An actuator is a device responsible for moving and controlling a machine or system. Typically, actuators require control signals and energy input. The control signal causes the actuator to deform, thereby converting the input energy into mechanical motion, which is used to operate the machine or system. MXenes , a two-atom-thick inorganic compound transition metal carbonitride with polar surface functional groups, has been widely used in many fields such as stimuli-responsive actuators.

Achievements

   Recently, the Korea Advanced Institute of Science and Technology of Il-Kwon Oh professor in the top international journal Advanced Functional Materials published entitled "MXene Printing and Patterned Coating for Device Applications" paper. The comparison of MXenes -based actuators with other two-dimensional material-based actuators is reported , highlighting the main differences in chemical structure, mechanical properties and electrical functions. First, the performance of MXenes is introduced , including cation and ionic liquid intercalation, high capacitance, high electrical conductivity, thermal conductivity, high electromagnetic wave absorption rate, good hydrophilicity and excellent dispersibility in various polar solvents. Secondly, the driving mechanism of electro-ion, electrochemistry, electrothermal, photothermal and humidity-responsive MXenes -based actuators was also thoroughly discussed. Finally, the application of these MXenes -based actuators is summarized and the software robots and future research are mainly discussed.

Figure  1. Various stimuli-responsive MXene -based actuators.

Figure  2 Ion intercalation of  MXene nanosheets.

Figure  3 Ionic liquid intercalation of  MXene nanosheets.

Table 1 Conductivity of materials used for electroactive ion actuators.

Figure  4 Electrothermal performance.

Figure  5 Photothermal performance.

Figure  6 corresponds to humidity.

Table 2 The  advantages of MXene compared to other materials PEDOT: PSS . 

Figure 7 The gap between the MXene nanosheets before and after the response .

Figure 8  MXene is used for stimulus response actuators.

Figure 9  MXene / PEDOT: PSS composite material as an electrode for dry electroactive ion actuators.

Figure 10  Performance of MXene -based electroactive ion actuators.

Table 3  Comparison of MXene -based electroactive ion actuators with other materials.

Figure 11  MXene / cellulose composite material is used as the conductive layer and active layer of the electrothermal actuator.

Figure  12  MXene is applied to wet electric actuators.

Figure  13  MXene is applied to photothermal actuators.

Figure 14  MXene is applied to photothermal actuator 2 .

Figure  15  MXene applied to humidity-responsive actuators.

Figure 16  MXene -based actuators are used in soft robots.

in conclusion

Current synthetic routes including toxic acid treatment and oxidation are a fatal problem for most applications of MXene . Although MXene has been widely used in many fields, it still needs to improve the synthesis process of MXene and improve its stability. The more stable preparation process of MXene material will greatly improve the stability of the actuator, and eventually expand further applications. The analysis of the performance of MXene is also conducive to the choice of actuators for MXene . Choosing the right model and developing the right MXene compound system for the next-generation actuator system are crucial in engineering applications.

Original link:

https://onlinelibrary.wiley.com/doi/full/10.1002/adfm.201909504

Source: MXene Academic