With the vigorous development of the Internet of Things, wearable sensors, as an important part of human-machine interfaces (HMIs), have attracted great attention in many applications such as human health and sports monitoring. The development of integrated human-machine interface systems requires sensors with good wear resistance, sensitivity, flexibility and comfort. Pressure sensors can meet the requirements of wearable HMIs. However, it is important to choose a simple, reliable, and suitable pressure-sensitive mechanism for fabric materials. There are generally four types of pressure sensing mechanisms, including piezoresistive, piezoelectric, capacitive and triboelectric. Piezoresistive sensors have the characteristics of simple structure, wide detection range and high sensitivity, and are suitable for wearable HMIs. In addition, by loading the active material directly on the fabric, a flexible piezoresistive sensor can be easily manufactured. However, for piezoresistive sensors used in HMIs, there are still some problems to be solved.

Recently, Associate Researcher Hou Chengyi of Donghua University published a research paper titled: MXene-Coated Air-Permeable Pressure-Sensing Fabric for Smart Wear in the internationally renowned academic journal ACS Applied Materials & Interfaces. In this work, Ti3C2Tx MXene nanosheets were coated on 15 different fabrics to clarify the interaction mechanism between the fabric and MXene nanosheets. Choose pure cotton as the most promising flexible substrate. It is worth noting that a strong bond is formed between Ti3C2Tx and pure cotton, which can prevent the active material from detaching even under the action of ultrasonic waves in the water. Therefore, we applied MXene coated cotton fabric with good cleaning durability and permeability (972.2 MMS-1) to the wearable flexible pressure sensor, which showed high sensitivity (7.67 kPa-1), fast response and relaxation Speed (35 ms), good stability (2000 cycles) and wide sensing range (35%). In addition, this article will also connect the prepared pressure sensor to a music player on a personal computer (PC) to further demonstrate its practical applicability as an HMI sensor. This nano-coated cotton pressure-sensitive fabric provides a new way to manufacture low-cost wearable pressure sensors.

Figure 1. The adsorption performance of MXene on different fabrics.

Figure 2. Performance characterization of MXene coated cotton fabric.

Figure 3. Analysis of MXene before and after surface modification of cotton fabric.

Figure 4. Pressure sensitive performance of MXene coated cotton pressure sensitive fabric.

Figure 5. The proof of concept of the MXene coated cotton HMI system.

     In summary, this paper uses the interwoven cotton fabric and MXene as the substrate and active material to assemble a flexible and wearable pressure sensor. Due to the natural rough surface of cotton fiber and the three-dimensional warp and weft structure of woven fabric, cotton fabric is more conducive to the physical adsorption of MXene than other fabrics. In addition, MXene coated cotton maintains good air permeability (972.2 MMS-1) and moisture permeability (227.92 g m-2). When used as a pressure sensor, MXene coated cotton pressure-sensitive fabric shows high sensitivity (GF = 7.67 kPa-1), rapid response and recovery speed (<35 ms), and excellent stability (>2000 cycles). In addition, the successful application of the sensor in controlling music player software shows the important prospects of this device in human-machine interface systems. The device has a simple manufacturing process, high efficiency and low cost. In addition, the entire process is scalable and does not require complex and expensive equipment. The method in this article provides a new way for low-cost pressure sensors, which can be easily integrated into future wearable electronic products.

Literature link:

https://doi.org/10.1021/acsami.0c11715.

Information source: MXene Frontie

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