scispace - formally typeset
Journal ArticleDOI: 10.1039/D0SM01998D

A highly sensitive strain sensor based on a silica@polyaniline core–shell particle reinforced hydrogel with excellent flexibility, stretchability, toughness and conductivity

04 Mar 2021-Soft Matter (The Royal Society of Chemistry)-Vol. 17, Iss: 8, pp 2142-2150
Abstract: Hydrogel-based flexible strain sensors for personal health monitoring and human-machine interaction have attracted wide interest among researchers. In this paper, hydrophobic association and nanocomposite conductive hydrogels were successfully prepared by introducing polyaniline coated silica (SiO2@PANI) core-shell particles into an acrylamide-lauryl methacrylate (P(AM/LMA)) copolymer matrix. The hydrophobic interaction between the SiO2@PANI core-shell particles and the hydrophobic LMA in the P(AM/LMA) chains induced the hydrogels with outstanding mechanical properties. Furthermore, the polyaniline on the SiO2 surface and the inorganic salt formed a conductive network, which synergistically enhanced the conductivity of the hydrogels. The obtained hydrogels integrate high tensile strength (1398 kPa), ultra-stretchability (>1000%), wonderful strain sensitivity (gauge factor = 10.407 at 100-1100% strain), quick response (300 ms), and excellent durability (>300 cycles) due to the hydrophobic association and nanocomposite effect. The prepared SiO2@PANI-P(AM/LMA) hydrogel shows high stress sensitivity to detect human movements and displays a broad application prospect in flexible strain-sensor field.

... read more

Topics: Self-healing hydrogels (59%), Polyaniline (54%), Gauge factor (52%) ... read more
Citations
  More

6 results found



Open accessJournal ArticleDOI: 10.3390/GELS7040164
05 Oct 2021-Gels
Abstract: Conductive hydrogels with stretchable, flexible and wearable properties have made significant contributions in the area of modern electronics. The polyacrylamide/alginate hydrogels are one of the potential emerging materials for application in a diverse range of fields because of their high stretch and toughness. However, most researchers focus on the investigation of their mechanical and swelling behaviors, and the adhesion and effects of the ionic liquids on the conductivities of polyacrylamide/alginate hydrogels are much less explored. Herein, methacrylated lysine and different alkyl chain substituted imidazole-based monomers (IMCx, x = 2, 4, 6 and 8) were introduced to prepare a series of novel pAMAL-IMCx-Ca hydrogels. We systematically investigated their macroscopic and microscopic properties through tensile tests, electrochemical impedance spectra and scanning electron microscopy, as well as Fourier transform infrared spectroscopy, and demonstrated that an alkyl chain length of the IMCx plays an important role in the designing of hydrogel strain sensors. The experiment result shows that the hexyl chains of IMC6 can effectively entangle with LysMA through hydrophobic and electrostatic interactions, which significantly enhance the mechanical strength of the hydrogels. Furthermore, the different strain rates and the durability of the pAMAL-IMC6-Ca hydrogel were investigated and the relative resistance responses remain almost the same in both conditions, making it a potential candidate for wearable strain sensors.

... read more

Topics: Self-healing hydrogels (65%), Alkyl (51%)


Open accessJournal ArticleDOI: 10.1039/D1SM01453F
Fengjin Xie1, Xinpei Gao2, Yang Yu, Fei Lu2  +1 moreInstitutions (2)
16 Nov 2021-Soft Matter
Abstract: Gel electrolytes have aroused extensive interest for diverse flexible electronics due to their high ionic conductivity and inherent stretchability. However, gel electrolytes still face challenges in terms of mechanical properties, fatigue resistance, and environmental adaptation, which severely limit the practical application of gel-based electronics. In this paper, we have synthesized a novel polymerizable ionic liquid [SBMA][AA] by mixing zwitterionic sulfobetaine methacrylate with acrylic acid. Then a dually cross-linked single network poly(ionic liquid)/ionic liquid (DCSN PIL/IL) ionogel was prepared by a simple one-step photopolymerization of the [SBMA][AA] in another IL 1-ethyl-3-methylimidazolium dicyanoamide ([EmIm][DCA]). The synergistic effect between covalent crosslinking and dynamic physical crosslinking points endows the ionogel with good mechanical properties as well as outstanding fatigue resistance. Gratifyingly, the entrapment of [EmIm][DCA] in the ionogel matrix yields excellent environmental adaptability and high ionic conductivity. Meanwhile, the DCSN PIL/IL ionogel also exhibited strong adhesive capacity due to the abundance of carboxyl and sulphonic acid groups. The outstanding electromechanical properties make the DCSN PIL/IL ionogel a perfect candidate for strain sensors to monitor diverse human body activities, such as the movement of the thumb knuckle and handwriting. Interestingly, the DCSN PIL/IL ionogel also displayed high responsiveness to humidity. Therefore, it is believed that this DCSN PIL/IL ionogel offers a broad prospect in flexible strain-humidity bimodal sensors.

... read more

Topics: Ionic liquid (53%)

Journal ArticleDOI: 10.1002/SMLL.202101518
Li Gang1, Chenglong Li1, Guodong Li1, Dehai Yu1  +6 moreInstitutions (3)
17 Oct 2021-Small
Abstract: Conductive hydrogels can be prepared by incorporating various conductive materials into polymeric network hydrogels. In recent years, conductive hydrogels have been developed and applied in the field of strain sensors owing to their unique properties, such as electrical conductivity, mechanical properties, self-healing, and anti-freezing properties. These remarkable properties allow conductive hydrogel-based strain sensors to show excellent performance for identifying external stimuli and detecting human body movement, even at subzero temperatures. This review summarizes the properties of conductive hydrogels and their application in the fabrication of strain sensors working in different modes. Finally, a brief prospectus for the development of conductive hydrogels in the future is provided.

... read more

Topics: Self-healing hydrogels (60%), Body movement (53%)

References
  More

64 results found


Journal ArticleDOI: 10.1038/NNANO.2011.36
Takeo Yamada1, Yuhei Hayamizu1, Yuki Yamamoto1, Yoshiki Yomogida1  +3 moreInstitutions (1)
Abstract: Thin films of single-wall carbon nanotube have been used to create stretchable devices that can be incorporated into clothes and used to detect human motions.

... read more

2,393 Citations


Journal ArticleDOI: 10.1021/ACSNANO.6B05318
Lu Han1, Xiong Lu1, Xiong Lu2, Liu Kezhi1  +10 moreInstitutions (7)
06 Mar 2017-ACS Nano
Abstract: Adhesive hydrogels are attractive biomaterials for various applications, such as electronic skin, wound dressing, and wearable devices. However, fabricating a hydrogel with both adequate adhesiveness and excellent mechanical properties remains a challenge. Inspired by the adhesion mechanism of mussels, we used a two-step process to develop an adhesive and tough polydopamine-clay-polyacrylamide (PDA-clay-PAM) hydrogel. Dopamine was intercalated into clay nanosheets and limitedly oxidized between the layers, resulting in PDA-intercalated clay nanosheets containing free catechol groups. Acrylamide monomers were then added and in situ polymerized to form the hydrogel. Unlike previous single-use adhesive hydrogels, our hydrogel showed repeatable and durable adhesiveness. It adhered directly on human skin without causing an inflammatory response and was easily removed without causing damage. The adhesiveness of this hydrogel was attributed to the presence of enough free catechol groups in the hydrogel, which we...

... read more

Topics: Self-healing hydrogels (63%)

417 Citations


Journal ArticleDOI: 10.1002/ADFM.201703852
Meihong Liao1, Pengbo Wan1, Jiangru Wen1, Min Gong1  +4 moreInstitutions (1)
Abstract: Healable, adhesive, wearable, and soft human-motion sensors for ultrasensitive human–machine interaction and healthcare monitoring are successfully assembled from conductive and human-friendly hybrid hydrogels with reliable self-healing capability and robust self-adhesiveness. The conductive, healable, and self-adhesive hybrid network hydrogels are prepared from the delicate conformal coating of conductive functionalized single-wall carbon nanotube (FSWCNT) networks by dynamic supramolecular cross-linking among FSWCNT, biocompatible polyvinyl alcohol, and polydopamine. They exhibit fast self-healing ability (within 2 s), high self-healing efficiency (99%), and robust adhesiveness, and can be assembled as healable, adhesive, and soft human-motion sensors with tunable conducting channels of pores for ions and framework for electrons for real time and accurate detection of both large-scale and tiny human activities (including bending and relaxing of fingers, walking, chewing, and pulse). Furthermore, the soft human-motion sensors can be enabled to wirelessly monitor the human activities by coupling to a wireless transmitter. Additionally, the in vitro cytotoxicity results suggest that the hydrogels show no cytotoxicity and can facilitate cell attachment and proliferation. Thus, the healable, adhesive, wearable, and soft human-motion sensors have promising potential in various wearable, wireless, and soft electronics for human–machine interfaces, human activity monitoring, personal healthcare diagnosis, and therapy.

... read more

395 Citations


Journal ArticleDOI: 10.1021/ACS.NANOLETT.5B01505
Kyun Kyu Kim1, Sukjoon Hong1, Hyun Min Cho1, Jinhwan Lee1  +3 moreInstitutions (2)
07 Jul 2015-Nano Letters
Abstract: To overcome the limitation of the conventional single axis-strain sensor, we demonstrate a multidimensional strain sensor composed of two layers of prestrained silver nanowire percolation network with decoupled and polarized electrical response in principal and perpendicular directional strain. The information on strain vector is successfully measured up to 35% maximum strain with large gauge factor (>20). The potential of the proposed sensor as a versatile wearable device has been further confirmed.

... read more

Topics: Gauge factor (61%), Stretchable electronics (53%), Percolation (53%)

391 Citations


Journal ArticleDOI: 10.1039/C4NR03295K
Jaehwan Lee1, Sanghyeok Kim1, Jinjae Lee1, Daejong Yang1  +3 moreInstitutions (2)
26 Sep 2014-Nanoscale
Abstract: Wearable strain sensors for human motion detection are being highlighted in various fields such as medical, entertainment and sports industry. In this paper, we propose a new type of stretchable strain sensor that can detect both tensile and compressive strains and can be fabricated by a very simple process. A silver nanoparticle (Ag NP) thin film patterned on the polydimethylsiloxane (PDMS) stamp by a single-step direct transfer process is used as the strain sensing material. The working principle is the change in the electrical resistance caused by the opening/closure of micro-cracks under mechanical deformation. The fabricated stretchable strain sensor shows highly sensitive and durable sensing performances in various tensile/compressive strains, long-term cyclic loading and relaxation tests. We demonstrate the applications of our stretchable strain sensors such as flexible pressure sensors and wearable human motion detection devices with high sensitivity, response speed and mechanical robustness.

... read more

391 Citations