"Flexible Age" is coming, flexible wearable sensors are coming in the direction of industrialization

As an important part of flexible mobile phones, flexible wearable sensors are developing from basic research to industrialization. On February 24, local time, Barcelona, ​​Spain, Huawei's foldable smartphone "Mate X" was unveiled at the World Mobile Communications Conference (MWC) at a price of 2,299 euros (about 17,000 yuan). Previously, Rouyu, Samsung, and Xiaomi also showed their collapsible mobile phones.

The "flexible era" has arrived, and the folding screen will be one of the hot spots in the mobile phone market in 2019, which has become the consensus of the industry.

“The general public understands that a foldable mobile phone is a mobile phone with a flexible screen, but this is not the case.” Recently, in an interview, Shen Guozhen, a researcher at the State Key Laboratory of Semiconductor Superlattice, Institute of Semiconductors, Chinese Academy of Sciences, said: “ If you want to realize the folding and bending of the mobile phone at any angle, all the devices on the mobile phone must have this function." As an important part of the flexible mobile phone, the flexible wearable sensor is developing from basic research to industrialization.

Application-driven development

On Shen Guozhen's business card, there is such a line: "Research interests: low-dimensional semiconductor materials and flexible electronic devices." After returning to the US in 2009, Shen Guozhen took flexible electronic devices as his own research direction, and from flexible batteries. At the beginning, he has been involved in many applications in the field of wearable electronics such as flexible transistors and sensors. Among them, flexible wearable sensors for artificial intelligence and health monitoring have always been the focus of their team research, and research results in the fields of flexible tactile sensing, flexible imaging arrays, biosensing, gas sensing and multi-sensor integration have been successively Published in "Advanced Materials", "Chinese Science" and other domestic and foreign academic journals. "Our work in these years is driven by demand, and the corresponding research and development work is carried out according to the application scenarios of flexible sensors." Shen Guozhen concluded.

As one of the authors of a recent paper on flexible and transparent capacitive pressure sensors published in Science in China, Shen Guozhen, a member of the team and an associate researcher at the State Key Laboratory of Semiconductor Superlattice, Institute of Semiconductors, Chinese Academy of Sciences, is working on China. The Science newspaper details the process of developing wearable humidity sensors, data gloves, and many wearable flexible sensors such as piano gloves that will be published. He told reporters that with the continuous advancement of information technology, the demand for developing high-performance flexible sensors is also increasing. It is hoped that the sensor device can be comfortably worn on the body or directly attached to the skin surface, so that a series of health information such as blood pressure, blood sugar, pulse, etc. can be obtained, and the information is collected into the smart device, analyzed and extracted to help the doctor. Make a diagnosis. In addition, by attaching a corresponding flexible sensor and sensing system to a human prosthetic or robot, the perception of the external environment can be realized, and a multi-degree of freedom super-manipulation can be obtained. These make the future of human life more imaginative.

"Because of this, flexible electronics research has been very hot in recent years. Many people have begun to enter this field, which is a good thing, and is crucial for the development and industrialization of the field." Shen Guozhen said. However, he reminded, "In the field of academic research, we should not pursue the heat too much, especially young researchers who have to take root in a certain field, work hard and carry out the necessary research and accumulation."

From sensitivity to transparency

The future development direction of information technology is to achieve the comprehensive and efficient use of the physical world, information data and human social resources through the interaction and integration of human and external information. Based on this goal, they cut through the performance of flexible sensors, gradually improve their sensitivity, stability, and uniformity, and further expand their functions to make them transparent, biocompatible, stretchable, and self-healing. Sex and more performance.

Take, for example, a paper on flexible, transparent capacitive pressure sensors published in China Science recently. In this achievement funded by the Natural Science Foundation, they successfully developed a flexible transparent capacitive pressure sensor based on a special microstructured silver nanowire/PDMS composite dielectric layer material. Compared to dielectric layer devices using pure PDMS planar structures, microstructured sensors offer higher sensitivity, lower detection range, and better stability and durability.

In addition, in the paper, they also discussed the enhanced sensing mechanism of conductive filler content and microstructure, and also developed a 5×5 sensor array for flexible and transparent wearable touch keyboard system. For wearable electronic devices, pressure sensors with high sensitivity and fast response using simple preparation techniques are essential. "Our research results show that pressure sensors have a good application prospect in the future of electronic skin," said Yong Zheng.

In recent years, organic materials and flexible electronic technologies have been organically combined with natural materials as important materials, and various new functional micro-nano structures, devices and integrated systems have been established, which has become one of the important frontier research directions of flexible electronics. In this regard, they collaborated with Wang Lili, an associate professor at Jilin University, to summarize the progress and challenges of the application of plant-based functional materials in green electronic skin, and as a supporting material, active unit and structure from the perspective of the biological properties of plant materials. Prospects for the future development and commercialization of templates are expected. The research results were published last year in Advanced Functional Materials. "In terms of flexible device research, the academic circles at home and abroad are currently mainly in the basic research stage, and there is no obvious gap." Talking about the development of flexible sensors at this stage, Yongzheng told the Journal of Chinese Academy of Sciences. For example, how current flexible sensors simulate human nerves is becoming a frontier, and Chinese scholars have begun to take shape.

Gradually promoted industrialization

Although there is full confidence in the application prospects of flexible wearable sensors, Shen Guozhen and Yongzheng have not rumored the challenges of their industrialization.

"The research results of flexible wearable sensors have a process from laboratory to product." Yong Zheng told the Journal of Chinese Academy of Sciences that the stability and wear resistance of the sensor itself need to be further improved in terms of technology itself. From the perspective of the entire industry chain, flexible circuits, flexible storage, and soft and hard links need to keep up. "In general, if you want to industrialize it on a large scale, the entire industry chain must mature a little more." Shen Guozhen also believes that it is very difficult to turn all devices into flexible devices. However, different scenarios require different flexible technologies, so they can be advanced step by step according to people's needs, for example, the first to achieve flexibility in the pulse sensor.

In this regard, Shen Guozhen is full of expectations for cooperation with enterprises. However, he believes that in view of the current practical problems in the transfer and transformation of China's scientific and technological achievements, Chinese enterprises should start from the long-term development and increase investment in scientific research in the front-end links such as small test and pilot test to ensure that the results enter the mass production stage. And eventually achieve large-scale industrialization.