In recent years, flexible wearable sensors have attracted much attention for their huge potential in human monitoring, biomedical research, and human-computer interaction. Real-time monitoring and information feedback of human activities (such as blood pressure, pulse and limb movement, etc.) are essential in biomedical research, disease diagnosis and early treatment. So far, wearable functional electronic devices of capacitive, piezoresistive, piezoelectric and triboelectric have been reported. Piezoresistive sensor is a sensor that transforms into resistance change as stress changes. It has the advantages of high sensitivity, fast signal response, low manufacturing cost, and reliable stability. It is considered a strong candidate for the next generation of sensors. Although great progress has been made in the research of piezoresistive sensors, the preparation of low-cost, large-scale preparation and high-sensitivity piezoresistive sensors still faces huge challenges.

【Research results】

Associate Professor Li Luying and Professor Gao Yihua from the Wuhan Optoelectronics National Research Center of Huazhong University of Science and Technology published a research paper titled "Bioinspired Microspines for a High-Performance Spray Ti3C2Tx MXene-Based Piezoresistive Sensor" in the internationally renowned journal ACS Nano. It is reported that a high-sensitivity bionic sensor inspired by human skin has been successfully designed and prepared by a simple sandpaper stencil printing process with a randomly distributed microstructure MXene piezoresistive sensor. The sensor is easy to produce on a large scale, has low cost, high sensitivity, ultra-thin form, can be flexibly attached to the skin, and is expected to be applied to wearable electronic products. It is important that the randomly distributed microstructure can effectively increase the contact area of the conductive channel and improve the performance of the sensor: high sensitivity (151.4 kPa-1), short response time (<130 ms), small pressure detection (4.4 Pa) ), and has excellent stability within 10,000 cycles. Piezoresistive sensors can realize real-time human body monitoring, fine stress detection and pressure distribution quantification, and show great potential in human body monitoring, medical testing, flexible wearables, and human-computer interaction.

[Picture and text quick view]

Figure 1. Design and assembly schematic diagram of a piezoresistive sensor with bionic microstructure.

Figure 2. PDMS characterization of MAX phase, MXene nanosheets, and randomly distributed MXene.

Figure 3. The electromechanical performance of the MXene piezoresistive sensor.

Figure 4. The sensing mechanism of the MXene sensor and the photos of the dynamic process of loading and unloading in FIB-SEM.

Figure 5. Application of MXene piezoresistive sensors in real-time monitoring of human activities and small stress signals.

Figure 6. (a) Photograph of 4×4 array of MXene piezoresistive sensor and detection of corresponding pressure distribution. (B) A photo of the pressure sensor assembled on the robot, and its response to motion behavior is detected. (C) The piezoresistive sensor outputs the current signal to the display screen of the mobile device via Bluetooth.

Literature link: DOI: 10.1021/acsnano.9b08952
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