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2. Direct imaging of liquid-nanoparticle interface with atom probe tomography

Author

Qiu, Shi., Zheng, Changxi, Zhou, Qi, Dong, Dashen, Shi, Qianqian, Garg, Vivek, Zhang, Shuo, Cheng, Wenlong, Marceau, Ross K. W., Sha, Gang, and Fu, Jing

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics, Physics - Atomic and Molecular Clusters
Abstract

Understanding the structure and chemical composition at the liquid-nanoparticle (NP) interface is crucial for a wide range of physical, chemical and biological processes. In this study, direct imaging of the liquid-NP interface by atom probe tomography (APT) is reported for the first time, which reveals the distributions and the interactions of key atoms and molecules in this critical domain. The APT specimen is prepared by controlled graphene encapsulation of the solution containing nanoparticles on a metal tip, with an end radius in the range of 50 nm to allow field ionization and evaporation. Using Au nanoparticles (AuNPs) in suspension as an example, analysis of the mass spectrum and three-dimensional (3D) chemical maps from APT provides a detailed image of the water-gold interface with near-atomic resolution. At the water-gold interface, the formation of an electrical double layer (EDL) rich in water (H2O) molecules has been observed, which results from the charge from the binding between the trisodium-citrate layer and the AuNP. In the bulk water region, the density of reconstructed H2O has been shown to be consistent, reflecting a highly packed density of H2O molecules after graphene encapsulation. This study is the first demonstration of direct imaging of liquid-NP interface using APT with results providing an atom-by-atom 3D dissection of the liquid-NP interface.

Published
2020
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9. Soft Plasmene Helical Nanostructures.

Author

Shi, Qianqian, Dong, Dashen, Gervinskas, Gediminas, Lin, Han, Sikdar, Debabrata, Jia, Baohua, Walia, Sumeet, Sriram, Sharath, Bhaskaran, Madhu, Yap, Lim Wei, and Cheng, Wenlong

Subjects
*NANOSTRUCTURES, *HELICAL structure, *FOCUSED ion beams, *ENERGY harvesting, *ELASTICITY, *NANOMEDICINE
Abstract

Plasmene is recently defined as 2D arrays of plasmonic nanoparticles, which could be fabricated by the bottom‐up self‐assembly approach and demonstrated a wide range of applications in sensing, energy harvesting, nanophotonics and encryption. Herein, this work further demonstrates a 3D helical plasmonic nanostructures that can be fabricated from 2D plasmene nanosheet. Inspired by chocolate curls‐making process, a micro‐spatula‐based strategy is developed to selectively scrape substrate‐supported plasmene to free space, which spontaneously folds the plasmene nanosheet into various complex helical nanostructures with controlled dimensions. 3D nanospirals can also be obtained by focus ion beam (FIB)‐based lithography on free‐standing plasmene. Helical plasmene structures are robust, exhibiting elastic mechanical properties and chiral optical response. This methodology represents a versatile fabrication route combining both bottom‐up and top‐down approaches to create soft plasmonic helical structures for potential applications in next‐generation flexible nanophotonic devices. [ABSTRACT FROM AUTHOR]

Published
2023
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10. Cell Sheet‐Like Soft Nanoreactor Arrays

Author

Shi, Qianqian, primary, Yong, Zijun, additional, Uddin, Md Hemayet, additional, Fu, Runfang, additional, Sikdar, Debabrata, additional, Yap, Lim Wei, additional, Fan, Bo, additional, Liu, Yiyi, additional, Dong, Dashen, additional, and Cheng, Wenlong, additional

Published
2021
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11. Black Phosphorus—Diketopyrrolopyrrole Polymer Semiconductor Hybrid for Enhanced Charge Transfer and Photodetection

Author

Low, Mei Xian, primary, Kuriakose, Sruthi, additional, Liu, Qian, additional, Taylor, Patrick D., additional, Dong, Dashen, additional, Yang, Terry Chien-Jen, additional, Ahmed, Taimur, additional, Wilson, Gregory, additional, Spencer, Michelle J. S., additional, Tawfik, Sherif Abdulkader, additional, Sriram, Sharath, additional, Bhaskaran, Madhu, additional, Sonar, Prashant, additional, and Walia, Sumeet, additional

Published
2021
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17. 2D Freestanding Janus Gold Nanocrystal Superlattices

Author

Shi, Qianqian, primary, Gómez, Daniel E., additional, Dong, Dashen, additional, Sikdar, Debabrata, additional, Fu, Runfang, additional, Liu, Yiyi, additional, Zhao, Yumeng, additional, Smilgies, Detlef‐M., additional, and Cheng, Wenlong, additional

Published
2019
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20. Covalent-Cross-Linked Plasmene Nanosheets

Author

Liu, Yiyi, primary, Fan, Bo, additional, Shi, Qianqian, additional, Dong, Dashen, additional, Gong, Shu, additional, Zhu, Bowen, additional, Fu, Runfang, additional, Thang, San H., additional, and Cheng, Wenlong, additional

Published
2019
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37. Real-Time and In-Situ Monitoring of H2O2Release from Living Cells by a Stretchable Electrochemical Biosensor Based on Vertically Aligned Gold Nanowires

Author

Lyu, Quanxia, Zhai, Qingfeng, Dyson, Jennifer, Gong, Shu, Zhao, Yunmeng, Ling, Yunzhi, Chandrasekaran, Ramya, Dong, Dashen, and Cheng, Wenlong

Abstract

Traditional electrochemical biosensing electrodes (e.g., gold disk, glassy carbon electrode, etc.) can undergo sophisticated design to detect chemicals/biologicals from cells. However, such electrodes are typically rigid and nonstretchable, rendering it challenging to detect cellular activities in real-time and in situ when cells are in mechanically deformed states. Here, we report a new stretchable electrochemical cell-sensing platform based on vertically aligned gold nanowires embedded in PDMS (v-AuNWs/PDMS). Using H2O2as a model analyte, we show that the v-AuNWs/PDMS electrode can display an excellent sensing performance with a wide linear range, from 40 μM to 15 mM, and a high sensitivity of 250 mA/cm2/M at a potential of −0.3 V. Moreover, living cells can grow directly on our stretchable high-surface area electrodes with strong adhesion, demonstrating their excellent biocompatibility. Further cell stimulation by adding chemicals induced H2O2generation, which can be detected in real-time and in situ using our v-AuNWs/PDMS platform for both natural and stretched states of cells. Our results indicate the v-AuNWs/PDMS electrochemical biosensor may serve as a general cell-sensing platform for living organisms under deformed states.

Published
2019
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39. A General Approach to Free-Standing Nanoassemblies viaAcoustic Levitation Self-Assembly

Author

Shi, Qianqian, Di, Wenli, Dong, Dashen, Yap, Lim Wei, Li, Lin, Zang, Duyang, and Cheng, Wenlong

Abstract

Droplets suspended by acoustic levitation provide genuine substrate-free environments for understanding unconventional fluid dynamics, evaporation kinetics, and chemical reactions by circumventing solid surface and boundary effects. Using a fully levitated air–water interface by acoustic levitation in conjunction with drying-mediated nanoparticle self-assembly, here, we demonstrate a general approach to fabricating free-standing nanoassemblies, which can totally avoid solid surface effects during the entire process. This strategy has no limitation for the sizes or shapes of constituent metallic nanoparticle building blocks and can also be applied to fabricate free-standing bilayered and trilayered nanoassemblies or even three-dimensional hollow nanoassemblies. We believe that our strategy may be further extended to quantum dots, magnetic particles, colloids, etc. Hence, it may lead to a myriad of homogeneous or heterogeneous free-standing nanoassemblies with programmable functionalities.

Published
2019
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40. A location- and sharpness-specific tactile electronic skin based on staircase-like nanowire patchesElectronic supplementary information (ESI) available: Experimental section, supporting figures and videos. See DOI: 10.1039/c8nh00125a

Author

GongThese two authors contribute equally to this work., Shu, Wang, Yan, Yap, Lim Wei, Ling, Yunzhi, Zhao, Yunmeng, Dong, Dashen, Shi, Qianqian, Liu, Yiyi, Uddin, Hemayet, and Cheng, Wenlong

Abstract

Human skin can sense an external object in a location-specific manner, simultaneously recognizing whether it is sharp or blunt. Such tactile capability can be achieved in both natural and stretched states. It is impractical to mimic this tactile function of human skin by designing pixelated sensor arrays across our whole curvilinear human body. Here, we report a new tactile electronic skin sensor based on staircase-like vertically aligned gold nanowires (V-AuNWs). With a back-to-back linear or spiral assembly of two staircase structures into a single sensor, we are able to recognize pressure in a highly location-specific manner for both non-stretched and stretched states (up to 50% strain); with a concentric design on the fingertip, we can identify the sharpness of an external object. We believe that our strategy opens up a new route to highly specific second-skin-like tactile sensors for electronic skin (E-skin) applications.

Published
2018
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41. A Wearable Second Skin‐Like Multifunctional Supercapacitor with Vertical Gold Nanowires and Electrochromic Polyaniline.

Author

An, Tiance, Ling, Yunzhi, Gong, Shu, Zhu, Bowen, Zhao, Yunmeng, Dong, Dashen, Yap, Lim Wei, Wang, Yan, and Cheng, Wenlong

Subjects
NANOWIRES, SUPERCAPACITOR electrodes, SILICON nanowires, GOLD
Abstract

An ideal wearable/implantable bio‐diagnostics can be powered by second skin‐like energy devices in that they offer advantages such as conformal attachment/integration, lightweightness, and moduli‐matching properties. Past several years have witnessed encouraging progresses in soft stretchable supercapacitors by various material combinations and design strategies; however, it remains nontrivial to achieve highly flexible high‐performance supercapacitors in a skin‐thin layout yet with multifunctionality. Here, such a second skin‐like electrochromic supercapacitor is demonstrated using self‐assembled vertical gold nanowires (v‐AuNWs) and electrodeposited polyaniline (PANI). The v‐AuNW film is highly conductive yet offers great flexibility and deformability, while PANI plays a dual role in enhancing capacitance and as charge/discharge‐level indicator. The assembled supercapacitors offer superior skin‐conformability and could achieve an areal specific capacitance of 11.76 mF cm−2 (scan rate of 10 mV s−1) with high durability. A second skin‐like wearable tattoo energy device can be designed with negligible performance deterioration under multiple hand movements and skin deformations. A second skin‐like electrochromic supercapacitor is successfully fabricated using vertically aligned gold nanowires and electrodeposited polyaniline. The nanowire film is highly conductive with outstanding softness and skin‐conformability serving as a current collector, while polyaniline provides pseudocapacitance and serves as a charge/discharge‐level indicator. The supercapacitor exhibits negligible performance deterioration under various skin deformations. [ABSTRACT FROM AUTHOR]

Published
2019
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42. A Moss‐Inspired Electroless Gold‐Coating Strategy Toward Stretchable Fiber Conductors by Dry Spinning.

Author

Zhao, Yunmeng, Dong, Dashen, Gong, Shu, Brassart, Laurence, Wang, Yan, An, Tiance, and Cheng, Wenlong

Subjects
NANOWIRES, ELASTOMERS, ELECTRONICS, TEXTILES, ELECTRICAL conductors
Abstract

Stretchable fiber conductors are appealing in the field of soft electronics due to their potential to be woven into fabrics leading to smart textile electronics. Coating highly conductive metal films onto elastic polymer fibers can be a potential strategy, however, it is nontrivial to achieve strong metal/polymer adhesion to avoid interfacial failure under large mechanical strains. Here, a novel moss‐inspired gold‐coating strategy by using an ultrathin gold nanowires (AuNWs)‐seeded electroless deposition strategy to fabricate stretchable fiber conductors in a dry spinning process is reported. By optimizing Hildebrand's and Hansen's solubility parameter, the AuNWs are dispersed well in an elastomer matrix leading to the efficient scalable production of AuNWs‐impregnated elastomeric fibers. Remarkably, these AuNWs can serve as "seeds" to promote conformal electroless deposition of gold films to substantially enhance the fiber conductivity. Such gold films resemble moss exhibiting strong adhesion to elastomeric polymer fibers because they have AuNWs roots embedded in the polymer matrix. With prestrained fibers, directional cracks along the axis are found, but they can be repaired reversibly when strains are reapplied. This leads to substantial conductivity enhancement. The fiber conductors can be woven into an everyday glove to exhibit superior strain‐insensitivity without changing the intensity of the light‐emitting diode under severe deformations. A moss‐inspired stretchable fiber conductor is fabricated in a dry spinning process together with a following ultrathin gold nanowires (AuNWs)‐seeded electroless deposition process. A seed‐root interfacial design of AuNWs and polymer enables the growth of gold films to enhance conductivity. The conductivity extraordinarily increases with the increase of strain in a large range, exhibiting significant potentials in wearable devices. [ABSTRACT FROM AUTHOR]

Published
2019
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43. Real-Time and In-Situ Monitoring of H 2 O 2 Release from Living Cells by a Stretchable Electrochemical Biosensor Based on Vertically Aligned Gold Nanowires.

Author

Lyu Q, Zhai Q, Dyson J, Gong S, Zhao Y, Ling Y, Chandrasekaran R, Dong D, and Cheng W

Subjects
Breast Neoplasms, Cell Line, Tumor, Electrodes, Female, Humans, Membranes, Artificial, Biosensing Techniques instrumentation, Electrochemical Techniques instrumentation, Gold chemistry, Hydrogen Peroxide metabolism, Nanowires chemistry
Abstract

Traditional electrochemical biosensing electrodes (e.g., gold disk, glassy carbon electrode, etc.) can undergo sophisticated design to detect chemicals/biologicals from cells. However, such electrodes are typically rigid and nonstretchable, rendering it challenging to detect cellular activities in real-time and in situ when cells are in mechanically deformed states. Here, we report a new stretchable electrochemical cell-sensing platform based on vertically aligned gold nanowires embedded in PDMS (v-AuNWs/PDMS). Using H 2 O 2 as a model analyte, we show that the v-AuNWs/PDMS electrode can display an excellent sensing performance with a wide linear range, from 40 μM to 15 mM, and a high sensitivity of 250 mA/cm 2 /M at a potential of -0.3 V. Moreover, living cells can grow directly on our stretchable high-surface area electrodes with strong adhesion, demonstrating their excellent biocompatibility. Further cell stimulation by adding chemicals induced H 2 O 2 generation, which can be detected in real-time and in situ using our v-AuNWs/PDMS platform for both natural and stretched states of cells. Our results indicate the v-AuNWs/PDMS electrochemical biosensor may serve as a general cell-sensing platform for living organisms under deformed states.

Published
2019
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