Ultrastretchable E‐Skin Based on Conductive Hydrogel Microfibers for Wearable Sensors

Abstract

Conductive microfibers play a significant role in the flexibility, stretchability, and conductivity of electronic skin (e‐skin). Currently, the fabrication of conductive microfibers suffers from either time‐consuming and complex operations or is limited in complex fabrication environments. Thus, it presents a one‐step method to prepare conductive hydrogel microfibers based on microfluidics for the construction of ultrastretchable e‐skin. The microfibers are achieved with conductive MXene cores and hydrogel shells, which are solidified with the covalent cross‐linking between sodium alginate and calcium chloride, and mechanically enhanced by the complexation reaction of poly(vinyl alcohol) and sodium hydroxide. The microfiber conductivities are tailorable by adjusting the flow rate and concentration of core and shell fluids, which is essential to more practical applications in complex scenarios. More importantly, patterned e‐skin based on conductive hydrogel microfibers can be constructed by combining microfluidics with 3D printing technology. Because of the great advantages in mechanical and electrical performance of the microfibers, the achieved e‐skin shows impressive stretching and sensitivity, which also demonstrate attractive application values in motion monitoring and gesture recognition. These characteristics indicate that the ultrastretchable e‐skin based on conductive hydrogel microfibers has great potential for applications in health monitoring, wearable devices, and smart medicine.

Advancements in MXene-based composites for electronic skins

“…MXene-based composites with excellent electrical conductivity, mechanical strength, and flexibility have emerged as promising materials in the field of wearable electronics. 12,18 When MXenes are incorporated into composites, they can enhance the performance and functionality of wearable devices. The addition of MXenes to polymer matrices, such as elastomers or hydrogels, can improve the conductivity and mechanical properties of the resulting composite materials.…”

Challenges and Advances of Hydrogel-Based Wearable Electrochemical Biosensors for Real-Time Monitoring of Biofluids: From Lab to Market. A Review

“…72 Recently, an ultrastretchable e-skin was designed based on conductive hydrogel microfibers for use in wearable sensors. 70 A one-step microfluidic process was utilized for the fabrication of microfibers, which addresses the time-consuming and intricate procedures associated with alternative methods while overcoming limitations in complex fabrication environments. In this process, a mixture of MXene core and a shell solution containing sodium alginate (Na-Alg) and PVA was systematically pumped into a solution containing calcium chloride (CaCl 2 ), sodium hydroxide (NaOH), and water (Figure 3B).…”

“…Recently, an ultrastretchable e-skin was designed based on conductive hydrogel microfibers for use in wearable sensors . A one-step microfluidic process was utilized for the fabrication of microfibers, which addresses the time-consuming and intricate procedures associated with alternative methods while overcoming limitations in complex fabrication environments.…”

Memristor‐Based Bionic Tactile Devices: Opening the Door for Next‐Generation Artificial Intelligence

“…Moreover, e-skin has been widely applied in wearable devices and human-machine interaction due to its advantages such as high photoelectric conversion efficiency and fast response speed. [107,[112][113][114][115][116][117][118][119] For instance, Wang et al designed a flexible e-skin integrating temperature and pressure sensing, which can accurately detect different stimuli for applications in human-machine interfaces, as exhibited in Figure 7a. [107] Guo et al developed a wearable health monitoring device, as shown in Figure 7b, capable of monitoring a variety of sweat components, demonstrating its potential in physiological monitoring.…”