Epidermal electronic sensors (EESs) possess great advantages in the real-time and enduring monitoring of human vital information compared to the traditional medical device for intimately making contact with human skin. Skin strain is a significant and effective routine to monitor motion, heart rate, wrist pulse, and skin growth in wound healing. In this paper, a novel skin sensor combined with a ternary conductive nanocomposite (Carbon black (CB)/Decamethylcyclopentasiloxane (D5)/Silbione) and a two-stage serpentine connector is designed and fabricated to monitor skin strain. The ultrasoft (~2 kPa) and adhesive properties of the ternary conductive nanocomposite ensure the capacity of the EES to intimately couple with human skin in order to improve accuracy with a relative error of 3.39% at strain 50% as well as a large strain range (0~50%) and gauge factor (GF ~2.5). The millimeter scale EES (~5 mm × 1 mm × 100 μm), based on the micro-nano fabrication technique, consisted of a two-stage serpentine connector and screen print of the ternary conductive nanocomposite. EESs with high comprehensive performance (electrical and mechanical properties) are fabricated to confirm the analytical results and monitor the motion of a human hand. The good agreement between experimental and analytical results paves the way for bettering monitoring of skin growth during wound healing in order to avoid necrosis and scarring. This EES in monitoring the motion of a human exhibit presents a promising application for assisting prosthetic movement.Keywords:epidermal electronic sensors;skin strain;high accuracy;millimeter scale
Jiaxin Pan,Peng Yu,Hang An,Huabo Huang,Zhou Shu,Yizhou Zhu,Yiming Xiang,Lei Tan
A multifunctional elastomer-organohydrogel hybrid patch for skin surface strain sensors, denoted as MSR-PO, composed of a modified conductive silicone rubber (MSR) and PAA-based organohydrogel (PO), is fabricated by surface radical polymerization of the PO layer on MSR film, the two layers are linked together with the strong chemical bonding, thereby amalgamating their distinct functionalities. The MSR layer endows the patch with great wear-resisting, anti-freezing, and durable sensing properties. The gel layer coated on conductive silicone rubber imparts the patch with excellent adhesive capability to match the modulus of the skin, which is in favor of monitoring large and small movements of the human body, showing great potential in the field of wearable flexible electronic sensing. Importantly, the rubber layer and gel layer of MSR-PO patch exhibit outstanding synergistic antibacterial effects. This work will inspire the design and fabrication of novel rubber-gel asymmetric patch for multifunctional applications.
Wenwu Peng,Xinrong Pan,Xinjuan Liu,Yang Gao,Ting Lu,Jiabao Li,Min Xu,Likun Pan
Ignited by the concept of bionics , hydrogel-based bionic skin sensors have received more and more attention and been widely used in health monitoring, robots, implantable prostheses and human-machine interfaces. However, there still remain some challenges to be urgently solved for hydrogel-based bionic skin sensors, such as the water evaporation and the defects of single conductive mechanism of electronic skin or ionic skin. Herein, we prepared a polyvinyl alcohol/polyacrylamide/CaCl 2 /MXene (PPCM) ionotronics hydrogel with moisture self-regenerative, highly sensitive, ultra-low temperature anti-freezing (−50 °C) and self-adhesive features and applied it as bionic skin strain sensor. The introduction of MXene and CaCl 2 endows the PPCM hydrogel with both electron and ion conductive channels, which effectively compensates for the defects of single electronic skin or ionic skin. Importantly, the addition of CaCl 2 into the PPCM hydrogel offers it the moisture self-regenerative ability, holding the long-term water retention. The water in the PPCM hydrogel can still be kept in a stable state after continuous use for 70 days at room temperature , thus ensuring the long-term stability of the hydrogel-based sensor. Such a moisture self-regenerative ability should be an important feature for intelligentizing the hydrogel-based bionic skin for practical applications.
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