The structures were fabricated by direct laser writing in a pre-polymer, a process in which a focused laser triggers a localized chemical reaction in a photosensitive material. The laser defines a desired pattern within the precursor, but the pattern does not necessarily become visible as a free-standing object until development removes the unpolymerized material. That step can distort, break or hide delicate features, and it also means that defects or positioning errors may be discovered only after the sample has been processed. A method for seeing the written pattern before development could therefore shorten the feedback loop between fabrication and quality control.

Photoluminescence mapping works by measuring the light emitted from the material after it is illuminated. In the system investigated by the authors, the photo-initiator provides the signal of interest. The initiator is present in the precursor, but its emission is quenched in polymerized regions, where it has been consumed or incorporated into the newly formed polymer network. The contrast between emitting and non-emitting regions reveals where the laser has written. Because the measurement is performed in three dimensions, the mapped signal can establish the location of the features in all three spatial directions rather than only on an exposed surface.

The researchers tested this approach in both open configurations and fully three-dimensional, closed microfluidic channels. That distinction matters because a closed channel hides the internal structure from direct optical inspection, while an open system provides more immediate access to the written material. The experiments also extended photoluminescence mapping to fused-silica microfluidic platforms, where the geometry and material properties of the device can make conventional characterization difficult. In both settings, the method was able to identify polymerized features before development.

One of the most useful findings is that the method can be applied repeatedly during fabrication without damaging the structures. This makes the optical signal more than a one-time inspection. During a multi-step writing process, researchers could map the developing geometry, check the placement of features and identify whether a subsequent laser exposure is aligned with the intended architecture. The ability to inspect the sample in place is especially valuable when a structure must be registered to channels, walls or other components that are already part of the device.

The measurements also revealed a consistent difference between the apparent photoluminescent footprint and the final developed structure. The signal detected by the mapping system was smaller than the structure that emerged after development. This is not simply a limitation to be ignored: it indicates that the optical contrast is associated with the polymerized region before the surrounding precursor is washed away, and that the apparent size changes as the material develops. Researchers using the technique must therefore interpret the map in relation to the final fabrication process rather than treating the initial signal as a literal outline of the finished object.

That distinction is especially important for quality assessment. A weak or irregular photoluminescence pattern can reveal that a laser-written region differs from its intended form, even when the difference is not yet visible to the eye. The technique can expose local errors, misplaced features and incomplete writes while correction is still possible. Its value lies in providing spatially resolved feedback: instead of learning that a completed device is defective, a researcher may discover the problem during the writing sequence and adjust the next exposure or the alignment of the fabrication system.

The approach also offers a way to connect an optical signal with a three-dimensional fabrication process. A conventional two-dimensional image may show that a feature exists at a particular position on a surface, but it cannot necessarily reveal its depth or orientation inside a transparent channel. The photoluminescence maps used in this study provide three-dimensional localization, allowing the researchers to determine where the written structures lie before the sample is developed. That could support more reproducible placement of internal components and improve the yield of devices containing complex three-dimensional geometry.

The work does not mean that photoluminescence mapping replaces every conventional characterization method. The researchers present it as a practical in situ tool, and its interpretation depends on the chemistry of the precursor, the behavior of the photo-initiator and the way the structure is developed. Its principal advantage is that it works before development, when the object is still embedded and when a failure could be difficult or impossible to see by ordinary means. The authors also report that the method extends the applicability of photoluminescence mapping to fused-silica microfluidic platforms, broadening its potential reach beyond earlier applications.

For microfabrication, the most immediate impact may be a faster and more transparent workflow. A laboratory can write a device, pause to map the internal polymer network and check its placement, then continue with additional processing. The same principle could support automated alignment, process monitoring and repeated assessment of complex geometries. The signal is not merely a way to visualize a finished specimen; it is a process-control tool that brings information about the hidden structure into the fabrication environment itself. As microfluidic devices become more intricate and more sensitive to small errors, methods that reveal internal features before they become permanent could become valuable building blocks for more dependable manufacturing.

Subject of Research: In situ photoluminescence mapping of laser-written three-dimensional polymeric microstructures in microfluidic channels

Article Title: In situ evaluation of 3D polymeric microstructures integrated into a microfluidic channel

Article References: Rekštytė Paipulienė, S., Paipulas, D., & Mizeikis, V. (2026). In situ evaluation of 3D polymeric microstructures integrated into a microfluidic channel. Scientific Reports. https://doi.org/10.1038/s41598-026-75388-1

Image Credits: AI Generated

DOI: 10.1038/s41598-026-75388-1

Keywords: microfluidics, photoluminescence mapping, direct laser writing, polymer microstructures, microfabrication, photoinitiators, three-dimensional imaging, fused silica, quality control, in situ characterization, situ, evaluation

The project is led by neuroscientist Davi Bock of UVM’s Robert Larner, M.D. College of Medicine, with co-principal investigators Doug Taatjes, director of UVM’s Microscopy Imaging Center, and Mark Ellisman at the University of California San Diego. Together the partners will integrate three complementary capabilities: state-of-the-art high-throughput electron microscopy at the Larner College of Medicine, advanced sample preparation and multimodal imaging expertise at UC San Diego’s National Center for Microscopy and Imaging Research, and large-scale data management at the San Diego Supercomputer Center. The ambition is to design a complete pipeline that carries a preserved biological sample all the way to analyzed, explorable scientific data.

Bock has spent two decades helping to build the science of connectomics, the mapping of nervous systems down to individual neurons and the synapses that link them. His laboratory acquired the electron microscopy images that an international collaboration used to produce the first complete wiring map of an adult fruit fly brain, a landmark achievement published in Nature in 2024. That accomplishment demanded enormous gains in imaging speed and computational power, because the hard problem has never been magnification alone. Electron microscopes already resolve astonishingly small structures; the challenge lies in assembling and aligning millions of images to follow the branching paths of neurons through substantial volumes of tissue, and in converting those image stacks into usable maps.

Having built that capacity, Bock argues the moment has come to widen both its reach and its range. “We built a searchlight to look at one type of problem, and now, with a purpose-built facility for advanced work like this, we will use it to look at many, many different problems,” Bock says. “This new national center will be globally unique in pointing high throughput volume microscopes at the full spectrum of biology. Right now, that doesn’t exist anywhere else.” The observatory’s name is deliberate: just as an astronomical observatory gives many researchers shared access to the heavens, NCUVO will give biologists a shared window onto structures far too small for ordinary light microscopes, the fine details known as ultrastructure that fill the interiors of cells and the spaces between them.

The technical workflow will unfold across three institutions. Tissue preserved in resin will be shaved into thousands of ultrathin slices, each captured at nanometer-scale resolution by a high-throughput electron microscope housed in UVM’s Firestone Medical Research Building. Computers at the San Diego Supercomputer Center will then assemble the slices into coherent three-dimensional volumes. Artificial intelligence will shoulder much of the interpretive burden, identifying cell boundaries, tracing individual neurons through dense tissue, and distinguishing organelles and other features within cells. Researchers will retain tools to verify the automated reconstructions, label structures of interest, and interrogate the data with their own questions. At the San Diego microscopy center, selected regions can be re-imaged at even higher resolution, connecting tiny details to the larger anatomical context mapped in Vermont.

The data volumes will be staggering, measured in petabytes, or millions of gigabytes, per dataset. UVM’s Vermont Advanced Computing Center will support storage and computation, while Ilkay Altintas, chief data science officer at the San Diego Supercomputer Center and principal investigator of the NSF-funded National Data Platform, will guide data curation, drawing on her team’s expertise in organizing, processing and sharing massive scientific datasets and linking the observatory to national cyberinfrastructure. “You can’t just drop a petabyte of data on someone and say mission accomplished,” Bock says. “You have to give them tools to analyze the data.” Ellisman frames the design philosophy the same way: the goal is to transform the latest sample preparation, multimodal imaging and computational technologies into a shared national capability rather than a specialty reserved for a few, empowering scientists to compare many samples at levels of detail ranging from whole tissues down to individual synapses.

Four pilot projects will stress-test the pipeline against different organisms, sample sizes and scientific demands. The first will examine how connections in the mouse hippocampus, a brain region essential for memory, change after learning, in collaboration with Anton Maximov’s laboratory at Scripps Research and Ellisman’s team at UC San Diego; researchers will trace circuits involving neurons flagged as active during a learning task. The second will compare retinal circuitry across species to probe how visual systems adapt to different environments, pairing David Berson’s laboratory at Brown University with Tom Baden’s laboratory at the University of Sussex. Bock points to sharks navigating murky versus clear water as the kind of comparative question these cross-species maps could finally answer. The work will generate datasets large enough, and samples numerous enough, for statistical comparison of how brain structures differ with learning, development or disease.

The third and fourth pilots reach beyond classic neuroscience entirely. Parasitologist Bruno Martorelli Di Genova’s laboratory at UVM will join Christopher Moore’s laboratory at Brown University to study how the parasite Toxoplasma gondii crosses the blood-brain barrier to cause toxoplasmosis, a disease spread through contaminated food and cat litter. “This is an amazing organism because it causes rodents to lose their fear of cat urine,” Bock explains. “It changes the behavior of cat prey to be less frightened of cats. And there’s some evidence that infected humans also are less risk averse.” The fourth pilot will image protists, single-celled organisms with surprisingly elaborate internal architecture, in partnership with Omaya Dudin’s laboratory at the University of Geneva and Gautam Dey’s laboratory at the European Molecular Biology Laboratory in Heidelberg, both recipients of the 2026 EMBO Gold Medal for their work in evolutionary cell biology.

Education is built into the observatory’s mission as well. UVM neuroscience assistant professor Molly Stanley will coordinate a collaboration with Connectomes for Undergraduate Neuroscience Education and Learning, whose leadership includes Andrew Bellemer at Appalachian State University, Kenneth Colodner at Mount Holyoke College and Divya Sitaraman at California State University, East Bay, to develop undergraduate teaching materials from the pilot datasets. The project also plans virtual-reality materials for high school classrooms built on the syGlass platform, along with training opportunities for UVM biomedical engineering master’s students, ensuring that the resource cultivates the next generation of researchers even before the full facility exists.

The five-year effort will deliver a tested design, pilot datasets and an implementation plan for a subsequent national facility, with approximately $15.68 million supporting Bock’s work at UVM and $3.32 million funding UC San Diego’s contributions, including the supercomputer center. The research is fundamentally curiosity-driven basic biology, but the team expects it could illuminate the structural changes that accompany neurodegenerative disease and neural repair, and even inform new approaches to artificial intelligence. “You can’t predict what we’ll find. And that’s the point,” Bock says, invoking Antony van Leeuwenhoek’s first glimpses of microscopic life, observations that seemed abstract at the time but ultimately led to the germ theory of disease. “Anything that you can think of, any tissue, any species, any organism we can look at, we should,” he says. “That’s democratization, broadening the spectrum of questions that can be asked and answered by our national research community.”

Subject of Research: A National Science Foundation-funded connectomics and ultrastructure imaging observatory

Article Title: University of Vermont launches $19 million national research center to unlock secrets of neurobiology

Article References: University of Vermont launches $19 million national research center to unlock secrets of neurobiology. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: connectomics, electron microscopy, neuroscience, National Science Foundation, University of Vermont, three-dimensional imaging, artificial intelligence, ultrastructure, petabyte data, Toxoplasma gondii, brain mapping, scientific observatory

The significance of controlled single-cell rotation extends well beyond a clever laboratory demonstration. When a cell can be turned at will, researchers can perform true three-dimensional imaging with conventional microscopes, capturing morphology and internal architecture from multiple viewing angles. Rotation also matters for mechanobiology, the study of how cells sense and respond to mechanical forces, because orientation relative to a substrate or a neighboring cell influences how forces are transmitted and interpreted. Controlled rotation can further support investigations of cell-cell interactions, intracellular dynamics, and developmental processes in which the spatial arrangement of cellular components is central to function.

Yet programmable rotation has long been an elusive goal. Optical tweezers, magnetic manipulation, electric fields, and acoustic techniques have each made substantial contributions to single-cell control, but most existing approaches depend on specially engineered beam structures, microfabricated mechanical components, or intrinsic asymmetries in the objects being manipulated. Spherical particles and many living cells present a particular difficulty: because they are geometrically symmetric, there is no natural feature that defines a rotation axis. Dynamically switching between different rotation modes within a single platform has remained largely unexplored, which has limited the flexibility of previous systems and confined many of them to narrow, pre-set operating regimes.

The new platform is built on a plasmonic substrate composed of gold nano-islands functionalized with bovine serum albumin, or BSA. When laser light illuminates these nanostructures, they generate localized temperature gradients that drive strong thermo-osmotic flows along the solid-liquid interface. Thermo-osmotic flow is a well-characterized phenomenon in which a temperature gradient at a boundary produces directed fluid motion, and plasmonic substrates are especially effective at creating steep, highly localized gradients because the nanostructures concentrate optical energy into nanoscale volumes. The BSA functionalization plays a complementary role in stabilizing cells at the interface, while polyethylene glycol molecules in the surrounding solution generate depletion forces that gently confine cells near the substrate surface, precisely where the thermo-osmotic flow is strongest.

Control over the flow field comes from a spatial light modulator, a device that can dynamically project programmable laser patterns onto the substrate. By reshaping these patterns in real time, the researchers tailor both the temperature distribution and the resulting flow field, and with them the forces and torques acting on individual cells. This is the conceptual heart of the platform: the rotation axis is not dictated by the geometry of the object but is instead written into the engineered flow field itself. The same cell, sitting in the same spot, can be made to spin in entirely different ways depending only on how the laser light is patterned.

The team first validated the concept using spherical polydimethylsiloxane particles, an ideal test case precisely because a sphere possesses complete geometric symmetry and its rotation axes cannot be defined by shape. Numerical simulations revealed that a single Gaussian laser spot positioned asymmetrically relative to a particle creates a highly non-uniform thermo-osmotic flow field around it. That asymmetry in the flow produces a hydrodynamic torque of sufficient magnitude to drive stable rotation. Crucially, by simply moving the position of the laser spot, the direction of the torque can be tuned continuously, allowing the particle to rotate about different axes. Experimental observations confirmed the theoretical predictions and demonstrated arbitrary-axis rotation of spherical particles, establishing that the axis of rotation is defined entirely by the engineered flow field rather than by particle geometry.

With the principle demonstrated on synthetic spheres, the researchers extended the approach to biological cells, using yeast as a model system. They showed that two distinct rotational modes can be selectively activated through optical pattern engineering. Under a single Gaussian laser spot, the induced thermo-osmotic torque drives the cell to rotate around its major axis, the long axis of the cell body. When the laser pattern is reconfigured into a half-ring shape, an optical torque joins the thermo-osmotic torque, and the combined action reorients the cell and drives continuous rotation around its minor axis. The two modes are therefore not separate operating regimes requiring different hardware; they are two settings of the same optical interface.

Perhaps the most striking capability of the platform is the speed and cleanliness of the switching between these modes. In the reported experiments, the team maintained stable major-axis rotation with a Gaussian beam, then changed the illumination pattern to a half-ring configuration. The cell transitioned into minor-axis rotation in less than one second. The entire process occurred without mechanical movement, sample repositioning, or physical contact, relying solely on optical reconfiguration. For live-cell imaging, this matters enormously: cells are fragile, and any approach that avoids contact, labeling, or chemical modification preserves the native state of the specimen while it is being manipulated.

To understand why the system works so well, the researchers combined multiphysics simulations with electromagnetic calculations. Their analysis showed that major-axis rotation is predominantly driven by thermo-osmotic torque, whereas minor-axis rotation arises from the synergistic coupling of thermo-osmotic and optical torques. Together, these torques create a continuous torque landscape that sustains rotation throughout the entire cycle without trapping the cell in stable equilibrium states. In other words, the optical patterns are designed so that at no point in the rotational cycle does the cell find a configuration where the torques vanish and motion stops; the driving torque persists around the full revolution, which is what enables continuous, stable spinning.

The practical advantages of the platform are considerable. It operates at relatively low optical power, which reduces the risk of photothermal damage to living specimens. It requires no labeling or modification of cells, making it a genuinely label-free technique. It offers exceptional programmability through dynamic optical pattern generation, and unlike many conventional rotational manipulation techniques, it does not depend on complex beam shaping or specialized particle geometries. The researchers believe the technique could become a powerful tool across a broad range of biological and biomedical applications. By integrating with confocal microscopy and other advanced imaging modalities, the platform may enable label-free three-dimensional cellular imaging and reconstruction. It could also facilitate studies of cell mechanics, cellular interactions, developmental biology, and drug screening, where observing a cell from multiple orientations under controlled conditions would add a valuable new dimension to existing assays.

Looking forward, the team envisions combining opto-thermo-osmotic manipulation with emerging metasurface and integrated photonic technologies. Metasurfaces, which are engineered planar optical structures capable of shaping light with subwavelength precision, could replace bulky spatial light modulators with compact, chip-scale pattern generators. Such integration could lead to miniature platforms capable of high-throughput cellular manipulation and analysis, opening new opportunities for next-generation bioanalytical systems in which individual cells are imaged, rotated, and characterized automatically. If that vision is realized, the ability to spin a single cell along any axis with nothing more than a reconfigured beam of light may become as routine a capability in the biology laboratory as focusing the objective lens is today.

Subject of Research: Programmable opto-thermo-osmotic rotation of single cells along arbitrary axes

Article Title: Programmable rotation of single cells along arbitrary axes via opto-thermo-osmotic torque

Article References: Programmable rotation of single cells along arbitrary axes via opto-thermo-osmotic torque. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: cell rotation, opto-thermo-osmotic torque, plasmonic substrate, gold nano-islands, thermo-osmotic flow, spatial light modulator, yeast cells, three-dimensional imaging, mechanobiology, optical manipulation, label-free imaging, Light Science & Applications