Chronic cranial window (CCW) is an essential tool in enabling longitudinal imaging and manipulation of various brain activities in live animals. However, an active CCW capable of sensing the concealed in vivo environment while simultaneously providing longitudinal optical access to the brain is not currently available. Here we report a disposable ultrasound-sensing CCW (usCCW) featuring an integrated transparent nanophotonic ultrasonic detector fabricated using soft nanoimprint lithography process. We optimize the sensor design and the associated fabrication process to significantly improve detection sensitivity and reliability, which are critical for the intend longitudinal in vivo investigations. Surgically implanting the usCCW on the skull creates a self-contained environment, maintaining optical access while eliminating the need for external ultrasound coupling medium for photoacoustic imaging. Using this usCCW, we demonstrate photoacoustic microscopy of cortical vascular network in live mice over 28 days. This work establishes the foundation for integrating photoacoustic imaging with modern brain research.

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Synergizing grayscale photopolymerization and meniscus coating processes, rapid 3D printing of optical lenses is reported previously using projection microstereolithography (PµSL) process. Despite its 14 000‐fold‐improved printing speed over the femtosecond 3D printing process, PµSL still consumes significant amount of the fabrication time for precise recoating 5 µm thick fresh resin layers. At the reported speed of 24.54 mm3 h−1, 3D printing of the millimeter‐size lenses still takes hours. To further improve the printing speed, the microcontinuous liquid interface production process is implemented to eliminate the time‐consuming resin recoating step. However, the micrometer‐size pores in the Teflon membrane needed for oxygen transportation are found to completely spoil the surface smoothness. The use of polydimethylsiloxane thin film possessing much refined nanoscopic porosities as the functional substitute of Teflon membrane is reported to significantly reduce the surface roughness to 13.7 nm. 3D printing of 3 mm high aspherical lens in ≈2 min at a 200‐fold‐improved speed at 4.85 × 103 mm3 h−1 is demonstrated. The 3D printed aspherical lens has the demonstrated imaging resolution of 3.10 µm. This work represents a significant step in tackling the speed‐accuracy trade‐off of 3D printing process and thus enables rapid fabrication of customized optical components.

In comparison to top-down approaches, nanocomposite thin films are more compatible with nanoparticle (NP) chemistry, device integration, and scalable manufacturing. Nanocomposites have long been promised as an ideal option to fabricate metamaterials that harvest the collective properties enabled by ordered 3D NP assemblies. However, most of accessible NP assemblies, governed by their phase diagrams, are not suitable to achieve the targeted properties and require lengthy assembly processes. Here, we investigated the kinetic pathway of NP assembly in lamellar supramolecular nanocomposite thin films during solvent vapor annealing and after solvent removal. By balancing the solvent field, diffusion rate, and thermodynamic driving force during rapid solvent removal (<3 s), we produced well-ordered 3D NP assemblies far away from the equilibrium state. Their degree of ordering depends on the terminal solvent fraction rather than the exact rapid solvent removal rate. The periodicity of these nanocomposites can be readily decoupled from the NP size and reduced to ∼50% of the periodicity in melt. The current study provides a facile approach to access nonequilibrium structures in nanocomposite thin films for the fabrication of functional metamaterial coatings.

3D printing, formally known as additive manufacturing, creates complex geometries via layer‐by‐layer addition of materials. While 3D printing has been historically perceived as the static addition of build layers, 3D printing is now considered as a dynamic assembly process. In this context, here a new 3D printing process is reported that executes full degree‐of‐freedom (DOF) transformation (translating, rotating, and scaling) of each individual building layer while utilizing continuous fabrication techniques. Transforming individual building layers within the sequential layered manufacturing process enables dynamic transformation of the 3D printed parts on‐the‐fly, eliminating the time‐consuming redesign steps. Preserving the locality of the transformation to each layer further enables the discrete conformal transformation, allowing objects such as vascular scaffolds to be optimally fabricated to properly fit within specific patient anatomy obtained from the magnetic resonance imaging (MRI) measurements. Finally, exploiting the freedom to control the orientation of each individual building layer, multimaterials, multiaxis 3D printing capability are further established for integrating functional modules made of dissimilar materials in 3D printed devices. This final capability is demonstrated through 3D printing a soft pneumatic gripper via heterogenous integration of rigid base and soft actuating limbs.

of numerous components; labor-intensive and costly tasks which often require highly trained personnel and precision alignment equipment.Breaking this cost barrier calls for a cost-effective and scalable manufacturing solution. In contrast to traditional manufacturing processes, additive manufacturing (AM), also referred to as 3D printing, produces complex volumetric structures by the successive addition of building layers. [3] The evolution of AM has seen a rapid growth in satisfying the everincreasing demands in producing geometrically complex parts and assemblies in a wide range of industries, including automobile, [4] aerospace, [5] biomedical, [6] and architecture. [7] This has the potential to transform existing optical manufacturing processes by allowing for design customization directly from digital models without sacrificing manufacturing speed and cost. Its inherent geometric complexity advantages enable a part-count-reduction (PCR) design for producing a single monolithic part to replace existing multicomponent assemblies, reducing lifecycle cost, improving performance, and eliminating further alignment. [8] AM has made great strides over the years to miniaturize optical components. Two-photon direct laser writing with sub-100 nm voxel resolution has demonstrated the fabrication of microlenses and lens assemblies, but at a rather slow "pointby-point" patterning nature. [9] Inkjet printing benefits from the viscosity and surface tension of larger liquid resin droplets to more quickly 3D print optically smooth surfaces on a solid substrate. [10] However, additional molding steps are required for freestanding optical elements. [11] A significant step in tackling this speed/accuracy trade-off was reported by us and other groups by using projection micro-stereolithography (PµSL) and its derivatives. [12] PµSL parallelizes the 3D printing process by curing an entire fabrication layer in a single exposure, being capable of printing millimeter-sized aspherical lenses in 1 h. [12c] Microcontinuous liquid interface production (µCLIP) reported further fabrication speed improvements by eliminating the lengthy resin-recoating step between the printing layers, [13] further reducing fabrication time to minutes. [12a,d] Apart from photopolymer optics, direct ink writing and computed axial lithography have been used to fabricate gradient index and free form optics from silica-based materials, although they require a sintering process utilizing high temperature over 1000 °C. [14] In addition to 3D-printed optical components, filament deposition 3D printers have been used to fabricate the optomechanics This decade has witnessed the tremendous progress in miniaturizing optical imaging systems. Despite the advancements in 3D printing optical lenses at increasingly smaller dimensions, challenges remain in precisely manufacturing the dimensionally compatible optomechanical components and assembling them into a functional imaging system. To tackle this issue, the use of 3D printing to enable digitalized optomechanical...

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Microring resonator (MRR) ultrasound detectors provide orders of magnitude greater sensitivity and frequency range (to < 10 Pa, from DC to 100 s of MHz) than previously achieved in recording acoustic emissions from materials at high pressures. We characterize acoustic emissions from crystal-structural phase transitions in Si to pressures of 50 GPa, well beyond the brittle-ductile transition at room temperature, and find that the number of events increases nearly tenfold for each decade reduction in the duration of recorded events. The shortestduration events arrive in clusters, suggestive of a self-propagating, transformation-catalyzed process.