Biocompatible MXene/Chitosan-Based Flexible Bimodal Devices for Real-Time Pulse and Respiratory Rate Monitoring

Abstract

Electronic skins, often with recognition and sensing capabilities that are beyond those associated with biological skin, provide important medical information for human health. However, how to make electronic skins with both tactile and touchless perceptions for applications in real-time health monitoring is a challenge due to biological complexity. Herein, flexible bimodal e-skins are demonstrated using a lamellated MXene/chitosan film as the kernel sensing layer. These biomimetic hybrid films show excellent biocompatibility in a cytotoxicity test, indicating a reduced risk of application in the human body. The flexible devices display two modes that can detect pressure (with a limit of detection (LoD) of 3 Pa, stability >3500 times, and response time of 143 ms) and humidity (stability >20 days). The bifunctional sensor can also be used in detecting and discriminating electrophysiological signals (including voice recognition, human pulses, and finger bending) and biochemical molecules (respiratory rate). This work may lead to the application of biocomposite materials in multifunctional flexible sensing technology.

High-Performance Flexible Capacitive Proximity and Pressure Sensors with Spiral Electrodes for Continuous Human–Machine Interaction

“…The dielectric layer is the main factor affecting the performance of capacitive devices; other demands are good flexibility and transparency. − Calcium cross-linked alginate (CCA), a natural and inexpensive polysaccharide, has received increasing attention as a biomaterial with good mechanical properties, biocompatibility, and biodegradability. − However, the fast cross-linking reaction between sodium alginate (SA) and calcium ions brings difficulty in producing CCA films with ultrathin, homogeneous, transparent, and microstructured surfaces, which has limited their application in electronic devices so far. − In general, applications based on the structure-related functional capacitive device allow for improving strategies through the combination of electrode pattern designs and microstructured electronic material development.…”

Electrochemical Detection of Femtomolar DNA via Boronate Affinity-Mediated Decoration of Polysaccharides with Electroactive Tags

“…As an important class of biological polymers, polysaccharides are renewable long-chain polymers composed of tens to thousands of monosaccharide units linked together by glycosidic bonds. Due to their excellent biodegradability and biocompatibility, polysaccharides (e.g., chitosan, alginic acid, pectin, and their derivatives) have attracted much research interest in a variety of fields, such as in drug delivery as carriers, , in implantable devices , and flexible electronic devices , as coating materials to improve the biocompatibility, and in biosensing as interface modification materials for the covalent immobilization of biological molecules, like DNAs, , enzymes, , and antibodies. , As the pendent functional groups (e.g., −NH 2 and −COOH) of the monosaccharide units are available for the covalent coupling, polysaccharides have also been used as mediators for the decoration of signal tags for amplified detection . Through dual amplification by alginic acid and glucose oxidase (GOx), for example, an electrochemiluminescence (ECL) method has been demonstrated by Zhang et al for amplified cytosensing and carbohydrate profiling because each alginic acid chain can be covalently decorated with multiple GOx.…”

Applications of MXenes in human-like sensors and actuators

“…First, MXenes become emerging conductive materials [209] compared to indium tin oxide, metals, and graphene. Second, the MXene can incorporate into the polymeric composite [168,[210][211][212][213][214][215] as an active layer for improving the sensitivity. Moreover, the active layer may employ the macrostructures, such as interlocking [216], hollow spheres [217], porous [218], and lamellar architectures [219].…”