ABSTRACT
Flexible sensors have attracted extensive attention due to their excellent flexibility, biocompatibility, and information acquisition accuracy. Therefore, it is desired to fabricate a flexible sensor with high toughness and sensitivity based on conductive hydrogels to monitor human movement. In this work, MXene-(Ti3C2Tx-)WPU/PAM dual-network hydrogels (PPM hydrogels) were successfully prepared. As the first network, waterborne polyurethane (WPU) plays the role of energy dissipation and enhancement. Polyacrylamide (PAM) and WPU polymer chains form interpenetrating networks (IPNs). MXene acts as a conductive material to enhance the conductivity and for nano enhancement. The PPM hydrogels exhibited excellent mechanical characteristics (tensile ratio >600%, tensile strength 639 kPa, 1000 stretching cycles, and self-recovery rate 93.7%). Moreover, based on these hydrogels, we fabricated flexible sensors. These sensors had high sensitivity and sensing durability, and could be assembled into a human body wireless monitoring device, which possesses great potential in facial micro-expression monitoring, all-around human motion detection, and wearable electronic products. In addition, these resulting hydrogels possessed outstanding reversible adhesion to various materials (human skin, wood, PDMS, etc.) and the maximum adhesion strength can reach 305.1 N m-1 when exposed to a PDMS substrate. Therefore, PPM hydrogels could provide new inspiration for the development of wearable flexible sensors in the domain of human movements and personalized physiological health monitoring.
Subject(s)
Biocompatible Materials/chemistry , Hydrogels/chemistry , Monitoring, Physiologic , Nanocomposites/chemistry , Polymers/chemistry , Skin/diagnostic imaging , Wearable Electronic Devices , Biocompatible Materials/chemical synthesis , Humans , Hydrogels/chemical synthesis , Molecular Structure , Particle SizeABSTRACT
The advent of electric skins (E-skin) with tactile sensation, flexibility, and human affinity characteristics have attracted considerable attention in extensive research fields, including intelligent robots and health monitoring, etc. To improve the intrinsic brittleness of hydrogels, a multifunctional E-skin was fabricated involving a TEMPO-NFC and a covalently cross-linked polyacrylamide (PAM) network. In this work, silver nanoparticles (AgNPs) as long-term antibacterial agent and conductive fillers were coated onto NFC nanofibers. Subsequently, this nanocomposite hydrogel was synthesized by free radical copolymerization of AM monomers with PNAg fibers as interpenetrating fibers network. Importantly with NFC present, the nanocomposite hydrogel exhibited superior mechanical performance and excellent self-recovery ability. The obtained sensor with excellent mechanical stability and sensing performance could detect mechanotransduction signal of human movements. This work provides a practicable method to prepare high antibacterial efficiency, excellent mechanical performance, and dual-modal nanocellulose-based hydrogel sensor for the broad-range application in human-motion detection and intelligence skins.
Subject(s)
Anti-Bacterial Agents , Biomimetic Materials/chemical synthesis , Biosensing Techniques/instrumentation , Hydrogels , Wearable Electronic Devices , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/therapeutic use , Biomimetic Materials/chemistry , Cellulose/chemistry , Electric Conductivity , Humans , Hydrogels/chemical synthesis , Hydrogels/chemistry , Hydrogels/therapeutic use , Materials Testing , Mechanotransduction, Cellular/physiology , Nanocomposites/chemistry , Nanofibers/chemistry , Silver/chemistry , Skin/chemistry , Skin Physiological Phenomena , Stress, Mechanical , Tensile StrengthABSTRACT
OBJECTIVE: To seek a precise method for estimating postmortem interval (PMI) in forensic medicine practice. METHODS: This study detected the concentration of 21 elements in the vitreous humor of rabbit within 96 hours after death and explored the relationship between their concentration and PMI using the method of ICP-MS. RESULT: It was shown that the concentration of 9 elements in vitreous humor of rabbit within different intervals after death were correlated to PMI available as a reference indicator to estimate PMI. CONCLUSION: The changes in the concentration of certain elements in vitreous humor of vitreous humor are correlated with PMI and determination of such changes can be used to estimate the time of death.
Subject(s)
Magnesium/analysis , Postmortem Changes , Potassium/analysis , Vitreous Body/chemistry , Animals , Calcium/analysis , Forensic Medicine , Iron/analysis , Rabbits , Time FactorsABSTRACT
OBJECTIVE: To seek a exact method of estimating postmortem interval (PMI). METHODS: This study detected the concentration of magnesium (Mg) and iron (Fe) in vitreous humor of rabbit at 96 h after death and explored the relationship between their concentration and PMI using a method ICP-MS. RESULTS: The concentra-tion of Mg in vitreous humor of rabbit at 48 h after death and Fe in vitreous humor of rabbit at 6-48 h after death were related to PMI significantly. The formulae of the relationship between PMI and Mg concentrations is y = 0.0738x2 + 0.6997x + 11.45 (within 48 h, R2 = 0.9119). The formulae of the relationship between PMI and Fe concentrations is y = 0.0411x2 - 0.3148x + 1.4113 (within 6-48 h, R2 = 0.9594). CONCLUSION: The concentration of Mg in vitreous humor of rabbit at 48 h after death and Fe in vitreous humor of rabbit at 6-48 h after death may be as reference indicator to estimate PMI.