Integrated wearable sensors with bending/stretching selectivity and extremely enhanced sensitivity derived from agarose-based ionic conductor and its 3D-shaping

Su, Xiaoyang; Borayek, Ramadan; Li, Xinwei; Herng, Tun Seng; Tian, Dan; Lim, Gwendolyn J.H.; Wang, Yanqing; Wu, Jishan; Ding, Jun

doi:10.1016/j.cej.2020.124503

Cited by 21 publications

(8 citation statements)

References 55 publications

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“…We refer the high elasticity to the low-molecular-weight monomers used, which has short chains that can cross-link through hydrogen bonding. 50,51 Indeed, we used the strategy of H-bonding cross-linking to formulate our resins. The investigations of the H-bonding cross-linking have been explained using FTIR results.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Programmable, UV-Printable Dielectric Elastomers Actuate at Low Voltage without Prestretch and Supporting Frames

Borayek

Zhang

Willy

et al. 2020

ACS Appl. Electron. Mater.

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Dielectric elastomers are soft and perfect insulator polymers able to produce large strains with high energy density under the effect of applied high voltage. However, their use in practical applications is hindered by the need for high voltage to actuate. Also, they need prestretching between rigid frames to produce out-of-plane shape changes, which may reduce their lifetime. Here, we synthesized a set of elastomers with high permittivity (from 20 to reach 60 at 10 3 Hz), controllable thermal properties (T g vary from −15 to −50 °C), and good mechanical properties (Young's modulus values between 0.48 and 0.2 MPa at 20% strain). Due to the high permittivity, an actuator made of the material was able to respond to a low voltage of 700 V and produce a 6.5% area strain for more than 10 000 cycles. Moreover, the elastomers were found to produce giant free-end bending displacements with prespecified bending direction (bend to the side of the positive electrode) under a low electric field, which we called programmable dielectric elastomers (PDE). Besides the aforementioned characteristics and performance, the formulated elastomers are suitable for UV-based three-dimensional (3D) printing. The printability of the elastomers allows fabricating programmable complex geometries to produce high deformations under relatively low electric fields.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Programmable, UV-Printable Dielectric Elastomers Actuate at Low Voltage without Prestretch and Supporting Frames

Borayek

Zhang

Willy

et al. 2020

ACS Appl. Electron. Mater.

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“…Moreover, in this work, both P(NIPAM- co -AM) microgel and agarose hydrogel possess good biocompatibility and have been reported as materials in various wearable devices. , Therefore, the agarose@P(NIPAM- co -AM) hydrogel can be deemed as a biosafe wearable sensor.…”

Section: Discussionmentioning

confidence: 99%

Real-Time Personal Fever Alert Monitoring by Wearable Detector Based on Thermoresponsive Hydrogel

Wang

Chen

Zhu

et al. 2021

ACS Appl. Polym. Mater.

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Quick fever screening at a mass scale is proven effective during a pandemic to single out the ones with suspected symptoms of infectious diseases. However, achieving affordable and real-time fever alert at an individual level, although more preferable, remains elusive. Herein, we report an inexpensive and highly sensitive fever detector, which possesses a sharp color transition temperature window tailor-tuned for fever screening. The sensing component of the detector is rationally designed thermoresponsive agarose@poly(N-isopropylacrylamide)-co-acrylamide hydrogel. The hydrogel turns from transparent to opaque white when its temperature is higher than its cloud point. As a proof of concept of its practical applicability, a wearable fever monitoring device was fabricated in the form of a wristband. When the wrist temperature is higher than the threshold of a human fever, the device shows a remarkable color change, alerting an elevated body temperature. The wearable detector provides a promising strategy for real-time fever alert monitoring and is capable of making contributions to inhibit the spread of infectious diseases during a pandemic.

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“…Then, a program of the tensile and cycling tensile loading was applied to the machine and the signals of the change in electrical resistance were captured using a Keithley 2680. For three-point bending, the samples were placed between two rigid holders, and a force was applied from top to bottom using a custom homemade testing setup …”

Section: Characterizationmentioning

confidence: 99%

Near-Zero Hysteresis Ionic Conductive Elastomers with Long-Term Stability for Sensing Applications

Borayek

Foroughi

et al. 2022

ACS Appl. Mater. Interfaces

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Soft conductive elastomers with low hysteresis over a wide range of stretchability are desirable in various applications. Such applications include soft sensors with a long measurement range, motion recognition, and electronic skin, just to name a few. Even though the measurement capability of the sensors based on soft materials has been greatly improved compared to the traditional ones in recent years, hysteresis in the loading and unloading states has limited the applications of these sensors, thereby negatively affecting their accuracy and reliability. In this work, conductive elastomers with near-zero hysteresis have been formulated and fabricated using 3D printing. These elastomers are made by combining highly stretchable dielectric elastomer formulations with a polar hydrophobic ionic liquid and polymerizing under ultraviolet light. High-performance piezoresistive sensors have been fabricated and characterized, with a 10-fold stretchability and low hysteresis (1.2%) over long-term stability (more than 10 000 cycles under cyclic stress) with a 20 ms response time. Additionally, the current elastomers displayed fast mechanical and electrical self-healing properties. Using 3D printing in conjunction with some of our structural innovations, we have fabricated smart gloves to show this material's wide range of applications in soft robots, motion detection, wearable devices, and medical care.

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Integrated wearable sensors with bending/stretching selectivity and extremely enhanced sensitivity derived from agarose-based ionic conductor and its 3D-shaping

Cited by 21 publications

References 55 publications

Programmable, UV-Printable Dielectric Elastomers Actuate at Low Voltage without Prestretch and Supporting Frames

Programmable, UV-Printable Dielectric Elastomers Actuate at Low Voltage without Prestretch and Supporting Frames

Real-Time Personal Fever Alert Monitoring by Wearable Detector Based on Thermoresponsive Hydrogel

Near-Zero Hysteresis Ionic Conductive Elastomers with Long-Term Stability for Sensing Applications

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