Kai Lou

A central challenge in three‐dimensional (3D) photoprinting lies in the absence of a deterministic translation from optical fields into volumetric chemical reaction fields. Here, we establish a photoprinting strategy in which light acts not merely as a trigger, but as a programmable input that defines a spatial chemical reaction field enabled by molecular spatial homogeneity and topochemical control. Within this light‐defined reaction field, topochemical reactions are spatially confined and propagated along the depth direction, generating continuous reaction gradients that deterministically translate optical projections into 3D chemical transformations. We realize this concept using a large‐area ADCA‐based single‐cocrystalline photoresist film, in which well‐defined molecular packing supports efficient cascade reactions. The resulting light‐defined spatial reaction field enables low‐power (µW), millimeter‐scale projection photoprinting, producing 3D nanostructures with a sub‐diffraction‐limited lateral resolution of 153 nm and an axial resolution of 3.5 nm. By integrating a home‐built projection system with computational modeling, arbitrary graphic inputs can be directly compiled into programmable 3D chemical reaction fields and rapidly translated into nanoarchitectures within seconds. These results establish topochemical reaction‐field‐guided projection photoprinting as a powerful strategy for rapid, high‐resolution three‐dimensional fabrication in ADCA‐based single‐cocrystalline photoresists and suggest a broader molecular‐design principle for future co‐crystalline photoprinting materials.

A central challenge in three‐dimensional (3D) photoprinting lies in the absence of a deterministic translation from optical fields into volumetric chemical reaction fields. Here, we establish a photoprinting strategy in which light acts not merely as a trigger, but as a programmable input that defines a spatial chemical reaction field enabled by molecular spatial homogeneity and topochemical control. Within this light‐defined reaction field, topochemical reactions are spatially confined and propagated along the depth direction, generating continuous reaction gradients that deterministically translate optical projections into 3D chemical transformations. We realize this concept using a large‐area ADCA‐based single‐cocrystalline photoresist film, in which well‐defined molecular packing supports efficient cascade reactions. The resulting light‐defined spatial reaction field enables low‐power (µW), millimeter‐scale projection photoprinting, producing 3D nanostructures with a sub‐diffraction‐limited lateral resolution of 153 nm and an axial resolution of 3.5 nm. By integrating a home‐built projection system with computational modeling, arbitrary graphic inputs can be directly compiled into programmable 3D chemical reaction fields and rapidly translated into nanoarchitectures within seconds. These results establish topochemical reaction‐field‐guided projection photoprinting as a powerful strategy for rapid, high‐resolution three‐dimensional fabrication in ADCA‐based single‐cocrystalline photoresists and suggest a broader molecular‐design principle for future co‐crystalline photoprinting materials.

Optical tweezers (OT), a cornerstone of micromanipulation, are fundamentally constrained by substrate-induced adhesion and friction, limiting their application to mesoscale objects and fragile biological specimens where overcoming these resistive forces requires physiologically damaging laser powers. Here, we overcome this long-standing challenge by introducing dielectric levitation optical tweezers (DL-OT), a multiphysics platform that seamlessly integrates alternating-current dielectric levitation with optical traps. By using negative dielectrophoresis (n-DEP) to actively neutralize the normal force, DL-OT eliminates solid – solid contact and near-wall viscous drag. Crucially, we demonstrate the fundamental superiority of this active physical levitation over traditional passive antiadhesion coatings. This physical decoupling enables the smooth translation of large biological samples using low, biologically safe optical powers (~15 mW) rather than nonviable levels (>150 mW). The creation of this frictionless environment not only boosts the maximum manipulation speed of standard microtargets by 40% but also enables the stable optical transport of previously intractable mesoscale objects (100 to 260 μm), including microgears and shrimp eggs. By preventing photothermal damage and mechanical deformation, DL-OT demonstrates very good biocompatibility, significantly enhancing cell viability postmanipulation. Building upon these advantages, we demonstrate advanced on-chip biofabrication protocols through the targeted, high-precision assembly of multicellular spheroids and the safe transport of patient-derived organoids, followed by their success in situ culture. By transforming OT from a microscale tool into a mesoscale assembly platform, DL-OT paves the way for breakthroughs in tissue engineering, regenerative medicine, and the bottom – up assembly of living systems.

The precision assembly of anisotropic nanostructures is a prerequisite for next-generation integrated microsystems, quantum photonics, and bio-interfaces. However, bridging the gap between individual manipulation accuracy and scalable, programmable manufacturing remains a grand challenge. Current optical and alternative physical field approaches are hindered by inadequate control stability, thermal damage, and interfacial adhesion limitations. Here, we report a robust hybrid opto-electric microsystem that synergizes alternating current (AC) electric fields with holographic optical tweezers to overcome these barriers. By introducing an Optical Electro-aligning Manipulation (OEM) strategy, we convert the stochastic motion of nanowires into deterministic, pre-aligned trajectories, significantly minimizing scattering forces and optimizing trapping stability. This results in a 38% increase in capture success rate, a 50% reduction in laser power requirements, and a 39% increase in translation speeds for Ag, TiO₂, GaAs, and InAs nanowires. Furthermore, we demonstrate “nano-calligraphy” as a lithography-free patterning technique, enabling the programmable construction of complex micro-patterns with sub-micron resolution. The capability for parallel control of up to seven nanowires and the successful manipulation of biological agents (bacteria) confirm the system’s scalability and versatility. This work establishes a powerful nanomanufacturing platform for the bottom-up assembly of functional NEMS devices, photonic networks, and cellular nanoprobes.

Optical microscopy has been widely used as a versatile tool in biological research. However, its penetration depth and spatial resolution are desperately limited by light scattering during deep propagation in turbid medium. Here, we implement near-infrared second window (1000–1700 nm) multifocal structured illumination microscopy (NIR-II MSIM) capable of deep penetration, high contrast, and enhanced spatial resolution. Raster-scanning multifocal illumination patterns ensure homogeneous illumination of the sample. By integrating NIR-II photoemission into multifocal photoexcitation, NIR-II MSIM affords deep imaging with improved lateral resolution (∼1.49 µm) at a depth of 2.5 mm in an Intralipid/agar phantom and outstanding contrast. Additionally, imaging at longer wavelength in the NIR-II region shows superior performance. This NIR-II MSIM system will afford a promising platform for studying physiological phenomena in turbid specimens in the future.

As a glass-forming liquid is cooled, the dynamics of its constituent particles changes from being liquid-like to more solid-like. The solidity of the resulting glassy material is believed to be due to a cage-formation process, whereby the motion of individual particles is increasingly constrained by neighbouring particles. This process begins at the temperature (or particle density) at which the glass-forming liquid first shows signs of glassy dynamics; however, the details of how the cages form remain unclear^1,2,3,4. Here we study cage formation at the particle level in a two-dimensional colloidal suspension (a glass-forming liquid). We use focused lasers to perturb the suspension at the particle level and monitor the nonlinear dynamic response of the system using video microscopy. All observables that we consider respond non-monotonically as a function of the particle density, peaking at the density at which glassy dynamics is first observed. We identify this maximum response as being due to cage formation, quantified by the appearance of domains in which particles move in a cooperative manner. As the particle density increases further, these local domains become increasingly rigid and dominate the macroscale particle dynamics. This microscale rheological deformation approach demonstrates that cage formation in glass-forming liquids is directly related to the merging of such domains, and reveals the first step in the transformation of liquids to glassy materials^1,5.

The result of molecular diagnostic and detection greatly dependent on the quality and integrity of the isolated nucleic acid. In this work, we developed an automated miniaturized nucleic acid extraction device based on magnetic beads method, consisting of four components including a sample processing disc and its associated rotary power output mechanism, a pipetting module, a magnet module and an external central controller to enable a customizable and automated robust nucleic acid sample preparation. The extracted nucleic acid using 293T cells were verified using real-time polymerase chain reaction (PCR) and the data implies a comparable efficiency to a manual process, with the advantages of performing a flexible, time-saving (~10 min), and simple nucleic acid sample preparation.

Line-temporal focusing has been recognized as an elegant strategy that provides two-photon microscopy with an effective means for fast imaging through parallelization, together with an improved resilience to scattering for deep imaging. However, the axial resolution remains sub-optimal, except when using high NA objectives and a small field-of-view. With the introduction of an intracavity control of the spectral width of the femtosecond laser to adaptively fill the back aperture of the objective lens, line-temporal focusing two-photon microscopy is demonstrated to reach near-diffraction-limited axial resolution with a large back-aperture objective lens, and improved immunity to sample scattering. In addition, a new incoherent flattop beam shaping method is proposed which provides a uniform contrast with little degradation of the axial resolution along the focus line, even deep in the sample. This is demonstrated in large volumetric imaging of mouse lung samples.

We explore how the focusing of axial-symmetry-broken vector fields is associated with a sector aperture whose apex coincides with the field axis. Its focused field is azimuthally split into a pair of orthogonal right- and left-handed circularly polarized partial rings which are rotated by angles of \ifmmode\pm\else\textpm\fi{}$\pi${}/2 with respect to the input vector field carrying no orbital angular momentum (OAM) and no spin angular momentum (SAM), respectively. Each member of the pair of partial rings carries not only the opposite OAM but also the opposite SAM. We unveil the underlying physics behind such an effect.