Elastocapillary rolling transfer weaves soft materials to spatial structures.

Spatial structures of soft materials have attracted great attention because of emerging applications in wearable electronics, biomedical devices, and soft robotics, but there are no facile technologies available to assemble the soft materials into spatial structures. Here, we report a mechanical transfer route enabled by the rotational motion of curved substrates relative to the soft materials on liquid surface. This transfer can weave soft materials into a broad variety of spatial structures with controllable global weaving chirality and orders and could also produce local ear-like folds with programmable numbers and distributions. We further prove that multiple pieces of soft materials in different forms including wire, ribbon, and large-area film can be woven onto curved substrates with various three-dimensional geometry shapes. Application demonstrations on the woven freestanding spatial structures with on-demand weaving patterns and orders have been conducted to show the temperature-driven multimodal actuating functionalities for programmable robotic postures.

A Nanoconfined Water-Ion Coordination Network for Flexible Energy-Dissipation Devices.

Water-ion interaction in a nanoconfined environment that deeply constrains spatial freedoms of local atomistic motion with unconventional coupling mechanisms beyond that in a free, bulk state is essential to spark designs of a broad spectrum of nanofluidic devices with unique properties and functionalities. Here, it is reported that the interaction between ions and water molecules in a hydrophobic nanopore forms a coordination network with an interaction density that is nearly fourfold that of the bulk counterpart. Such strong interaction facilitates the connectivity of the water-ion network and is uncovered by corroborating the formation of ion clusters and the reduction of particle dynamics. A liquid-nanopore energy-dissipation system is designed and demonstrated in both molecular simulations and experiments that the formed coordination network controls the outflow of confined electrolytes along with a pressure reduction, capable of providing flexible protection for personnel and devices and instrumentations against external mechanical impact and attack.

Electrically Suppressed Outflow of Confined Liquid in Hydrophobic Nanopores.

Confining liquid in a hydrophobic nanoenvironment has enabled a broad spectrum of applications in biomedical sensors, mechanical actuators, and energy storage and converters, where the outflow of confined liquid is spontaneous and fast due to the intrinsic hydrophobic nature of nanopores with extremely low interfacial friction, challenging design capacity and control tolerance of structures and devices. Here, we present a facile approach of suppressing the outflow of water confined in hydrophobic nanopores with an electric field. Extensive molecular dynamics simulations show that the presence of an electric field could significantly strengthen hydrogen bonds and retard degradations of the associated networks during the outflow. The outflow deformation and strength are extracted to quantitatively characterize the electrical suppression to outflow and agree well with simulations. This study proposes a practical means of impeding the fast liquid outflow in hydrophobic nanopores, potentially useful for devising nanofluidics-based functional structures and devices with controllable performance.

Cyclic swelling enabled, electrically conductive 3D porous structures for microfluidic urinalysis devices.

Urinalysis is a simple and non-invasive approach for the diagnosis and monitoring of organ health and also is often used as a facile technique in assessment of substance abuse. However, quantitative urinalysis is predominantly limited to clinical laboratories. Here, we present an electrical sensing based, reusable, cellular microfluidic device that offers a fast urinalysis through quantitative reading of the electrical signals. The spatial soft porous scaffolds decorated with electrically conductive multiwalled carbon nanotubes that are capable of physically interacting with biomarkers in urine are developed through a cyclic swelling/absorption process of soft materials and are utilized to manufacture the cellular microfluidic device. The sensing capability, sensitivity and reusability (via sunlight exposure) of the device to monitor red blood cells, Escherichia coli, and albumin are systemically demonstrated by programming mechanical deformation of porous scaffolds. Ex vivo experiments in disease mouse models confirm the diagnosis robustness of the device in comparable results with existing biochemical tests. The full integration of electrically conductive nanomaterials into soft scaffolds provides a foundation for devising bioelectronic devices with mechanically programmable microfluidic features in a low-cost manner, with broad applications for rapid disease diagnoses through body fluid.

Capillary transfer of soft films.

Existing transfer technologies in the construction of film-based electronics and devices are deeply established in the framework of native solid substrates. Here, we report a capillary approach that enables a fast, robust, and reliable transfer of soft films from liquid in a defect-free manner. This capillary transfer is underpinned by the transfer front of dynamic contact among receiver substrate, liquid, and film, and can be well controlled by a selectable motion direction of receiver substrates at a high speed. We demonstrate in extensive experiments, together with theoretical models and computational analysis, the robust capabilities of the capillary transfer using a versatile set of soft films with a broad material diversity of both film and liquid, surface-wetting properties, and complex geometric patterns of soft films onto various solid substrates in a deterministic manner.

3D Printed Microheater Sensor-Integrated, Drug-Encapsulated Microneedle Patch System for Pain Management.

Microneedle patch devices have been widely utilized for transdermal drug delivery in pain management, but is challenged by accurate control of drug release and subsequent diffusion to human body. The recent emerging wearable electronics that could be integrated with microneedle devices offer a facile approach to address such a challenge. Here a 3D-printed microheater integrated drug-encapsulated microneedle patch system for drug delivery is presented. The ink solution comprised polydimethylsiloxane (PDMS) and multiwalled carbon nanotubes (MWCNTs) with a mass concentration of up to 45% (≈10 times higher of existing ones) is prepared and used to print crack-free stretchable microheaters on substrates with a broad range of materials and geometric curves. The adhesion strength of the printed microheater on the microneedle patch in elevated temperatures is measured to evaluate their integration performance. Assessments of encapsulated drug release into rat's skin are confirmed by examining degradation of microneedles, skin morphologies, and released fluorescent signals. Results and demonstrations established here creates a new opportunity for developing sensor controlled smart microneedle patch systems by integrating with wearable electronics, potentially useful in clinical and biomedical research.