We report the discovery of photomolecular effect: cleavage of water clusters off surfaces by photons. This effect is demonstrated through surprising absorption of partially wetted hydrogel in the visible spectrum where both water and hydrogel materials' absorption are negligible. Illumination of hydrogel under solar or visible-spectrum light-emitting-diode leads to evaporation rates exceeding the thermal evaporation limit, even in hydrogels without additional absorbers. Measurements of temperature and transmission spectrum of vapor above evaporating surfaces show clear signatures of water clusters. The photomolecular effect happens at liquid-vapor interface due to large electrical field gradients and quadrupole force on molecular clusters. This photomolecular evaporation process might be happening widely in nature, potentially impacting climate and plants growth, and can be exploited for clean water and drying technologies.

10.48550/arxiv.2201.10385

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IEEE Transactions on Systems, Man, and Cybernetics publication information

IEEE Transactions on Systems Man and Cybernetics Systems (2020)

Eddie Tunstel Sr Past Andreas Nuernberger Sam Kwong Fei‐Yue Wang

10.1109/tsmc.2020.3000410

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Multifunctional “Hydrogel Skins” on Diverse Polymers with Arbitrary Shapes

Advanced Materials (2018)

Yan Yu Hyunwoo Yuk German Alberto Parada You Wu Xinyue Liu

Slippery and hydrophilic surfaces find critical applications in areas as diverse as biomedical devices, microfluidics, antifouling, and underwater robots. Existing methods to achieve such surfaces rely mostly on grafting hydrophilic polymer brushes or coating hydrogel layers, but these methods suffer from several limitations. Grafted polymer brushes are prone to damage and do not provide sufficient mechanical compliance due to their nanometer-scale thickness. Hydrogel coatings are applicable only for relatively simple geometries, precluding their use for the surfaces with complex geometries and features. Here, a new method is proposed to interpenetrate hydrophilic polymers into the surface of diverse polymers with arbitrary shapes to form naturally integrated "hydrogel skins." The hydrogel skins exhibit tissue-like softness (Young's modulus ≈ 30 kPa), have uniform and tunable thickness in the range of 5-25 µm, and can withstand prolonged shearing forces with no measurable damage. The hydrogel skins also provide superior low-friction, antifouling, and ionically conductive surfaces to the polymer substrates without compromising their original mechanical properties and geometry. Applications of the hydrogel skins on inner and outer surfaces of various practical polymer devices including medical tubing, Foley catheters, cardiac pacemaker leads, and soft robots on massive scales are further demonstrated.

Biofouling

Surface forces apparatus

Shearing (physics)

10.1002/adma.201807101

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Citations (379)

Modular Integration of Hydrogel Neural Interfaces

ACS Central Science (2021)

Anthony Tabet Marc‐Joseph Antonini Atharva Sahasrabudhe Jimin Park Dekel Rosenfeld

Thermal drawing has been recently leveraged to yield multifunctional, fiber-based neural probes at near kilometer length scales. Despite its promise, the widespread adoption of this approach has been impeded by (1) material compatibility requirements and (2) labor-intensive interfacing of functional features to external hardware. Furthermore, in multifunctional fibers, significant volume is occupied by passive polymer cladding that so far has only served structural or electrical insulation purposes. In this article, we report a rapid, robust, and modular approach to creating multifunctional fiber-based neural interfaces using a solvent evaporation or entrapment-driven (SEED) integration process. This process brings together electrical, optical, and microfluidic modalities all encased within a copolymer comprised of water-soluble poly(ethylene glycol) tethered to water-insoluble poly(urethane) (PU-PEG). We employ these devices for simultaneous optogenetics and electrophysiology and demonstrate that multifunctional neural probes can be used to deliver cellular cargo with high viability. Upon exposure to water, PU-PEG cladding spontaneously forms a hydrogel, which in addition to enabling integration of modalities, can harbor small molecules and nanomaterials that can be released into local tissue following implantation. We also synthesized a custom nanodroplet forming block polymer and demonstrated that embedding such materials within the hydrogel cladding of our probes enables delivery of hydrophobic small molecules in vitro and in vivo. Our approach widens the chemical toolbox and expands the capabilities of multifunctional neural interfaces.

Interfacing

Cladding (metalworking)

Neural tissue engineering

10.1021/acscentsci.1c00592

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Bioadhesive Technology Platforms

Chemical Reviews (2023)

Sarah J. Wu Xuanhe Zhao

Bioadhesives have emerged as transformative and versatile tools in healthcare, offering the ability to attach tissues with ease and minimal damage. These materials present numerous opportunities for tissue repair and biomedical device integration, creating a broad landscape of applications that have captivated clinical and scientific interest alike. However, fully unlocking their potential requires multifaceted design strategies involving optimal adhesion, suitable biological interactions, and efficient signal communication. In this Review, we delve into these pivotal aspects of bioadhesive design, highlight the latest advances in their biomedical applications, and identify potential opportunities that lie ahead for bioadhesives as multifunctional technology platforms.

Transformative Learning

10.1021/acs.chemrev.3c00380

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Citations (54)

IEEE Transactions on Systems, Man, and Cybernetics publication information

IEEE Transactions on Systems Man and Cybernetics Systems (2023)

Sam Kwong Sr Past Eddie Past Yo-Ping Huang Enrique Herrera‐Viedma

10.1109/tsmc.2023.3235528

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Ultrasound-responsive hydrogel microcapsules for on-demand drug release

The Journal of the Acoustical Society of America (2023)

Rachel D. Field Margaret A. Jakus Xiaoyu Chen Kelia Human Xuanhe Zhao

Hydrogel-based implantable systems offer viable solutions for localized drug delivery but often lack the ability to easily achieve on-demand actuation or real-time tuning of release kinetics in response to physiological changes. Here, we present a hydrogel microcapsules produced using two-phase microfluidics that can release drugs on demand as triggered by focused ultrasound (FUS). The biphasic microcapsules consist of an outer phase of mixed molecular weight (MW) poly(ethylene glycol) diacrylate that mitigates premature payload release and an inner phase of high MW dextran with payload that breaks down in response to FUS. Compound release from microcapsules could be triggered as desired; 0.4 μg of payload was released across 16 on-demand steps over days. We detected broadband acoustic signals amidst low heating, suggesting inertial cavitation as a key mechanism for payload release. Overall, FUS-responsive microcapsules are a biocompatible and wirelessly triggerable structure for on-demand drug delivery over days to weeks.

Payload (computing)

On demand

10.1121/10.0023522

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Harnessing large deformation and instabilities of soft dielectrics: Theory, experiment, and application

Applied Physics Reviews (2014)

Xuanhe Zhao Qiming Wang

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Xuanhe Zhao, Qiming Wang; Harnessing large deformation and instabilities of soft dielectrics: Theory, experiment, and application. Appl. Phys. Rev. 1 June 2014; 1 (2): 021304. https://doi.org/10.1063/1.4871696 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioApplied Physics Reviews Search Advanced Search |Citation Search

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10.1063/1.4871696

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Citations (161)