Shanghai microsystems are making progress in graphene-based wearable fiber sensors

[ Instrument Network Instrument Development ] The sensor is the core component of the IoT terminal device. Wearable stress-strain sensors can be used to collect important signals and human-computer interactions. In addition to the high-sensitivity features required for accurate sensing, practical applications have very high requirements for sensor wear comfort, weight, reliability and stability. Therefore, more sensitive, miniaturized, and integrated is the current development trend of sensors. Integrating the sensor into the traditional fiber and utilizing the advantage of being directly woven to the garment to achieve accurate capture of the local deformation of the human body is an important idea for miniaturization and integration of the wearable sensor device.

Graphene-polymer composite fiber has the advantages of light weight, low signal noise, low energy consumption, etc., and can be used for a resistive strain sensor. For the local micro-deformation of the human body such as heart beat, pulse and blink, the strain is in the range of 0-10%, and the structure and resistance change of the sensor component are required to be deformed, that is, high sensitivity, so as to accurately capture and correct the signal. Accurate analysis of different action states. However, the sensitivity of the graphene-based fiber sensor in the 0-10% strain range is generally low (GF~0.1-50), and how to improve the sensitivity of the graphene fiber sensor in a small strain range is a problem.

In order to solve the above problems, Ding Guqiao, a researcher at the Shanghai Institute of Microsystems and Information Technology of the Chinese Academy of Sciences, proposed a strategy to reduce the contact area between graphene and polymer by structural design to improve sensitivity. They used a graphene/polyvinylidene fluoride/polyurethane DMF system to phase-separate the aqueous phase to prepare a polymer nanosphere-modified graphene porous network fiber, which greatly enhanced the graphene sheet when the fiber was deformed. Structural changes between the layers, resulting in a significant increase in the sensitivity of the graphene-based fibers. The sensitivity factor value is 51 at 0-5% strain and 87 at 5-8% strain. Through braiding integration, they further verify the accuracy of the important signal collection of the fiber in the human body and the feasibility of analysis of different action states. Sex. At the same time, the detection limit of the new graphene fiber sensor has a minimum deformation detection of 0.01%. The better strain-resistance linear relationship can ensure the accuracy of signal post-processing. The cycle life of >6000 cycles is beneficial to the stability of practical applications. .

This fiber is woven into gauze and used as an eye mask to monitor the rotation of the eyeball in real time. It can be used for eye disease monitoring and sleep monitoring in the future. At the same time, the fiber is integrated into the bandage and attached to the wrist to recognize the wrist. The pulse, and the pulse signal can clearly show different signals on the pulse; the fiber can also be programmed into the glove to sense the bending of different hands, indicating that it accurately controls the motion signal. It is precisely because of the existence of the small ball structure that the fiber is given higher sensitivity than the ordinary fiber. The above results meet the requirements of the wearable strain sensor, and the application potential of the graphene-based strain sensor device in the fields of smart medical and wearable devices is embodied. .

The above work was recently published online in the academic journal "Advanced Functional Materials" under the title of Porous Fibers Composed of Polymer Nanoball Decorated Graphene for Wearable and Highly Sensitive Strain Sensor. The first author is Dr. Huang Tao, Ph.D., Shanghai Institute of Microsystems. The authors are Ding Guqiao and He Peng.

Ding Guqiao's research group has long been committed to the innovative preparation and application of graphene materials. The related work has been approved by the National Natural Science Foundation of China, Youth Projects (51802337, 11774368 and 11804353) and Postdoctoral Innovation Talent Support Program (BX201700271) and Shanghai. Strong support from the Municipal Science and Technology Commission project (18511110600).

(Original title: Progress in the graphene-based wearable fiber sensor in Shanghai Microsystems)