Advances in Research on Biomimetic Graphene Pressure Sensors at Tsinghua University

On January 29th, the team of Ren Tianling from the Department of Microelectronics of Tsinghua University presented the high sensitivity and wide linearity of the random distribution structure of bionic acupuncture at the ACS Nano. The research results of the Epidermis Microstructure Inspired Graphene Pressure Sensor with Random Distributed Spinosum for High Sensitivity and Large Linearity propose a similar biomimetic structure based on the human sensory micro-structures, which is solved through the combination of microstructure and distribution model. The contradiction between the sensitivity and the linear range provides a brand-new idea for the comprehensive improvement of the mechanical device performance.

(Top to bottom, left to right) Schematic representation of the skin's microstructure, photographs of the skin's microstructure and bionic structure, linearity and sensitivity compared to predecessors' performance, wrist pulse and respiratory monitoring results.

In recent years, flexible mechanical micro-nanosensors have become a research hotspot in the field of human physiological information monitoring and detection. At the same time, a large number of related industrial companies have also been established. Compared with traditional silicon-based devices, they are widely used in the monitoring of human physical and chemical activities because of their characteristics of comfort, fit and wearability, but they are two important indicators of mechanical devices: sensitivity and linearity. The contradiction between them has not been well resolved. Generally prepared devices need to sacrifice one index and serve to improve another index, which often limits the scope of its practical application, and solving this contradiction becomes a research difficulty.

Ren Tianling's research group based on the human skin, especially the high sensitivity of fingertips to different sizes of stress response characteristics, according to the study of its microstructure proposed a similar structure. Using a sandpaper as a template to mold the flexible substrate and using graphene oxide as a mechanically sensitive layer after reduction at high temperature, a pressure sensor with acupuncture topography and random distribution was prepared. The sensor exhibits excellent stability, fast response and low detection limit, achieving high sensitivity over a wider linear measurement range. The sudden change of the contact area between the acupuncture structures contributes a high sensitivity, and the random distribution mainly contributes to a wide linear range. The combination of the two resolves this contradiction to a large extent.

Due to the high sensitivity and wide linear range of the sensor, the research team successfully applied to the monitoring of various physiological activities of the human body, such as pulse, respiratory and voice recognition, and also realized the monitoring of walking, running, and jumping walking postures. And monitoring of walking gait. The use of wearable high-performance mechanical sensors for the acquisition of various physical activity parameters of the human body will have important practical significance in personal health and medical care, and has great application prospects.

The research results have been supported by the key projects of the National Natural Science Foundation and the Ministry of Science and Technology.

(Original title: Prof. Ren Tianling of Tsinghua Microelectronics Department of Electronics made important progress in the study of biomimetic graphene pressure sensors)