective range. In our previous work, reduced graphene oxide (rGO) and elastomer were used in the fabrication of wearable strain sensors (Wang et al, 2016; Tao et al, 2017), which displayed relatively large stretchability and high sensitivity properties due to the highdensity cracks. Silver paste was used to eliminate the contact resistance by drying under an infrared lamp at 60°C for 12 h Another liquid Ecoflex layer was cast on top of the patterned graphene film to encapsulate the whole structure. The sensor was mounted on the wrist, elbow, knee, neck, cheek, throat, and abdomen to monitor human body motions in real time
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