Authors: Caicong Li, Jianxiang Cheng, YunfengHe, Xiangnan He, Ziyi Xu, Qi Ge & Canhui Yang
Setting: Southern University of Science and Technology
Published in: Nature Communications
In this paper, a series of multi-mode sensing ionized sensors based on polyelectrolyte elastomer were designed and fabricated by using multi-material digital photocuring 3D printing technology, including tensile, compression, shear, torsion and combined sensors. The polyelectrolyte elastomer used is a polymer network containing fixed anions or cations, as well as mobile counterions of the material, with ion leakage resistance. 3D printing technology provides extremely high flexibility for the structural design of the device, and the sensitivity of the sensor can be optimized and regulated through fine structural programming. The prepared sensor has a stable interface and long-term stability, can sense different mechanical stimuli, and there is no signal crosstalk between different sensing paths. This paper provides a new solution for the design, intelligent construction and application of stretchable ionization sensor.
FIG. 1 Schematic diagram of polyelectrolyte elastomer ion electronic sensor with multi-mode sensing capability
Research highlight
Multi-mode sensing: The sensor can sense a variety of mechanical stimuli, including tension, compression, shear and torsion.
Long-term stability: Using polyelectrolyte elastomers and 3D printing technology, the sensor demonstrates excellent long-term stability.
Leak-free design: The new sensor solves the problem that the traditional ion sensor is easy to leak, and improves the reliability of the equipment.
Research background
Ionizer is a kind of device based on the synergistic interaction of ions and electrons, which has the advantages of flexibility, stretchability, optical transparency and biocompatibility, and is widely used in engineering and biomedical fields. Electroionization sensor is an important type of electroionization device, which can sense external mechanical stimuli and convert them into electrical signals for human-computer interaction, intelligent prosthetics, physiological monitoring and other scenarios. However, due to the simple structure and easy leakage of components, the existing ionized sensors have poor stability and single sensing function, which greatly limits the practical application. Therefore, the design and manufacture of electroionization sensors with stable performance and multi-mode sensing capability has important engineering application value.
The problem solved
In order to solve the above problems, this paper uses digital light curing 3D printing technology to manufacture ion capacitors with multi-mode sensing function. The method uses a polyelectrolyte elastomer (PEE), which has high elasticity, high ionic conductivity, high thermal stability, and resistance to ion leakage. Through 3D printing technology, strong interface bonding between PEE and dielectric elastomer (DE) can be achieved, as well as flexible design of device structure. In this paper, we design and manufacture four kinds of basic ion capacitors, which are used to sense different mechanical stimuli such as tension, compression, shear and torsion, and three kinds of combined ion capacitors, which are used to sense various mechanical stimuli and avoid mutual interference of signals. This paper provides a new solution for the design, manufacture and application of stretchable ion capacitors, and also expands the application range of multi-material 3D printing technology.
Research ideas and results are discussed
1. Device preparation and characteristics
This paper uses photocurable precursors of polyelectrolyte elastomers (PEE) and dielectric elastomers (DE) to print ionic electronic sensors. The sensor consists of two PEE layers and an intermediate DE layer. PEE is synthesized by the copolymerization of BS and MBA monomers. Polyelectrolyte elasticity is a kind of material containing fixed anions or cations and mobile counter-ions in the polymer network, which has the characteristics of resisting ion leakage. DE Selected commercial acrylic elastomers. By optimizing the proportion of ionic monomers, the mechanical properties and electrical properties of polyelectrolyte materials are balanced, so as to optimize the performance of the sensor, and the molar ratio of BS and MEA is 1:1.
Since ion-electronic capacitive sensors are multi-layered, it is important to establish a robust interface between the DE and PEE layers to avoid interface delamination. In the 180° peel test, the interface bonding strength of the 3D printed and manually assembled polyelectrolyte elastomer/dielectric elastomer double-layer structures was compared. The 3D printed structure shows stronger interfacial adhesion due to covalent bonds and topological entanglements formed between polyelectrolyte elastomer and dielectric elastomer. The material body is broken during the stripping process, and the bonding strength is as high as 339.3J /m2. On the contrary, due to the weak interface of the manually assembled structure, the interface fracture occurs during the stripping process, and the bonding energy is only 4.1J /m2. Durability tests show that capacitive sensors based on polyelectrolyte elastomers can maintain stable signals for a long time because there is no ion leakage. However, the traditional LiTFSI doped ion elastomer sensor causes signal drift due to ion leakage, which eventually leads to short circuit.
FIG. 2 Preparation process of polyelectrolyte elastomer
Figure 3. Characteristic test of 3D printed ion-electronic capacitance sensor
2. Multi-mode sensing capability
Using multi-material digital light curing 3D printing technology, the author designed and manufactured multi-mode sensor based on polyelectrolyte elastomer, including tensile, compression, shear and torsion sensors. The tensile sensor has good linear response. Under uniaxial tensile action, the area increases, the thickness decreases, and the capacitance increases. Due to the high design and manufacturing flexibility achieved by multi-material 3D printing, the sensitivity of the sensor is significantly improved by constructing the DE layer microstructure, and the sensitivity of the shear and torsion sensor can also be adjusted by changing the shape and overlap area of the front line. 3D printing technology provides extremely high flexibility for the structural design of the device, and the sensitivity of the sensor can be optimized and regulated through fine structural programming. The prepared sensor has a stable interface and long-term stability, can sense different mechanical stimuli, and there is no signal crosstalk between different sensing paths.
Figure 4 Tensile, compression, shear, and torsion sensor performance
Figure 5 Design and performance of integrated ionization sensor
Research summary
In this paper, a series of multi-mode sensing ionized sensors based on polyelectrolyte elastomer were designed and fabricated by using multi-material digital photocuring 3D printing technology, including tensile, compression, shear, torsion and combined sensors. The polyelectrolyte elastomer used is a polymer network containing fixed anions or cations, as well as mobile counterions of the material, with ion leakage resistance. 3D printing technology provides extremely high flexibility for the structural design of the device, and the sensitivity of the sensor can be optimized and regulated through fine structural programming. The prepared sensor has a stable interface and long-term stability, can sense different mechanical stimuli, and there is no signal crosstalk between different sensing paths. The paper also demonstrates a wearable remote control unit consisting of four shear sensors and a compression sensor, and connects it to a remote control system for remotely wirelessly controlling the flight of a drone. This paper provides a new solution for the design, intelligent construction and application of stretchable ionization sensor.
Original source: Polyelectrolyte elastomer-based ionotronic sensors with multi-mode sensing capabilities via multi-material 3D printing. Nat. Commun., 2023, 14, 4853.
https://doi.org/10.1038/s41467-023-40583-5