News Source: School of Physics

Editor: News Agency of BIT

Translator: Yang Ruiguang, News Agency of BIT

Recently, a research group led by Professor Wu Hanchun, Wang Zhi and Jiang Zhaotan of the School of Physics in Beijing Institute of Technology collaborated with Professor Hong Guanming of National Kaohsiung University of Science and Technogy, Professor Zhang Qingrui and Wu Yuren of National Taiwan University, Professor Chen Keqiu of Hunan University, as well as Professor Sunil Arora of University of the Punjab in India, and developed a method to enhance the gauge factor of strain sensors using Van der Waals layered materials, which are at least 500 times more sensible than metallic materials. The interplay of piezoelectric and photoelectric effects not only enhances the gauge factor, but also expands the adjustable range, as well as specifically demonstrates its application in detecting slight vibrations caused by daily movements of human body, making an important contribution to the principle and application of flexible electronics. The innovative research result was published in Nature Communications, a sub journal of Nature, on April 1st.

In recent years, due to the rapid development of soft robots, remote monitoring, artificial intelligence, and wearable health care devices, demand for high-flexibility, high-sensitivity, and low-power strain sensors has surged. At present, most commercially available strain sensors are based on metal materials. However, as metals have no band gap, which limites the GF values of metal strain sensors in a small range of 1 to 5. Although the band gap of conventional semiconducting materials strain is adjustable, these materials are often fragile, restricting their sensing ranges on wearable devices. Compared to metal materials and conventional semiconducting materials, Van der Waals layered semiconducting materials display high elasticity, photoelectric properties and piezoelectric properties, which have great application prospects in energy storage, photoelectricity, sensing, wearable devices and so on. Therefore, the transnational interdisciplinary collaborative team proposed a flexible strain sensor based on Van der Waals layered semiconducting materials. By adjusting the carrier density and mobility via the combined piezoelectric and photoelectric effects, the GF can be tuned over a wide range of values, between 23 and 3933, for the first time. In addition, as shown in the figure below, the Van der Waals flexible sensor is capable of detecting slight vibrations caused by sound and monitoring daily movements of human body, which fully exhibits its potential application prospects in robots, remote monitoring, artificial intelligence, and wearable health care devices.

Figure 1: Van der Waals layered materials strain sensor detecting slight vibrations caused by sound and monitoring daily movements of human body

Yan Wenjie, a 2016 grade Ph.D. student of the School of Physics, is the lead author of the work. Professor Wu Hanchun and Professor Hong Guanming are the corresponding authors. The research project combines band gap calculation, two-dimensional materials and optics and circuit design, which are further verified specifically on flexible electronic wearable devices. The future application of this study is worth looking forward to. This research is supported by the National Natural Science Foundation General Project of China, the National Key Research and Development Program of China, and the Technology Innovation Project of BIT.

Paper information(* represents corresponding author):

Wenjie Yan, Huei-Ru Fuh, Yanhui Lv, Ke-Qiu Chen, Tsung-Yin Tsai, Yuh-Renn Wu, Tung-Ho Shieh, Kuan-Ming Hung*, Juncheng Li, Duan Zhang, Cormac Ó Coileáin, Sunil K. Arora, Zhi Wang, Zhaotan Jiang, Ching-Ray Chang, and Han-Chun Wu*,“Giant Gauge factor of Van der Waals material based strain sensors”, Nature Communications 12, 2018 (2021).

Paper link:

https://www.nature.com/articles/s41467-021-22316-8