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Abstract Direct transfer of pre-patterned device-grade nano-to-microscale materials highly benefits many existing and potential, high performance, heterogeneously integrated functional systems over conventional lithography-based microfabrication. We present, in combined theory and experiment, a self-delamination-driven pattern transfer of a single crystalline silicon thin membrane via well-controlled interfacial design in liquid media. This pattern transfer allows the usage of an intermediate or mediator substrate where both front and back sides of a thin membrane are capable of being integrated with standard lithographical processing, thereby achieving deterministic assembly of the thin membrane into a multi-functional system. Implementations of these capabilities are demonstrated in broad variety of applications ranging from electronics to microelectromechanical systems, wetting and filtration, and metamaterials. 

Abstract It is widely accepted that solid‐state membranes are indispensable media for the graphene process, particularly transfer procedures. But these membranes inevitably bring contaminations and residues to the transferred graphene and consequently compromise the material quality. This study reports a newly observed free‐standing graphene‐water membrane structure, which replaces the conventional solid‐state supporting media with liquid film to sustain the graphene integrity and continuity. Experimental observation, theoretical model, and molecular dynamics simulations consistently indicate that the high surface tension of pure water and its large contact angle with graphene are essential factors for forming such a membrane structure. More interestingly, water surface tension ensures the flatness of graphene layers and renders high transfer quality on many types of target substrates. This report enriches the understanding of the interactions on reduced dimensional material while rendering an alternative approach for scalable layered material processing with ensured quality for advanced manufacturing. 

Abstract Electroretinogram examinations serve as routine clinical procedures in ophthalmology for the diagnosis and management of many ocular diseases. However, the rigid form factor of current corneal sensors produces a mismatch with the soft, curvilinear, and exceptionally sensitive human cornea, which typically requires the use of topical anesthesia and a speculum for pain management and safety. Here we report a design of an all-printed stretchable corneal sensor built on commercially-available disposable soft contact lenses that can intimately and non-invasively interface with the corneal surface of human eyes. The corneal sensor is integrated with soft contact lenses via an electrochemical anchoring mechanism in a seamless manner that ensures its mechanical and chemical reliability. Thus, the resulting device enables the high-fidelity recording of full-field electroretinogram signals in human eyes without the need of topical anesthesia or a speculum. The device, superior to clinical standards in terms of signal quality and comfortability, is expected to address unmet clinical needs in the field of ocular electrodiagnosis. 

Elastocapillary rolling transfer weaves soft materials to spatial structures for programmable robotic applications. 

Abstract Evaporation of droplets composed of insoluble materials provides a low‐cost and facile route for assembling materials and structures in a wide spectrum of functionalities down to the nanoscale and also serves as a basis for innovating ink‐solution‐based future manufacturing technologies. This review summarizes the fundamental mechanics theories of material assembly by droplet drying both on solid and liquid substrates and in a fully suspended air environment. The evolution of assembly patterns, material deformation, and liquid flow during droplet drying and its response to external stimuli ranging from solution surfactant and pH value, surface geometric pattern and wettability, drying temperature, pressure environment, to electrical field have been highlighted to elucidate the coupling mechanisms between solid materials and liquid solutions and the manipulation strategies for material assembly through an either active or passive means. The recent progresses in ink‐based printing technologies with selected examples are also presented to illustrate the immediate applications of droplet drying, with a focus on printing electronic sensors and biomedical devices. The remaining challenges and emerging opportunities are discussed.